Artigos de revistas: "Polymer chain conformation"

1

Qin, Linlin, Linling Li, Ye Sha, Ziyu Wang, Dongshan Zhou, Wei Chen e Gi Xue. "Conformational Transitions of Polymer Chains in Solutions Characterized by Fluorescence Resonance Energy Transfer". Polymers 10, n.º 9 (10 de setembro de 2018): 1007. http://dx.doi.org/10.3390/polym10091007.

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The critical overlap concentration C* is an important concept in polymer solutions and is defined as the boundary between dilute and semidilute regimes. In this study, the chain conformational changes of polystyrene (PS) with both high (Mn = 200,000 Da) and low (Mn = 13,000 Da) molecular weights in cis-decalin were compared by intrachain fluorescence resonance energy transfer (FRET). The random labeling of donor and acceptor chromophores strategy was employed for long PS chains, whereas chain-end labeling was used for short PS chains. By monitoring the spectroscopic intensity ratio between acceptor and donor, the concentration dependence on chain conformation from dilute to semidilute solutions was determined. Both long and short chains exhibit a conformational transition concentration, above which the polymer chains begin to collapse with concentration significantly. Interestingly, for randomly labeled polymer long chains, such concentration is consistent with C* determined from the viscosity result, below which only slight conformational change of polymer chain takes place. However, for the chain-end labeled short chain, the conformational transition concentration takes place earlier than C*, below which no significant polymer conformation change is observed.

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Qiu, Xing, Cunliang Hu, Jingqing Li, Dinghai Huang e Shichun Jiang. "Role of conformation in crystal formation and transition of polybutene-1". CrystEngComm 21, n.º 29 (2019): 4243–49. http://dx.doi.org/10.1039/c9ce00576e.

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Polymer conformation is the molecular basis underlying essentially all physical properties of polymers, and chain conformation and conformational energy play central roles in crystalline structure formations and structure transitions of polymers.

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Kugimoto, Daisuke, Aoi Taniguchi, Masaki Kinoshita e Isamu Akiba. "Effect of Molecular Architecture on Associating Behavior of Star-Like Amphiphilic Polymers Consisting of Plural Poly(ethylene oxide) and One Alkyl Chain". Polymers 13, n.º 3 (31 de janeiro de 2021): 460. http://dx.doi.org/10.3390/polym13030460.

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Associating behavior of star-like amphiphilic polymers consisting of two or three poly(ethylene oxide) (PEO) chains and one stearyl chain (C18) was investigated. Although the aggregation number (Nagg) of linear analogue of amphiphilic polymers monotonically decreased with increasing number-average molecular weight of PEO (Mn,PEO), the Nagg of micelles of star-like amphiphilic polymers with Mn,PEO = 550 g/mol was smaller than that with Mn,PEO = 750 g/mol, whereas that with Mn,PEO ≥ 750 g/mol showed general Mn,PEO dependence. Small-angle X-ray scattering analyses revealed that the occupied area of one PEO chain on the interface between hydrophobic core and corona layer in the micelles of star-like polymers was much narrower than that in the linear amphiphilic polymers. This result indica ted the PEO chains of star-like polymers partially took unfavorable conformation near the core–corona interface in polymer micelles. The effect of local conformation of PEO chains near the interface on the associating behavior became significant as Mn,PEO decreased. Therefore, in polymer micelles of star-like amphiphilic polymers containing PEO with Mn,PEO = 550 g/mol, the enlargement of occupied area of PEO on the core–corona interface should be caused to avoid the formation of unfavorable conformations of partial PEO chains, resulting in a decrease in Naggs.

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Guo, Yingying, e Linqing Bai. "Dissipative Particle Dynamics Simulation for the Self-Assembly of Symmetric Pentablock Terpolymers Melts under 1D Confinements". Polymers 15, n.º 19 (3 de outubro de 2023): 3982. http://dx.doi.org/10.3390/polym15193982.

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The phase behavior of CBABC pentablock terpolymers confined in thin films is investigated using the Dissipative Particle Dynamic method. Phase diagrams are constructed and used to reveal how chain length (i-block length), block composition and wall selectivity influence the self-assembly structures. Under neutral walls, four categories of morphologies, i.e., perpendicular lamellae, core–shell types of microstructures, complex networks, and half-domain morphologies, are identified with the change in i-block length. Ordered structures are more common at weak polymer–polymer interaction strengths. For polymers of a consistent chain length, when one of the three components has a relatively smaller length, the morphologies transition is sensitive to block composition. With selective walls, parallel lamellae structures are prevalent. Wall selectivity also impacts chain conformations. While a large portion of chains form loop conformations under A-selective walls, more chains adopt bridge conformation when the wall prefers C-blocks. These findings offer insights for designing nanopatterns using symmetric pentablock terpolymers.

