Journal articles on the topic 'Copolymers'
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1
Mohammed, Ameen Hadi, Tamador Ali Mahmood, Selvana Adwar Yousif, and Aminu Musa. "Sunflower and Linseed Oils with Decyl Methacrylate Based Copolymers as Green Lubricating Additives." Materials Science Forum 1045 (September 6, 2021): 109–16. http://dx.doi.org/10.4028/www.scientific.net/msf.1045.109.
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During the last few years, the greener additives prepared from bio-raw materials with low-cost and multifunctional applications have attracted considerable attention in the field of lubricant industry. In the present work, copolymers derived from sunflower and linseed oils with decyl methacrylate were synthesized by a thermal method using benzoyl peroxide (BPO) as a radical initiator. Direct polymerization through the double bonds of the fatty acid chain in the presence of a free radical initiator leads to the formation of ecofriendly copolymeric additives (P1 and P2). The copolymers were characterized by Fourier Transform Infrared (FTIR) and Proton Nuclear Magnetic Resonance (1H-NMR). Thermal decomposition of copolymers was determined by thermogravimetric analysis. The average molecular weight was measured by gel permeation chromatography (GPC) method. Different concentrations of prepared copolymer as additives vis 1, 2, 3, and 4 (w/v) were used to examine the rheological behavior and performance evaluation of the formulated base oil. The copolymer acts as an excellent viscosity improver and better pour point depressant.
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Gusarov, M. V., A. V. Krylov, E. A. Deshevaya, and V. A. Tverskoy. "Synthesis and properties of vinyl benzyl alcohol copolymers with styrene." Fine Chemical Technologies 16, no. 5 (November 28, 2021): 399–413. http://dx.doi.org/10.32362/2410-6593-2021-16-5-399-413.
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Objectives. Synthesis and study of the properties of copolymers of vinyl benzyl alcohol (VBA) with styrene with antimicrobial properties.Methods. The study employed infrared (IR) and nuclear magnetic resonance (NMR) spectroscopy, thin-layer chromatography, viscometry, and elemental analysis. The sessile drop method and the pencil method were respectively utilized to determine the contact angles and hardness of the films. The process of testing the film coatings’ resistance to the effects of molds consisted of contaminating the film coatings applied to the glass with mold spores of the All-Russian Collection of Microorganisms in a solution of mineral salts without sugar (Czapek–Dox medium).Results. Homopolymers of vinyl benzyl acetate and its copolymers with styrene were synthesized in this study. Homo- and copolymers of VBA were obtained by saponification. IR and proton NMR (1H NMR) spectroscopy determined the composition of the copolymers. Employing IR spectroscopy, the degree of saponification was monitored by the appearance of the hydroxyl group absorption band and the disappearance of the ester group absorption band. According to the IR spectroscopy data, only an insignificant (~3%) amount of ester groups remains in the saponified copolymers. The influence of the copolymers’ composition on their solubility in various solvents is demonstrated. IR spectroscopy of the copolymers revealed hydrogen-bond formation between the unreacted ester groups and hydroxyl groups formed due to the saponification. The viscometry of the solutions of mixtures of saponified and unsaponified copolymers, solutions of mixtures of saponified copolymer with polyvinyl acetate, and viscometry of saponified copolymers in various solvents all support this conclusion. These bonds’ concentration depends on the copolymer’s composition and can be controlled by the nature of the solvent from which these copolymers’ films are formed. Saponified copolymer solutions form smooth, transparent film coatings with excellent adhesion to metals and silicate glass surfaces. The contact angle of these films, like the hardness, decreases as the VBA units’ concentration in the copolymers increases and depends on the solvent polarity used to form the films. It has been demonstrated that increasing the VBA units concentration suppresses the microorganisms’ growth.Conclusions. Film coatings made of copolymers of styrene with VBA have been shown to have high biocidal activity against molds; can be used to protect structural materials and products from the effects of microorganisms.
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Eliza, Eliza, Desnelli Desnelli, Ady Mara, and Fahma Riyanti. "Study of Effect of Weight Ratio on Copolymerization of Chitosan and Acrylamide." Indonesian Journal of Fundamental and Applied Chemistry 6, no. 3 (October 20, 2020): 96–102. http://dx.doi.org/10.24845/ijfac.v6.i3.96.
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In this research, chitosan copolymer synthesis with acrylamide has been carried out by varying weight of chitosan and acrylamide, namely 2:3, 3:2 and 1:1 using a microwave oven. The copolymers characterization was carried out using FTIR, XRD, SEM and TGA/DTA. The results of the synthesis of chitosan copolymer with acrylamide were obtained the largest percentage of grafting at a ratio of 2:3. From the results of FTIR analysis showed that the copolymer had been successfully synthesized. XRD analysis showed that the copolymers synthesized have amorphous properties compared to chitosan. The results of SEM analysis, the copolymers had a porous structure. Thermal analysis showed that the copolymers have better thermal stability than chitosan. The swelling ability of the CA23 copolymer was higher than that of the CA32 and CA11 copolymers. The chitosan-acrylamide copolymer which was synthesized in a ratio of 2:3 has better properties
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Luo, Song, Xinyu Peng, Ying Chen, Ting Su, Jun Cao, Sai Li, and Bin He. "Synthesis, characterization, and crystallization of biodegradable poly(ε-caprolactone)-poly(L-lactide) diblock copolymers." e-Polymers 15, no. 1 (January 1, 2015): 15–23. http://dx.doi.org/10.1515/epoly-2014-0155.
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AbstractThree diblock copolymers of PCL6k-PLLA2k, PCL6k-PLLA4k, and PCL6k-PLLA6k were prepared and their crystallization behaviors were investigated. The molecular weights of the copolymers calculated from 1H nuclear magnetic resonance spectra were equivalent to the designed molecular weights. The gel permeation chromatography spectra of the copolymers showed one peak, which revealed that the copolymers were monodisperse. The crystallization capability of poly(ε-caprolactone) (PCL) decreased and that of poly(L-lactide) (PLLA) increased when the molecular weight of the PLLA block was increased from 2k to 6k. PCL spherulites in the PCL6k-PLLA2k copolymer film were smaller than those in PCL6k-PLLA4k or PCL6k-PLLA6k copolymer film. PCL spherulites in the PCL6k-PLLA2k copolymer film grew fastest within all three diblock copolymers. An obvious phase separation phenomenon was observed on the surface of PCL6k-PLLA6k copolymer film in atomic force microscopy images.
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Nikolova, Denitsa, Christo Tzachev, Lachezar Christov, and Elena Vassileva. "Poly(Sulfobetaine Methacrylate-co-Vinyl Pyrrolidone) Hydrogels as Potential Contact Lenses Delivery Systems for Timolol Maleate." Gels 9, no. 2 (January 30, 2023): 114. http://dx.doi.org/10.3390/gels9020114.
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The study reveals the development of novel hydrogels based on sulfobetaine methacrylate (SB) and vinyl pyrrolidone (VP) copolymers as potential contact lenses delivery systems of timolol maleate (TM). The novel copolymer networks demonstrated composition dependent swelling kinetics, where the hydrophilicity of VP and the physical network of SB monomeric units play significant roles. TM loading efficiency appeared to slightly depend on the copolymeric composition, increasing upon VP monomeric unit increase. In contrast, the TM release was prolonged when the SB monomeric units content in the copolymers increased, reaching full drug release for 48 h for the SB-rich networks. The transparency of the hydrogels was also studied and the obtained values demonstrate their applicability as potential materials for soft contact lenses. The study has revealed the potential of these novel copolymeric hydrogels as materials for contact lenses delivery systems of timolol maleate.
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Sarikulak, Hikmet Bora, and Songül Şen Gürsoy. "Chemical, Electrochemical and Plasma Polymerization of Pyrrole-Aniline Copolymers and Their Characterization." Asian Journal of Applied Chemistry Research 14, no. 3 (September 21, 2023): 1–9. http://dx.doi.org/10.9734/ajacr/2023/v14i3265.
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Pyrrole-aniline copolymers (poly(Py-co-Ani)) were synthesized using both three chemical, electrochemical and plasma polymerization methods. Comparison of the copolymers synthesized with three methods was investigated. Fourier transform infrared spectroscopy (FT-IR), thermogravymetric analysis (TG-DTA), scanning electron microscopy (SEM) and conductivity results confirmed that the poly(Py-co-Ani) copolymers were successfully obtained in all cases with some differences according to synthesis methods. It was found that plasma method enhanced the thermal stability of the poly(Py-co-Ani) copolymer. The first thermal decomposition temperatures of chemically, electrochemically and plasma polymerized copolymers are 210, 190 and 250 °C, respectively. However, the conductivity value of plasma polymerized copolymer (1,97x10-4 S.cm-1) is lower than that of chemical (4,40x10-4 S.cm-1) and electrochemical (3,14x10-4 S.cm-1) synthesized copolymers. According to findings chemical and electrochemical polymerization methods provides nearly the same properties to the copolymers. Plasma polymerization method provides better thermal properties to copolymer. The both three methods can be used for preparing the pyrrole and aniline copolymers.
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Jeon, Oju, Su Jin Song, Min Hyung Lee, Sang Woo Seo, Cha Yong Choi, and Byoung Soo Kim. "Synthesis and Characterization of Polyethylenimine-Graft-Poly(L-Lactide-Co-Glycolide) Block Copolymers for Gene Delivery." Key Engineering Materials 342-343 (July 2007): 521–24. http://dx.doi.org/10.4028/www.scientific.net/kem.342-343.521.
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Polyethylenimine-graft-poly(L-lactide-co-glycolide) (PEI-g-PLGA) block copolymers were prepared by a ring-opening polymerization of L-lactide and glycolide using PEI as a macroinitiator and stannous octoate as a catalyst in dimethylformamide at 100 °C. The molecular structure of the block copolymers was evaluated with 1H-NMR, and the molecular weight of the block copolymers was determined with gel permeation chromatography. The thermal properties were investigated using differential scanning calorimetery and thermogravimetric analysis. The zetapotential of the pDNA/copolymer complexes was evaluated with dynamic laser light scattering. Cytotoxicity and gene transfection efficiency of PEI-g-PLGA were tested in vitro using human embryonic kidney 293 cell culture. The pDNA/copolymer complexes (N/P = 10) showed a lower zeta-potential than pDNA/PEI25kDa complex, suggesting the lower toxicity of the pDNA/copolymer complexes. The copolymer composition was found to significantly affect the gene transfection efficiency of the pDNA/copolymer complexes. The copolymers with lower contents of PLGA showed higher gene transfection efficiency. These results indicate that these block copolymers are promising candidates for gene delivery vehicles, featuring good biocompatibility, potential biodegradability, and relatively high gene transfection efficiency.
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Szkudlarek, Marian, Elisabeth Heine, Helmut Keul, Uwe Beginn, and Martin Möller. "Synthesis, Characterization, and Antimicrobial Properties of Peptides Mimicking Copolymers of Maleic Anhydride and 4-Methyl-1-pentene." International Journal of Molecular Sciences 19, no. 9 (September 4, 2018): 2617. http://dx.doi.org/10.3390/ijms19092617.
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Synthetic amphiphilic copolymers with strong antimicrobial properties mimicking natural antimicrobial peptides were obtained via synthesis of an alternating copolymer of maleic anhydride and 4-methyl-1-pentene. The obtained copolymer was modified by grafting with 3-(dimethylamino)-1-propylamine (DMAPA) and imidized in a one-pot synthesis. The obtained copolymer was modified further to yield polycationic copolymers by means of quaternization with methyl iodide and dodecyl iodide, as well as by being sequentially quaternized with both of them. The antimicrobial properties of obtained copolymers were tested against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus epidermidis, and Staphylococcus aureus. Both tested quaternized copolymers were more active against the Gram-negative E. coli than against the Gram-positive S. aureus. The copolymer modified with both iodides was best when tested against E. coli and, comparing all three copolymers, also exhibited the best effect against S. aureus. Moreover, it shows (limited) selectivity to differentiate between mammalian cells and bacterial cell walls. Comparing the minimum inhibitory concentration (MIC) of Nisin against the Gram-positive bacteria on the molar basis instead on the weight basis, the difference between the effect of Nisin and the copolymer is significantly lower.
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Zhang, Da Wei, Jin Song Leng, and Yan Ju Liu. "Influence of Radialization Dosage on Shape Memory Effect of Polystyrene Copolymer." Advanced Materials Research 47-50 (June 2008): 690–93. http://dx.doi.org/10.4028/www.scientific.net/amr.47-50.690.
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This paper is concerned about the synthesis of shape memory styrene copolymer and the investigation of the influence of radialization dosage on its shape memory effect. As one of novel actuators in smart materials, shape memory polymers (SMPs) have been investigated intensively. Styrene copolymer with proper cross-linking degree can exhibit shape memory effect (SME). In this paper, the influence of radialization on shape memory effect of styrene copolymer was investigated through altering the dosage of radialization. The radialization dosage of styrene copolymer was determined by changed radicalization time. The glass transition temperature (Tg) of styrene copolymerwas measured by Dynamic Mechanical Analysis (DMA). The shape memory performance of styrene copolymer with different radiated dosage was also evaluated. Results indicated that the shape memory polymer (SMP) was synthesized successfully. The Tg increased from 60°C to 65°C followed by increasing the radialization dosage. Moreover, the SMP experienced good SME and the largest reversible strain of the SMP reached as high as 150%. When heating above Tg+30°C (different copolymers performed different Tg), the shape recovery speed of the copolymers increased with increasing the radialization dosage. However, the recovery speed decreased with increasing the radialization dosage at the same temperature of 95°C.
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Yang, Lei, Cheng Jie Hu, Hai Yang, and Dong Ming Qi. "Synthesis of Polystyrene-b-poly(n-butyl acrylate)-b-Polystyrene Triblock Copolymers as Binder for Pigment Dyeing." Advanced Materials Research 441 (January 2012): 473–77. http://dx.doi.org/10.4028/www.scientific.net/amr.441.473.
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Well-controlled polystyrene-b-poly (n-butyl acrylate)-b-polystyrene (PSt-b-PnBA-b-PSt) triblock copolymers were prepared by RAFT (reversible addition-fragmentation chain transfer) emulsion polymerization process. The mechanical properties of the triblock copolymers were investigated in comparison to the P(nBA-co-St) statistical copolymers. When the PSt content is 20%, the ultimate tensile strength of triblock copolymer is nearly six times the strength of statistical copolymer, while their modulus are all around 3.0×103 Pa. The triblock copolymer films feel smooth and non-tacky as the PSt content is higher than 20%. It indicates that PSt-b-PnBA-b-PSt triblock copolymers can be used as binders in pigment dyeing, providing the dyed fabrics with soft non-tacky handle and good fastness properties.
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Nandekar, Kamlakar. "Novel Applications of Some Organic Copolymers Derived From Phenolic and Nitrogen-Containing Compounds- A Review." Journal of ISAS 2, no. 1 (July 31, 2023): 15–26. http://dx.doi.org/10.59143/isas.jisas.2.1.kdqi5413.
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A variety of organic copolymers have been synthesized from phenolic compounds like p-Hydroxybenzoic acid, p-Hydroxybenzaldehyde, p-Hydroxyacetophenone, and also from nitrogen- containing compound like anthranilic acid, aniline, urea, biurate. These copolymers have been studied for various properties like thermal behavior, kinetic parameters, antimicrobial screening, ion-exchange study, polymer composites, photoluminiscence etc. Kinetic parameters of the copolymers derived from phenolic and nitrogen-containing compounds have been studied using Freeman-Carroll (FC) and Sharp-Wentworth (SW). Based on TGA, thermal stability and decomposition temperature have been studied for the copolymers and composites. Higher thermal stability for copolymer composites has been found as compared to the copolymer because the composite has a high activation energy and more residue left out at the end of the decomposition process. The metal ion uptake capacity of the copolymer have been studied by using the batch equilibrium method and is useful for wastewater treatment. The antimicrobial activity of the copolymers have been studied using the agar diffusion method. Polymer composites have been made from copolymers using an ultra-sonication process and exhibit excellent properties in metal ion uptake for wastewater treatment. The present review paper involves the study of novel applications of the copolymer resins derived from phenolic compound and nitrogen-containing compound.
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Hou, Qiong, Dan Dan Ruan, Lin Tao Hou, and Hong Zhu. "Synthesis and Electroluminescent Properties of Fluorene-Based Three-Component Red Light-Emitting Copolymers." Advanced Materials Research 197-198 (February 2011): 1221–24. http://dx.doi.org/10.4028/www.scientific.net/amr.197-198.1221.
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Novel soluble three-component conjugated copolymers are synthesized by palladium- catalyzed Suzuki coupling reaction from 9,9-dioctylfluorene (DOF), 9-ethylhexylcarbazole (Cz) and 4,7-dithien-2-yl-2,1,3-benzothiadiazole (DBT) with Cz composition varying from 1-15 mol% in the copolymer. All of the polymers are soluble in common organic solvents and are highly photoluminescent. The electrochemical, optical, photoluminescent (PL) and electroluminescent (EL) properties of the copolymers were studied. When the hole transmitting material carbazole is introduced into the copolymer PFO-DBT, the hole mobility of the luminescent layer material is improved. The three-component copolymers compared with copolymer PFO-DBT15, Devices made up of these copolymers still emit saturated red light. The highest external quantum efficiency achieved in the device configuration ITO/PEDT/PFO-Cz-DBT15/Ba/Al is 1.81% for the copolymer for 10% Cz content, higher than that of the device made from PFO-DBT15.
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Wang, Fusong, Lei Zhang, Xiaoshan Zhang, Hechuan Li, and Shaopeng Wu. "Aging Mechanism and Rejuvenating Possibility of SBS Copolymers in Asphalt Binders." Polymers 12, no. 1 (January 4, 2020): 92. http://dx.doi.org/10.3390/polym12010092.
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The styrene–butadiene–styrene (SBS)-modified asphalt pavement has been in growing demand in the road construction field owing to its workable mechanical property and temperature durability. This paper prepared a penetrative rejuvenator (PR) with waste cooking oil (WCO) and emulsified asphalt, then applied PR on SBS copolymers to investigate its aging and rejuvenating effects in an asphalt binder. After a thin film oven test (TFOT) and ultraviolet (UV) aging of SBS copolymers, Fourier transform infrared (FTIR) spectra were used to analyse the aged copolymers’ chemical structure. Moreover, both aged and rejuvenated SBS copolymers were added into a fresh asphalt binder to get two kinds of modified asphalt binders, namely, MAAC (modified by aged copolymer) and MARC (modified by rejuvenated copolymer). Aiming to analyse the monomer effect of SBS copolymers in the asphalt binder, the rheological characteristic with dynamic shear rheometer (DSR), chemical structure with FTIR and physical properties with penetration, soft point and ductility tests were investigated using MAAC and MAAC samples. The results showed that rejuvenated SBS copolymer could improve MAAC’s viscoelasticity, but from FTIR spectral analysis, PR resulted in no chemical changes to SBS copolymers. A tough coat which made MAAC of higher stiffness was observed on the copolymer surface after thermal treatment. UV caused evidently negative effects on SBS copolymer because of accelerating oxidation by ozone, which brought about high possibility of cracks during servicing periods of asphalt pavement. In addition, MAAC was inferior in both rheological and physical properties, which reflected the significance and necessity in consideration of alleviating SBS copolymer aging in field.
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Otero Navas, Ivonne, Milad Kamkar, Mohammad Arjmand, and Uttandaraman Sundararaj. "Morphology Evolution, Molecular Simulation, Electrical Properties, and Rheology of Carbon Nanotube/Polypropylene/Polystyrene Blend Nanocomposites: Effect of Molecular Interaction between Styrene-Butadiene Block Copolymer and Carbon Nanotube." Polymers 13, no. 2 (January 11, 2021): 230. http://dx.doi.org/10.3390/polym13020230.
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This work studied the impact of three types of styrene-butadiene (SB and SBS) block copolymers on the morphology, electrical, and rheological properties of immiscible blends of polypropylene:polystyrene (PP:PS)/multi-walled carbon nanotubes (MWCNT) with a fixed blend ratio of 70:30 vol.%. The addition of block copolymers to PP:PS/MWCNT blend nanocomposites produced a decrease in the droplet size. MWCNTs, known to induce co-continuity in PP:PS blends, did not interfere with the copolymer migration to the interface and, thus, there was morphology refinement upon addition of the copolymers. Interestingly, the addition of the block copolymers decreased the electrical resistivity of the PP:PS/1.0 vol.% MWCNT system by 5 orders of magnitude (i.e., increase in electrical conductivity). This improvement was attributed to PS Droplets-PP-Copolymer-Micelle assemblies, which accumulated MWCNTs, and formed an integrated network for electrical conduction. Molecular simulation and solubility parameters were used to predict the MWCNT localization in the immiscible blend. The simulation results showed that diblock copolymers favorably interact with the nanotubes in comparison to the triblock copolymer, PP, and PS. However, the interaction between the copolymers and PP or PS is stronger than the interaction of the copolymers and MWCNTs. Hence, the addition of copolymer also changed the localization of MWCNT from PS to PS–PP–Micelles–Interface, as observed by TEM images. In addition, in the last step of this work, we investigated the effect of the addition of copolymers on inter- and intra-cycle viscoelastic behavior of the MWCNT incorporated polymer blends. It was found that addition of the copolymers not only affects the linear viscoelasticity (e.g., increase in the value of the storage modulus) but also dramatically impacts the nonlinear viscoelastic behavior under large deformations (e.g., higher distortion of Lissajous–Bowditch plots).]
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Otero Navas, Ivonne Otero, Milad Kamkar, Mohammad Arjmand, and Uttandaraman Sundararaj. "Morphology Evolution, Molecular Simulation, Electrical Properties, and Rheology of Carbon Nanotube/Polypropylene/Polystyrene Blend Nanocomposites: Effect of Molecular Interaction between Styrene-Butadiene Block Copolymer and Carbon Nanotube." Polymers 13, no. 2 (January 11, 2021): 230. http://dx.doi.org/10.3390/polym13020230.
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This work studied the impact of three types of styrene-butadiene (SB and SBS) block copolymers on the morphology, electrical, and rheological properties of immiscible blends of polypropylene:polystyrene (PP:PS)/multi-walled carbon nanotubes (MWCNT) with a fixed blend ratio of 70:30 vol.%. The addition of block copolymers to PP:PS/MWCNT blend nanocomposites produced a decrease in the droplet size. MWCNTs, known to induce co-continuity in PP:PS blends, did not interfere with the copolymer migration to the interface and, thus, there was morphology refinement upon addition of the copolymers. Interestingly, the addition of the block copolymers decreased the electrical resistivity of the PP:PS/1.0 vol.% MWCNT system by 5 orders of magnitude (i.e., increase in electrical conductivity). This improvement was attributed to PS Droplets-PP-Copolymer-Micelle assemblies, which accumulated MWCNTs, and formed an integrated network for electrical conduction. Molecular simulation and solubility parameters were used to predict the MWCNT localization in the immiscible blend. The simulation results showed that diblock copolymers favorably interact with the nanotubes in comparison to the triblock copolymer, PP, and PS. However, the interaction between the copolymers and PP or PS is stronger than the interaction of the copolymers and MWCNTs. Hence, the addition of copolymer also changed the localization of MWCNT from PS to PS–PP–Micelles–Interface, as observed by TEM images. In addition, in the last step of this work, we investigated the effect of the addition of copolymers on inter- and intra-cycle viscoelastic behavior of the MWCNT incorporated polymer blends. It was found that addition of the copolymers not only affects the linear viscoelasticity (e.g., increase in the value of the storage modulus) but also dramatically impacts the nonlinear viscoelastic behavior under large deformations (e.g., higher distortion of Lissajous–Bowditch plots).
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Gao, Man, Chengyuan Shang, Jixian Li, Gang Han, Junkun Tang, Qiaolong Yuan, and Farong Huang. "Synthesis and Characterization of Block Copolymers of Poly(silylene diethynylbenzen) and Poly(silylene dipropargyl aryl ether)." Polymers 13, no. 9 (May 7, 2021): 1511. http://dx.doi.org/10.3390/polym13091511.
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Poly(silylene diethynylbenzene)–b–poly(silylene dipropargyloxy diphenyl propane) copolymer (ABA-A), poly(silylene diethynylbenzene)–b–poly(silylene dipropargyloxy diphenyl ether) copolymer (ABA-O), and a contrast poly(silylene diethynylbenzene) with equivalent polymerization degree were synthesized through Grignard reactions. The structures and properties of the copolymers were investigated via hydrogen nuclear magnetic resonance, Fourier transform infrared spectroscopy, Haake torque rheometer, differential scanning calorimetry, dynamic mechanical analysis, thermogravimetric analysis and mechanical tests. The results show that the block copolymers possess comprehensive properties, especially good processability and good mechanical properties. The processing windows of these copolymers are wider than 58 °C. The flexural strength of the cured ABA-A copolymer reaches as high as 40.2 MPa. The degradation temperatures at 5% weight loss (Td5) of the cured copolymers in nitrogen are all above 560 °C.
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Liu, Dongmei, Kai Gong, Ye Lin, Tao Liu, Yu Liu, and Xiaozheng Duan. "Dissipative Particle Dynamics Study on Interfacial Properties of Symmetric Ternary Polymeric Blends." Polymers 13, no. 9 (May 8, 2021): 1516. http://dx.doi.org/10.3390/polym13091516.
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We investigated the interfacial properties of symmetric ternary An/AmBm/Bn and An/Am/2BmAm/2/Bn polymeric blends by means of dissipative particle dynamics (DPD) simulations. We systematically analyzed the effects of composition, chain length, and concentration of the copolymers on the interfacial tensions, interfacial widths, and the structures of each polymer component in the blends. Our simulations show that: (i) the efficiency of the copolymers in reducing the interfacial tension is highly dependent on their compositions. The triblock copolymers are more effective in reducing the interfacial tension compared to that of the diblock copolymers at the same chain length and concentration; (ii) the interfacial tension of the blends increases with increases in the triblock copolymer chain length, which indicates that the triblock copolymers with a shorter chain length exhibit a better performance as the compatibilizers compared to that of their counterparts with longer chain lengths; and (iii) elevating the triblock copolymer concentration can promote copolymer enrichment at the center of the interface, which enlarges the width of the phase interfaces and reduces the interfacial tension. These findings illustrate the correlations between the efficiency of copolymer compatibilizers and their detailed molecular parameters.
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Golas, Patricia L., Nicolay V. Tsarevsky, Brent S. Sumerlin, Lynn M. Walker, and Krzysztof Matyjaszewski. "Multisegmented Block Copolymers by 'Click' Coupling of Polymers Prepared by ATRP." Australian Journal of Chemistry 60, no. 6 (2007): 400. http://dx.doi.org/10.1071/ch07073.
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Multisegmented block copolymers were prepared by the step-growth click coupling of well-defined block copolymers synthesized by atom transfer radical polymerization (ATRP). α,ω-Diazido-terminated polystyrene-block-poly(ethylene oxide)-block-polystyrene was coupled with propargyl ether in N,N-dimethylformamide in the presence of a CuBr/N,N,N´,N´´,N´´-pentamethyldiethylenetriamine catalyst. The preparation of multisegmented block copolymers was also demonstrated by the click coupling of propargyl ether with another diazido-terminated triblock copolymer, poly(n-butyl acrylate)-block-poly(methyl methacrylate)-block-poly(n-butyl acrylate), and a diazido-terminated pentablock copolymer, polystyrene-block-poly(n-butyl acrylate)-block-poly(methyl methacrylate)-block-poly(n-butyl acrylate)-block-polystyrene. The formation of a product of higher molecular weight and broader molecular weight distribution was verified by triple-detection size exclusion chromatography, which revealed that typically five to seven block copolymers were linked together during the click reaction. Differential scanning calorimetry and dynamic mechanical analysis revealed that the amphiphilic block copolymer behaves as a viscoelastic fluid, while its corresponding multiblock copolymer is an elastic material. The multisegmented block copolymers with partially miscible segments exhibit higher glass transition temperatures than their precursors.
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Uemukai, Toru, Tomoya Hioki, and Manabu Ishifune. "Thermoresponsive and Redox Behaviors of Poly(N-isopropylacrylamide)-Based Block Copolymers Having TEMPO Groups as Their Side Chains." International Journal of Polymer Science 2013 (2013): 1–9. http://dx.doi.org/10.1155/2013/196145.
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Thermoresponsive and redox-active block copolymers having 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) moieties have been synthesized by using the reversible addition-fragmentation chain transfer (RAFT) polymerization technique.N-Isopropylacrylamide (NIPAAm) and 2,2,6,6-tetramethylpiperidyl methacrylate (TEMPMA) monomers were copolymerized stepwise under RAFT polymerization conditions to afford the thermoresponsive block copolymers, PNIPAAm-block-PTEMPMA and PNIPAAm-block-PTEMPMA-block-PNIPAAm. Oxidation of tetramethylpiperidine groups in the copolymers successfully afforded the corresponding TEMPO-containing block copolymers. The resulting triblock copolymer was found to be thermoresponsive showing lower critical solution temperature (LCST) at 34∘C in its aqueous solution. Redox behavior of the resulting copolymer was observed by cyclic voltammetry. The potential of anodic current peak changed below and above the LCST of the block copolymer. These results indicate that the phase transition of thermoresponsive polymer influences the redox potential of TEMPO moieties.
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Lipowska-Kur, Daria, Łukasz Otulakowski, Barbara Trzebicka, Alicja Utrata-Wesołek, and Andrzej Dworak. "Thermoresponsive Nanogels of Modified Poly((di(ethylene glycol) methyl ether methacrylate)-co-(2-aminoethyl methacrylate))s." Polymers 12, no. 8 (July 24, 2020): 1645. http://dx.doi.org/10.3390/polym12081645.
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A series of copolymers of di(ethylene glycol) methyl ether methacrylate (D) and 2-aminoethyl methacrylate (A) (P(D-co-A)) with variable ratios of comonomers were synthesized using atom transfer radical polymerization. Then, the amino groups of obtained copolymers were modified to clickable azide or prop-2-yn-1-yl carbamate groups. A thermoresponsive copolymers were obtained with the value of cloud point temperature (TCP) dependent on the type and number of functional groups in the copolymer and on the concentration of solutions. For P(D-co-A) copolymers, the TCP increased with increasing content of 2-aminoethyl methacrylate comonomer. The presence of azide and prop-2-yn-1-yl carbamate groups caused the changes of TCP of modified copolymers. All studied copolymers in dilute aqueous solutions aggregated above TCP to nanoparticles with sizes dependent on the solution concentration, heating procedures, and types and numbers of functional groups present in a copolymer chain. The presence of hydrophilic elements in the chain and the increase in the copolymer concentration led to the enlargement of the particle sizes. Aggregates were crosslinked using click reaction between an azide and prop-2-yn-1-yl carbamate groups that led to stable thermoresponsive nanogels. A systematic study of the behavior of copolymers allowed the determination of the chains useful for possible application in drug delivery.
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Chen, Jian. "The Irradiation Crosslinking of Poly(vinylidene fluoride-chlorotrifluoroethylene)." Applied Mechanics and Materials 716-717 (December 2014): 7–10. http://dx.doi.org/10.4028/www.scientific.net/amm.716-717.7.
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Vinylidenefluoride (VDF) and chlorotrifluoroethylene (CTFE) copolymers were crosslinked by ultraviolet irradiation, chlorotrifluoroethylene content has a great influence on the crosslinked copolymers, high CTFE content support more joint pots, the properties of the copolymer shows higher storage modulus, the loss modulus gets smaller. The copolymer mechanical properties gets much higher.
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Anbarasan, S., R. Chitra, E. Kayalvizhy, and P. Pazhanisamy. "Synthesis, Characterization and Antimicrobial studies of N-cyclohexyl acrylamide and 7-methacryloyloxy-4-methyl coumarin copolymers." YMER Digital 21, no. 01 (January 19, 2022): 330–38. http://dx.doi.org/10.37896/ymer21.01/31.
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A series of copolymers of N-cyclohexylacrylamide (NCA) and 7-methacryloyloxy-4-methyl coumarin (MACU) were prepared by free radical polymerization using AIBN as initiator in DMF. The copolymer compositions were determined by 1HNMR analysis. The reactivity ratios were determined by linear methods like Finemann-Ross and Kelen-Tudos methods. The value of r1 is less than r 2. So MACU is found to have higher reactivity than NCA. Mean sequence lengths of copolymers were calculated from r1 and r2 values. The product of r1. r2 = 1.1, which is greater than 1 indicates that the copolymers are at random distribution of monomeric unit in the copolymer chain. Thermal studies indicates that the Tg values are higher than the homopolymers of NCA. Antimicrobial studies showed that the copolymers are active against both Bacteria and fungi. However, these copolymers showed excellent antibacterial activity
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Hong, Bo, and Mary A. Fox. "Arene-functionalized polyisocyanides: photophysics of well-defined homopolymers and block copolymers for efficient light harvesting." Canadian Journal of Chemistry 73, no. 11 (November 1, 1995): 2101. http://dx.doi.org/10.1139/v95-259.
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Steady-state and time-resolved fluorescence spectroscopy of the homopolymers and di- and triblock copolymers of 2-naphthylethylisocyanide (7), 9-anthrylethylisocyanide (10), and 2-phenanthrylethylisocyanide (11) exhibit emission from the isolated chromophores, i.e., naphthyl, anthryl, or phenanthryl, upon excitation at 284 or 354 nm. The absence of excimer emission in the fluorescence spectra of all these homopolymers is indicative of a rigid polymeric backbone. Fluorescence quenching in diblock copolymers containing a dimethylaniline donor block and a naphthalene or anthracene acceptor block takes place through directional energy migration to the acceptor–quencher interface. The migrating excited state is then quenched at the interface either by photoinduced electron transfer in the anthracene–dimethylaniline diblock copolymer or by exciplex formation in the naphthalene–dimethylaniline diblock copolymer. Upon incorporation of an intervening block derived from pentamethylphenylethylisocyanide 8, exciplex formation is suppressed in the related triblock copolymer. Transient absorption spectra of this family of di- and triblock copolymers reveal the formation of radical ion pairs, with a lifetime of 1.1 μs in the anthracene–dimethylaniline diblock copolymer. Keywords: electron transfer, energy migration, excimer emission, polyisocyanides, block copolymers.
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Gadzinowski, Mariusz, Maciej Kasprów, Teresa Basinska, Stanislaw Slomkowski, Łukasz Otulakowski, Barbara Trzebicka, and Tomasz Makowski. "Synthesis, Hydrophilicity and Micellization of Coil-Brush Polystyrene-b-(polyglycidol-g-polyglycidol) Copolymer—Comparison with Linear Polystyrene-b-polyglycidol." Polymers 14, no. 2 (January 8, 2022): 253. http://dx.doi.org/10.3390/polym14020253.
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In this paper, an original method of synthesis of Coil-Brush amphiphilic polystyrene-b-(polyglycidol-g-polyglycidol) (PS-b-(PGL-g-PGL)) block copolymers was developed. The hypothesis that their hydrophilicity and micellization can be controlled by polyglycidol blocks architecture was verified. The research enabled comparison of behavior in water of PS-b-PGL copolymers and block–brush copolymers PS-b-(PGL-g-PGL) with similar composition. The Coil-Brush copolymers were composed of PS-b-PGL linear core with average DPn of polystyrene 29 and 13 of polyglycidol blocks. The DPn of polyglycidol side blocks of coil–b–brush copolymers were 2, 7, and 11, respectively. The copolymers were characterized by 1H and 13C NMR, GPC, and FTIR methods. The hydrophilicity of films from the linear and Coil-Brush copolymers was determined by water contact angle measurements in static conditions. The behavior of Coil-Brush copolymers in water and their critical micellization concentration (CMC) were determined by UV-VIS using 1,6-diphenylhexa-1,3,5-trien (DPH) as marker and by DLS. The CMC values for brush copolymers were much higher than for linear species with similar PGL content. The results of the copolymer film wettability and the copolymer self-assembly studies were related to fraction of hydrophilic polyglycidol. The CMC for both types of polymers increased exponentially with increasing content of polyglycidol.
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Gajendiran, M., and S. Balasubramanian. "Biodegradable Amphiphilic Tri-Block Copolymeric Nanoparticles for Controlled MTB Drug Delivery." Advanced Materials Research 584 (October 2012): 460–64. http://dx.doi.org/10.4028/www.scientific.net/amr.584.460.
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. A series of biodegradable amphiphilic tri-block copolymers (PLGA–PEG–PLGA) have been derived from the diblock copolymer poly (lactic–co–glycolic acid (PLGA)) and polyethylene glycol (PEG). The mycobacterium tuberculosis (MTB) drug pyrazinamide (PZA) loaded polymer nanoparticles (NPs) have been prepared by probe-sonication followed by w/o/w double emulsification technique. The copolymers have been characterized by FTIR and 1HNMR spectroscopic techniques, TG-DTA analysis, GPC analysis and powder XRD pattern. The MTB drug loaded polymeric NPs have been characterized by FESEM, powder XRD, HRTEM and XPS analysis. The drug loading efficiency, drug content and in vitro drug release studies have been carried out by spectrophotometry. The drug loading efficiency and drug content of triblock copolymeric NPs were higher than these of diblock copolymeric microparticles (MPs). The in vitro drug release studies indicate that the NPs exhibit initial burst release followed by controlled release of PZA for longer durations. The drug release kinetics mechanism has been evaluated by zero order, first order, Korsemeyer-Peppas (KP) and Higuchi models.
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Tanaka, Yasuyuki, Hisaya Sato, and Junichi Adachi. "Structural Characterization of Diene Block Copolymers by GPC and Ozonolysis—GPC Measurements." Rubber Chemistry and Technology 60, no. 1 (March 1, 1987): 25–34. http://dx.doi.org/10.5254/1.3536119.
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Abstract The sequence distribution and block structure of styrene units in commercial styrene—butadiene and styrene-isoprene copolymers were analyzed by GPC measurements on the original copolymers and on ozonolysis products. Tapered-block structures are clearly differentiated by ozonolysis—GPC measurements. The content of large block styrene sequences in S-B-S type block copolymers was found to be 77 to 99% or more. S-B and S sequences in addition to the S-B-S sequence were observed for most of the triblock copolymers. A star-shaped S-B-S copolymer was distinguished from a linear copolymer by comparison of the molecular weight and chemical composition of the main and shoulder peaks by GPC and also by reference to the molecular weight of the block styrene sequence determined by ozonolysis—GPC measurements. A mixture of block copolymers was estimated for a high-styrene thermoplastic elastomer by GPC and ozonolysis—GPC measurements together with the measurement of chemical composition distribution. In a similar way the block structure was analyzed for S-I-S triblock copolymers.
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Selianitis, Dimitrios, and Stergios Pispas. "Multi-responsive poly(oligo(ethylene glycol)methyl methacrylate)-co-poly(2-(diisopropylamino)ethyl methacrylate) hyperbranched copolymers via reversible addition fragmentation chain transfer polymerization." Polymer Chemistry 12, no. 45 (2021): 6582–93. http://dx.doi.org/10.1039/d1py01320c.
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Multi-responsive P(OEGMA-co-DIPAEMA) hyperbranched copolymers are synthesized via RAFT polymerization. The copolymers form different aggregates in aqueous media depending on solution pH, temperature and copolymer composition.
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Duflot, V. R., A. V. Gaivoronsky, and E. I. Lobanova. "Synthesis of thermosensitive copolymers of N-isopropylacrylamide with 2-aminoethylmethacrylate hydrochloride." Fine Chemical Technologies 16, no. 2 (May 25, 2021): 167–75. http://dx.doi.org/10.32362/2410-6593-2021-16-2-167-175.
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Objectives. Due to the increasing number of oncological diseases, active research into developing new radiopharmaceuticals is underway. Thermosensitive copolymers have valuable physicochemical properties that can be harnessed to develop therapeutic radiopharmaceuticals for treating solid tumors. The aim of this study was to develop a method for producing thermosensitive copolymers that can find use as radionuclide carriers to create therapeutic radiopharmaceuticals for treating solid tumors.Methods. Using radical copolymerization in polar solvents, we synthesized water-soluble copolymers based on N-isopropyl acrylamide and 2-aminoethyl methacrylate hydrochloride. The resulting copolymers were characterized in terms of molecular composition and hydrodynamic properties using gel permeation chromatography, IR spectroscopy, potentiometry, and viscometry. Changes in optical density during temperature scanning helped determine the phase transition temperature (PTT) of aqueous copolymer solutions.Results. We developed a method for preparing copolymers of N-isopropylacrylamide with 2-aminoethyl methacrylate using radical copolymerization in water and isopropanol with a content of 2-aminoethyl methacrylate hydrochloride in a copolymer up to 23 mol %. We studied how the second comonomer affected the PTT of the aqueous copolymer solutions. An increase in the content of 2-aminoethyl methacrylate in the copolymer caused the PTT to increase. We found that the change in the PTT depending on the content of 2-aminoethyl methacrylate units in the copolymer had a straightforward relationship with its content up to 17 mol %. The use of physiological saline as a solvent led to a temperature decrease of the phase transition by two degrees.Conclusions. The method of producing thermosensitive copolymers by radical copolymerization in isopropanol does not allow creating a radionuclide carrier. Solutions of the obtained lowmolecular weight oligomers form coacervate solutions, which will inevitably cause the radionuclide to spread throughout the body. The copolymers obtained by radical copolymerization in water with the content of the second comonomer 2-aminoethyl methacrylate from 10–17 mol % can be used as a radionuclides carrier provided that a physiological solution of sodium chloride is used as a solvent.
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Steinman, Noam Y., Noam Y. Bentolila, and Abraham J. Domb. "Effect of Molecular Weight on Gelling and Viscoelastic Properties of Poly(caprolactone)–b-Poly(ethylene glycol)–b-Poly(caprolactone) (PCL–PEG–PCL) Hydrogels." Polymers 12, no. 10 (October 15, 2020): 2372. http://dx.doi.org/10.3390/polym12102372.
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Hydrogels based on poly(caprolactone)–b-poly(ethylene glycol)–b-poly(caprolactone) (PCL–PEG–PCL) have been evaluated extensively as potential injectable fillers or depots for controlled release of drugs. Common drawbacks of these copolymer systems include instability of aqueous solutions and low mechanical strength of gels, issues which are commonly overcome by adding pendant groups to the end of the copolymer chains. Here, a systematic study of the effects of increasing polymer molecular weight (MW) is presented, utilizing PEG blocks of MW 2, 4 or 8 kDa. Triblock copolymers were prepared by the ring-opening polymerization of Ɛ-caprolactone by PEG. Copolymers prepared with PEG MW 2 kDa did not form hydrogels at any copolymer molecular weight. Copolymers prepared with PEG MW 4 kDa formed gels at MW between 11 and 13.5 kDa, and copolymers prepared with PEG MW 8 kDa formed gels at MW between 16 and 18 kDa. Copolymers with PEG block 8 kDa formed hydrogels with high viscosity (17,000 Pa·s) and mechanical strength (G′ = 14,000 Pa). The increased gel strength afforded by increased molecular weight represents a simple modification of the reactants used in the reaction feed without added synthetic or purification steps. Shear-thinning of PCL-PEG-PCL triblock copolymer hydrogels allowed for injection through a standard 23G syringe, allowing for potential use as dermal fillers or drug delivery depots.
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BAG, DIBYENDU S., SHILPI TIWARI, AKANSHA DIXIT, and KM MEENU. "Chiral Copolymers of (R)-N-(1-Phenyl-Ethyl) Methacrylamide (R-NPEMAM) and 2-Hydroxy Ethyl Methacrylate (HEMA): Investigation of Physico- Chemical Behavior, Thermal Properties and Degradation Kinetics." Journal of Polymer Materials 40, no. 1-2 (August 13, 2023): 105–29. http://dx.doi.org/10.32381/jpm.2023.40.1-2.9.
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In this paper, we report the microstructural investigation and influence of H-bonding on the thermal behavior e.g., glass transition (Tg) and thermal degradation of chiral copolymers of (R)- N-(1-phenyl-ethyl) methacrylamide (R-NPEMAM) and 2-hydroxy ethyl methacrylate (HEMA). The Tg increases with the increase of chiral unit content in the copolymers and then attains optimum at around 25 mole % of chiral content. Thereafter it decreases with the increase of chiral content. The effect of copolymer composition and secondary interaction associated with the Hbonding on the thermal properties of these copolymers was also studied. Secondary interaction, specifically H-bonding has been interpreted using FTIR analysis. The copolymers thermally degrade in three stages. The first and third stages of degradation are associated with the chiral comonomer (R-NPEMAM) whereas the second stage indicates the degradation due to HEMA unit present in the copolymer chain. The activation energies for these degradations of the copolymers have been evaluated using Flynn-Wall and Kissinger method.
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Iftime, Gabriel, Lana Fisher, Almeria Natansohn, and Paul Rochon. "Photoinduced birefringence in copolymers containing Disperse Red 1 and styrene." Canadian Journal of Chemistry 78, no. 4 (April 1, 2000): 409–14. http://dx.doi.org/10.1139/v00-034.
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A series of copolymers of 4'-[[[2-(methacryloyloxy)ethyl]ethyl]amino]-4-nitroazobenzene (DR1M) and an optically "inert" styrene comonomer were tested for photoinduced birefringence. The level of saturated birefringence increased linearly with the content of DR1M in the copolymer. The birefringence per mole of azo chromophore was constant along the copolymer series.Key words: azobenzene, photoinduced birefringence, copolymers, trans-cis isomerization.
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Sun, Dachuan, and Yang Song. "Influences of the Periodicity in Molecular Architecture on the Phase Diagrams and Microphase Transitions of the Janus Double-Brush Copolymer with a Loose Graft." Polymers 14, no. 14 (July 13, 2022): 2847. http://dx.doi.org/10.3390/polym14142847.
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The backbone of the Janus double-brush copolymer may break during long-term service, but whether this breakage affects the self-assembled phase state and microphase transitions of the material is still unknown. For the Janus double-brush copolymers with a periodicity in molecular architecture ranging from 1 to 10, the influences of the architectural periodicity on their phase diagrams and order–disorder transitions (ODT) were investigated by the self-consistent mean field theory (SCFT). In total, nine microphases with long-range order were found. By comparing the phase diagrams between copolymers of different periodicity, a decrease in periodicity or breakage along the copolymer backbone had nearly no influence on the phase diagrams unless the periodicity was too short to be smaller than 3. For copolymers with neutral backbones, a decrease in periodicity or breakage along the copolymer backbone reduced the critical segregation strengths of the whole copolymer at ODT. The equations for the critical segregation strengths at ODT, the architectural periodicity, and the volume fraction of the backbone were established for the Janus double-brush copolymers. The theoretical calculations were consistent with the previous theoretical, experimental, and simulation results.
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Semsarzadeh, Mohammad Ali, Arezoo Sh Dadkhah, and Alireza sabzevari. "High-performance family of polymeric particles prepared from poly(phenylene oxide)-poly(hexyl isocyanate) liquid crystal block copolymer: synthesis and properties study." Polymers and Polymer Composites 30 (January 2022): 096739112211046. http://dx.doi.org/10.1177/09673911221104678.
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The poly (phenylene oxide)-block-poly (hexyl isocyanate) copolymers (PPO-b-PHIC)s were synthesized in various ratios of blocks using the organotitanium coordination method at room temperature. The copolymer particles were prepared by precipitation of concentrated solution of the copolymers in non-solvent under stirring. The synthesized copolymers and their particles were characterized by 1H and 13C nuclear magnetic resonance (1H and 13C NMR), Fourier transform infrared (FTIR) spectra, differential scanning calorimetry (DSC), polarized optical microscope (POM), thermogravimetric analysis (TGA) and scanning electron microscope (SEM). The effect of block ratio on the anisotropic-isotropic transition and liquid crystal texture of copolymers as a function of temperature and concentration of the solution was investigated. The polymeric particles tend to be aligned along the fibrillar direction by increasing the block ratio of amide in the copolymer.
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Alakhras, Fadi. "Electrochemical behavior and conductivity measurements of electropolymerized selenophene-based copolymers." Materials Science-Poland 33, no. 1 (March 1, 2015): 25–35. http://dx.doi.org/10.1515/msp-2015-0007.
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AbstractElectrochemical copolymerization of selenophene and thiophene was performed at a constant electrode potential. The obtained homopolymer films and copolymers were studied and characterized with cyclic voltammetry and conductivity measurements, from which conductivity values around 13.35 S · cm-1 were determined. The influence of the applied electropolymerization potential and the monomer feed ratio of selenophene and thiophene on the copolymers properties was investigated. The obtained copolymers showed good stability of the redox activity in an acetonitrile-based electrolyte solution. At higher polymerization potentials and at higher concentrations of thiophene in the feed, more thiophene units were incorporated into the copolymer chain. The conductivities of the copolymers were between those of homopolymers, implying that oxidation of both monomers was possible and the copolymer chains might accordingly be composed of both selenophene and thiophene units.
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Colvin, Howard, and Charles Bull. "Sulfur/Olefin Copolymers as Vulcanizing Agents for Rubber." Rubber Chemistry and Technology 68, no. 5 (November 1, 1995): 746–56. http://dx.doi.org/10.5254/1.3538771.
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Abstract Sulfur/olefin copolymers are known as vulcanizing agents for rubber, but synthetic procedures for these materials are poor and there is little in the literature to relate the structure of the copolymer with the vulcanizate properties of the rubber. This study discusses a new suspension process for the preparation of sulfur/dicyclopentadiene and sulfur/dicyclopentadiene/styrene copolymers. The relationship between the sulfur/olefin copolymer and vulcanizate properties is discussed in terms of the structure of the copolymer and other reaction products.
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Kotsuchibashi, Y., M. Ebara, A. S. Hoffman, R. Narain, and T. Aoyagi. "Temperature-responsive mixed core nanoparticle properties determined by the composition of statistical and block copolymers in the core." Polymer Chemistry 6, no. 10 (2015): 1693–97. http://dx.doi.org/10.1039/c4py01794c.
Full textAbstract:
Mixed core nanoparticles were prepared from self-assembled statistical and block copolymers by controlling the solution temperature. Interestingly, an equal mass of specific statistical copolymers was successfully loaded into block copolymer micelle cores.
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Kausar, Samia, Alia Erum, Ume Ruqia Tulain, Muhammad Ajaz Hussain, Muhammad Farid-ul-Haq, Nadia Shamshad Malik, and Ayesha Rashid. "Formulation, In Vitro Evaluation, and Toxicity Studies of A. vulgaris-co-AAm Carrier for Vildagliptin." Advances in Polymer Technology 2021 (July 22, 2021): 1–17. http://dx.doi.org/10.1155/2021/6634780.
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This study investigated the use of Artemisia vulgaris L. seed mucilage as a new excipient for sustained delivery of Vildagliptin. Copolymeric carrier of A. vulgaris seed mucilage-co-AAm was devised by using acrylamide (AAm) as a monomer, methylene-bis-acrylamide (MBA) as a crosslinker, and potassium persulfate (KPS) as an initiator through free radical polymerization. Different formulations of A. vulgaris-co-AAm were devised by varying contents of polymer, monomer, crosslinking agent, initiator, and reaction temperature. Copolymeric structures were characterized through XRD analysis, Fourier transform infrared (FTIR) spectroscopy, TGA and DSC analysis, and scanning electron microscopy. Porosity, gel fraction, and Vildagliptin loading capacity of copolymers were also established. Swelling and in vitro drug release studies were conducted. XRD evaluation showed the alteration of the crystalline structure of Vildagliptin into an amorphous form. FTIR analysis confirmed the successful grafting of AAm to A. vulgaris seed mucilage backbone. Porosity was increased with increasing polymer concentration and reaction temperature while it was decreased with an increasing amount of AAm, MBA, and KPS. Gel content was decreased with increasing polymer concentration and reaction temperature while it was increased with an increasing amount of AAm, MBA, and KPS. Acute oral toxicity of copolymeric network was done in animal models to evaluate the safety. Copolymers showed the same swelling behavior at all pH 1.2, 4.5, 6.8, and 7.4. Vildagliptin release from copolymer showed a cumulative trend by increasing polymer content and reaction temperature, while a declining trend was observed with increasing contents of monomer, crosslinking agent, and initiator. Sustained release of Vildagliptin was observed from copolymers and release followed the Korsmeyer-Peppas model. From the acute oral toxicity studies, it is evident that newly synthesized copolymeric carriers are potentially safe for eyes, skin, and vital organs.
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Demina, Tatiana S., Maria G. Drozdova, Chantal Sevrin, Philippe Compère, Tatiana A. Akopova, Elena Markvicheva, and Christian Grandfils. "Biodegradable Cell Microcarriers Based on Chitosan/Polyester Graft-Copolymers." Molecules 25, no. 8 (April 22, 2020): 1949. http://dx.doi.org/10.3390/molecules25081949.
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Self-stabilizing biodegradable microcarriers were produced via an oil/water solvent evaporation technique using amphiphilic chitosan-g-polyester copolymers as a core material in oil phase without the addition of any emulsifier in aqueous phase. The total yield of the copolymer-based microparticles reached up to 79 wt. %, which is comparable to a yield achievable using traditional emulsifiers. The kinetics of microparticle self-stabilization, monitored during their process, were correlated to the migration of hydrophilic copolymer’s moieties to the oil/water interface. With a favorable surface/volume ratio and the presence of bioadhesive natural fragments anchored to their surface, the performance of these novel microcarriers has been highlighted by evaluating cell morphology and proliferation within a week of cell cultivation in vitro.
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Che, Ning, Saina Yang, Hongliang Kang, Ruigang Liu, Zhuang Li, Zhijing Liu, Pingping Li, Xiaozhong Qu, and Yong Huang. "Synthesis and properties of CO2-switchable Dex-g-PAHMA copolymers." Polym. Chem. 5, no. 24 (2014): 7109–20. http://dx.doi.org/10.1039/c4py00987h.
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CO2-switchable Dex-g-PAHMA copolymers were synthesized and characterized. The properties of the graft copolymers and the cytotoxicity and cellular uptake of DOX-loaded Dex-g-PAHMA copolymer micelles were investigated.
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Suzuki, Noriyuki, Daisuke Mizuno, Armando M. Guidote, Shun Koyama, Yoshiro Masuyama, and Masahiro Rikukawa. "Asymmetric Reactions in Water Catalyzed by L-Proline Tethered on Thermoresponsive Ionic Copolymers." Letters in Organic Chemistry 17, no. 9 (September 17, 2020): 717–25. http://dx.doi.org/10.2174/1570178616666190819141307.
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L-Proline was covalently tethered on thermoresponsive ionic block copolymers that formed micelles in aqueous solutions. The block copolymers consisted of a poly(N-isopropylacrylamide) (PNIPAAm) segment and an anionic or cationic polymer segment. These copolymers exhibited lower critical solution temperature (LCST) behavior at ca. 35-40°C, and achieved thermal stimuli-induced formation and dissociation of micelles. The copolymer generated micelles in aqueous solution at a higher temperature, where a catalytic aldol reaction proceeded with high diastereo- and enantioselectivities. The micelles dissociated at lower temperature to form a clear solution such that the products could be efficiently extracted from the aqueous reaction mixture. Extraction of the aldol product with an organic solvent from the aqueous solution of the anionic copolymer was more efficient than from the nonionic copolymer solution.
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Yoon, Seung-Kyun, and Dong-June Chung. "In Vivo Degradation Studies of PGA-PLA Block Copolymer and Their Histochemical Analysis for Spinal-Fixing Application." Polymers 14, no. 16 (August 16, 2022): 3322. http://dx.doi.org/10.3390/polym14163322.
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Polylactic acid (PLA) and polyglycolic acid (PGA) are well-known medical-implant materials. Under the consideration of the limitations of degradable polymeric materials, such as weak mechanical strength and by-product release through the biodegradation process under in vivo environments, PLA–PGA block copolymer is one of the effective alternative implant materials in the clinical field. In our previous study, two types of extremely effective PGA–PLA copolymers (multi/tri-block PGA–PLA copolymers) were synthesized. These synthesized block copolymers could overcome aforementioned issues and also showed good biocompatibility. In this study, the PGA–PLA block copolymers with large molecular weight were synthesized under the same chemical scheme, and their bio durability was confirmed through the in vivo degradation behavior and histochemical analyses (by hematoxylin and eosin and immune staining) in comparison with commercial PLGA random copolymer (medical grade). Specimens for the degradation test were investigated by SEM and X-ray diffractometer (XRD). As a result, the synthesized PGA–PLA block copolymer showed good biocompatibility and had a controlled biodegrading rate, making it suitable for use in resorbable spinal-fixation materials.
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Lazarova, Katerina, Marina Vasileva, Sijka Ivanova, Christo Novakov, Darinka Christova, and Tsvetanka Babeva. "Influence of Macromolecular Architecture on the Optical and Humidity-Sensing Properties of Poly(N,N-Dimethylacrylamide)-Based Block Copolymers." Polymers 10, no. 7 (July 13, 2018): 769. http://dx.doi.org/10.3390/polym10070769.
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The influence of the macromolecular architecture of block copolymers containing poly(N,N-dimethyl acrylamide) (PDMA) on the optical characteristics and sensing properties of corresponding thin films is discussed. Series of hydrophilic PDMA-based copolymers of different chemical composition and chain architecture such as triblock, star-shaped, and branched were synthesized. The copolymers were characterized using conventional spectroscopic techniques as well as methods for characterization of copolymer macromolecular characteristics in solution, namely size-exclusion chromatography and static light scattering. Thin films of the copolymers of nanometer scale thickness were deposited on silicon substrates by the spin-coating method. The refractive index and extinction coefficient of the copolymer films were calculated from the reflectance spectra by using non-linear curve fitting methods and the composition-structure-optical properties relationships were evaluated. Humidity-sensing properties of the films were studied by measuring reflectance spectra of the films at a relative humidity range from 5 to 95%RH. The implementation of the copolymer films as optical sensors of humidity is justified and discussed.
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Yoon, Jongseung, Wonmok Lee, and Edwin L. Thomas. "Self-Assembly of Block Copolymers for Photonic-Bandgap Materials." MRS Bulletin 30, no. 10 (October 2005): 721–26. http://dx.doi.org/10.1557/mrs2005.270.
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AbstractSelf-assembled block copolymer systems with an appropriate molecular weight to produce a length scale that will interact with visible light are an alternative platform material for the fabrication of large-area, well-ordered photonic-bandgap structures at visible and near-IR frequencies.Over the past years, one-, two-, and three-dimensional photonic crystals have been demonstrated with various microdomain structures created through microphase separation of block copolymers. The size and shape of periodic microstructures of block copolymers can be readily tuned by molecular weight, relative composition of the copolymer, and blending with homopolymers or plasticizers.The versatility of photonic crystals based on block copolymers is further increased by incorporating inorganic nanoparticles or liquid-crystalline guest molecules (or using a liquid-crystalline block), or by selective etching of one of the microdomains and backfilling with high-refractive-index materials. This article presents an overview of photonic-bandgap materials enabled by self-assembled block copolymers and discusses the morphology and photonic properties of block-copolymer-based photonic crystals containing nanocomposite additives.We also provide a view of the direction of future research, especially toward novel photonic devices.
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Mu, Mingwei, Tomohiro Konno, and Kazuhiko Ishihara. "Spontaneous Hydrogel Formation Through Hydrophobic Interactions in an ABA-type Block Copolymer Composed of Poly(2-methacryloyloxyethyl phosphorylcholine) and Poly(n-butyl methacrylate) Segments." MRS Advances 3, no. 30 (2018): 1691–96. http://dx.doi.org/10.1557/adv.2018.58.
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ABSTRACTIn this study, the spontaneous formation of hydrogels from a water-soluble and amphiphilic ABA-type block copolymer in an aqueous system was examined. The block copolymers were composed of poly(2-methacryloyloxyethyl phosphorylcholine) (MPC) as the B segment and poly(n-butyl methacrylate) (BMA) as the A segment. A two-step living radical polymerization of the corresponding monomers yielded a well-defined ABA-type block copolymer. By regulating the polymerization degree of each segment, the water solubility and amphiphilic natures of the resulting block copolymer could be controlled. The block copolymers spontaneously formed hydrogels when the composition of water in the medium increased to 80 vol% in the water/ethanol mixture. This was due to molecular aggregation of the block copolymers driven by the hydrophobic interactions between the poly(BMA) segments in the polymer. This hydrogel formation depended on the composition and polymerization degree of the MPC units. The poly(MPC) also showed good biocompatibility, thereby rendering the block copolymers applicable for the immobilization of biological components such as antibodies and enzymes and the encapsulation of cells under mild conditions.
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Wei, Chew Kang, Nor Azura Abdul Rahim, and Michiya Fujiki. "Removal of “Majority-Rule” and “Sergeant-Soldier” Polysilane Scaffold from the Hetero-Aggregation System Consisting Circularly Polarized Polydioctylfluorene." Materials Science Forum 1075 (November 30, 2022): 71–77. http://dx.doi.org/10.4028/p-ve3pi0.
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The “majority-rule” and “sergeant-soldier” principle action containing either or both non-charged chiral helix of both Poly (n-hexyl-(S)-2-methylbutylsilane) (PSi-S) and poly (n-hexyl-(R)-2-methylbutylsilane) (PSi-R) were employed as scaffold to determine the polymer capability to amplified chiral shape to the achiral poly (9,9-di-n-octylfluorene) PF8 in a hetero-aggregate system. The majority-rule polysilane refers to the PSi-R-ran-PSi-S copolymers with excess copolymers of R or S in a copolymer system. Meanwhile, the “sergeant and soldier” polysilane was described as PSi-R(S)-ran-PSi-iBu copolymers when one chiral element imposes its screw sense on a large “platoon” of achiral copolymer fragments. For PSi-R-ran-PSi-S copolymers, the effect is rather small featuring PF8 small monotonic increase along with the percentage of back-bone chiral unit. In PSi-R(S)-ran-PSi-iBu copolymer systems, the helix inversion is more obvious in which the PF8 followed the PSi chiral screw preferences.
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He, Tingyu, Yanqiu Wang, Atsushi Narumi, Liang Xu, Shin-ichiro Sato, Xiande Shen, and Toyoji Kakuchi. "Precise Synthesis and Thermoresponsive Property of Poly(ethyl glycidyl ether) and Its Block and Statistic Copolymers with Poly(glycidol)." Polymers 13, no. 22 (November 9, 2021): 3873. http://dx.doi.org/10.3390/polym13223873.
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In this paper, we describe a comprehensive study of the thermoresponsive properties of statistic copolymers and multiblock copolymers synthesized by poly(glycidol)s (PG) and poly(ethyl glycidyl ether) (PEGE) with different copolymerization methods. These copolymers were first synthesized by ring-opening polymerization (ROP), which was initiated by tert-butylbenzyl alcohol (tBBA) and 1-tert-butyl-4,4,4-tris(dimethylamino)-2,2-bis[tris(dimethylamino)phosphoranylidenamino]-2Λ5,4Λ5-catenadi(phosphazene) (t-Bu-P4) as the catalyst, and then the inherent protective groups were removed to obtain the copolymers without any specific chain end groups. The thermoresponsive property of the statistic copolymer PGx-stat-PEGEy was compared with the diblock copolymer PGx-b-PEGEy, and the triblock copolymers were compared with the pentablock copolymers. Among them, PG-stat-PEGE, PG-b-PEGE-b-PG-b-PEGE-b-PG, and PEGE-b-PG-b-PEGE-b-PG-b-PEGE, and even the specific ratio of PEGE-b-PG-b-PEGE, exhibited LCST-type phase transitions in water, which were characterized by cloud point (Tcp). Although the ratio of x to y affected the value of the Tcp of PGx-stat-PEGEy, we found that the disorder of the copolymer has a decisive effect on the phase-transition behavior. The phase-transition behaviors of PG-b-PEGE, part of PEGE-b-PG-b-PEGE, and PG-b-PEGE-b-PG copolymers in water present a two-stage phase transition, that is, firstly LCST-type and then the upper critical solution temperature (UCST)-like phase transition. In addition, we have extended the research on the thermoresponsive properties of EGE homopolymers without specific α-chain ends.
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Liu, Dongmei, Huifeng Bo, Yongchao Jin, Deyang Li, Zhanxin Zhang, Kai Gong, Ye Lin, and Sijia Li. "Effects of concentration and chain length of the sequence copolymer on interfacial properties of homopolymers/sequence copolymers ternary blends: A DPD simulation study." PLOS ONE 17, no. 7 (July 26, 2022): e0270094. http://dx.doi.org/10.1371/journal.pone.0270094.
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The effect of the concentration and chain length of the copolymer AB with sequence length τ = 8 on the interfacial properties of the ternary mixtures A10/AB/B10 are investigated by the dissipative particle dynamics (DPD) simulations. It is found that: i) As the copolymer concentration varies from 0.05 to 0.15, increasing the copolymer enrichment at the center of the interface enlarges the interface width ω and reduces the interfacial tension. However, as the concentration of the sequence copolymers further increases to 0.2, because the interface has formed micelles and the micellization could lower the efficiency of copolymers as a compatibilizer, the interfacial tension exhibits a slightly increase; ii) elevating the copolymer chain length, the copolymer volumes vary from a cylinder shape to a pancake shape. The blends of the copolymer with chain length Ncp = 24 exhibit a wider interfacial width w and a lower interfacial tension γ, which indicates that the sequenced copolymer Ncp = 24 exhibits a better performance as the compatibilizers. This study illustrates the correlations between the reduction in interfacial tension produced by the sequence copolymers and their molecular parameters, which guide a rational design of an efficient compatibilizer.
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Kaliva, Maria, Anthie Georgopoulou, Dimitrios A. Dragatogiannis, Costas A. Charitidis, Maria Chatzinikolaidou, and Maria Vamvakaki. "Biodegradable Chitosan-graft-Poly(l-lactide) Copolymers For Bone Tissue Engineering." Polymers 12, no. 2 (February 4, 2020): 316. http://dx.doi.org/10.3390/polym12020316.
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The design and synthesis of new biomaterials with adjustable physicochemical and biological properties for tissue engineering applications have attracted great interest. In this work, chitosan-graft-poly(l-lactide) (CS-g-PLLA) copolymers were prepared by chemically binding poly(l-lactide) (PLLA) chains along chitosan (CS) via the “grafting to” approach to obtain hybrid biomaterials that present enhanced mechanical stability, due to the presence of PLLA, and high bioactivity, conferred by CS. Two graft copolymers were prepared, CS-g-PLLA(80/20) and CS-g-PLLA(50/50), containing 82 wt % and 55 wt % CS, respectively. Degradation studies of compressed discs of the copolymers showed that the degradation rate increased with the CS content of the copolymer. Nanomechanical studies in the dry state indicated that the copolymer with the higher CS content had larger Young modulus, reduced modulus and hardness values, whereas the moduli and hardness decreased rapidly following immersion of the copolymer discs in alpha-MEM cell culture medium for 24 h. Finally, the bioactivity of the hybrid copolymers was evaluated in the adhesion and growth of MC3T3-E1 pre-osteoblastic cells. In vitro studies showed that MC3T3-E1 cells exhibited strong adhesion on both CS-g-PLLA graft copolymer films from the first day in cell culture, whereas the copolymer with the higher PLLA content, CS-g-PLLA(50/50), supported higher cell growth.
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Jamshidi, H., and A. Rabiee. "Synthesis and Characterization of Acrylamide-Based Anionic Copolymer and Investigation of Solution Properties." Advances in Materials Science and Engineering 2014 (2014): 1–6. http://dx.doi.org/10.1155/2014/728675.
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The copolymer of acrylamide (AM) and 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS) was synthesized through radical solution polymerization by potassium persulfate as initiator. By changing the AMPS feed ratio from 10 to 70%, and keeping other reaction conditions constant, different copolymers were synthesized. The techniques of Fourier transform infrared (FTIR) and nuclear magnetic resonance (1H-13C-NMR) spectroscopy were used for identification of functional groups and confirmation of copolymers’ structure. Intrinsic and apparent viscosity of samples were measured in aqueous sodium chloride solution under standard conditions. The anionic degree of copolymers was determined by back titration method and by13C-NMR spectroscopy. Molecular weight of copolymers was determined by the Mark-Houwink relationship. The measured molecular weight of samples showed that we have acquired a high molecular weight product. The effect of different range of shear rates on solution viscosity was evaluated. The copolymer solutions showed non-Newtonian shear thinning behavior. The performance of copolymers with respect to shear resistance and molecular weight was evaluated from industry application standpoint.
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Pavlopoulou, Eleni, Kiriaki Chrissopoulou, Stergios Pispas, Nikos Hadjichristidis, and Spiros H. Anastasiadis. "The Micellization of Well-Defined Single Graft Copolymers in Block Copolymer/Homopolymer Blends." Polymers 13, no. 5 (March 9, 2021): 833. http://dx.doi.org/10.3390/polym13050833.
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A series of well-defined (polyisoprene)2(polystyrene), I2S, single graft copolymers with similar total molecular weights but different compositions, fPS, were blended with a low molecular weight polyisoprene homopolymer matrix at a constant concentration 2 wt%, and the micellar characteristics were studied by small-angle x-ray scattering. To investigate the effect of macromolecular architecture on the formation and characteristics of micelles, the results on the single graft copolymers were compared with those of the corresponding linear polystyrene-b-polyisoprene diblock copolymers, SI. The comparison reveals that the polystyrene core chains are more stretched in the case of graft copolymer micelles. Stretching turned out to be purely a result of the architecture due to the second polyisoprene block in the corona. The micellization of a (polystyrene)2(polyisoprene), S2I, graft copolymer was also studied, and the comparison with the results of the corresponding I2S and SI copolymers emphasizes the need for a critical core volume rather than a critical length of the core-forming block, in order to have stable micelles. Finally, the absence of micellization in the case of the I2S copolymer with the highest polystyrene volume fraction is discussed. For this sample, macrophase separation occurs, with polyisoprene cylinders formed in the copolymer-rich domains of the phase-separated blends.