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Hu, Zhongjian, Ryan T. Haws, Zhuping Fei, Pierre Boufflet, Martin Heeney, Peter J. Rossky e David A. Vanden Bout. "Impact of backbone fluorination on nanoscale morphology and excitonic coupling in polythiophenes". Proceedings of the National Academy of Sciences 114, n.º 20 (2 de maio de 2017): 5113–18. http://dx.doi.org/10.1073/pnas.1620722114.

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Fluorination represents an important strategy in developing high-performance conjugated polymers for photovoltaic applications. Here, we use regioregular poly(3-ethylhexylthiophene) (P3EHT) and poly(3-ethylhexyl-4-fluorothiophene) (F-P3EHT) as simplified model materials, using single-molecule/aggregate spectroscopy and molecular dynamic simulations, to elucidate the impacts of backbone fluorination on morphology and excitonic coupling on the molecular scale. Despite its high regioregularity, regioregular P3EHT exhibits a rather broad distribution in polymer chain conformation due to the strong steric hindrance of bulky ethylhexyl side chains. This conformational variability results in disordered interchain morphology even between a few chains, prohibiting long-range effective interchain coupling. In stark contrast, the experimental and molecular dynamic calculations reveal that backbone fluorination of F-P3EHT leads to an extended rod-like single-chain conformation and hence highly ordered interchain packing in aggregates. Surprisingly, the ordered and close interchain packing in F-P3EHT does not lead to strong excitonic coupling between the chains but rather to dominant intrachain excitonic coupling that greatly reduces the molecular energetic heterogeneity.

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Sikorski, Andrzej. "Diffusion of Confined Polymer Chains". Defect and Diffusion Forum 237-240 (abril de 2005): 169–74. http://dx.doi.org/10.4028/www.scientific.net/ddf.237-240.169.

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Simple lattice model of polymer systems was developed and studied using the Monte Carlo method. The model chains were star-branched with f = 3 arms and rings. The number of polymer segments in a chain was varied up to 800. The chains were built on a simple cubic lattice with the excluded volume interactions only (the athermal system). The polymers were confined between two parallel impenetrable walls with a set of irregular obstacles what can be treated as porous media. A Metropolis-like sampling algorithm employing local changes of chain conformation was used. The dynamic properties of the model system were studied. The differences in the mobility of chains with different internal architectures were shown and discussed. The possible mechanisms of motions were presented.

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Kobayashi, Masamichi, e Takehito Kozasa. "Conformational Ordering Process on Physical Gelation of Syndiotactic Polystyrene/Solvent Systems Revealed by Time-Resolved Infrared Spectroscopy". Applied Spectroscopy 47, n.º 9 (setembro de 1993): 1417–24. http://dx.doi.org/10.1366/0003702934067450.

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Syndiotactic polystyrene (SPS) dissolved in various organic solvents forms stable gels. Infrared spectroscopic research shows that SPS molecules assume highly ordered TTGG conformation in gels, giving rise to many infrared bands characteristic of the regular TTGG sequences. The behavior of the conformational ordering is strongly dependent on the solvent and the temperature. The time evolution of the conformational order on gelation has been investigated for SPS/CHCl3 systems at various polymer concentrations and temperatures by time-resolved infrared spectroscopy. By the analysis of the rate of formation of the ordered conformation derived from the time-resolved intensity measurement of the conformation-sensitive band at 572 cm−1, the number of the chain segments that contribute to the formation of clusters having ordered TTGG conformation has been evaluated as a function of temperature. The results indicate that at a temperature around 10°C the conformation ordering proceeds through clustering of five chain segments. The number decreases with lowering temperature and becomes unity below a certain temperature, suggesting that the ordering proceeds via self-organization within one chain. Such a crossover between the two mechanisms is found for other solvents, although the crossover temperature depends on the solvent. It has been concluded that strong interactions between polymer and solvent molecules play important roles in controlling the gelation behavior of SPS/solvent systems.

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Tanaka, Fumihiko, e Hideharu Ushiki. "Chain conformation in ternary polymer solutions". Macromolecules 21, n.º 4 (julho de 1988): 1041–46. http://dx.doi.org/10.1021/ma00182a033.

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Jones, Ronald L., Sanat K. Kumar, Derek L. Ho, Robert M. Briber e Thomas P. Russell. "Chain conformation in ultrathin polymer films". Nature 400, n.º 6740 (julho de 1999): 146–49. http://dx.doi.org/10.1038/22080.

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10

Cotton, J. P. "Conformation of a polymer chain in liquid crystalline polymers". Neutron News 1, n.º 3 (janeiro de 1990): 22–23. http://dx.doi.org/10.1080/10448639008202040.

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11

Zulkifli, Ahmad. "Crystal Structure of Aromatic Polysulfones Containing Biphenylene Units". Advanced Materials Research 287-290 (julho de 2011): 1548–52. http://dx.doi.org/10.4028/www.scientific.net/amr.287-290.1548.

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Crystal structure of an aromatic polysulfones containing biphenylene units was elucidated using diffraction simulation technique extracted from X-ray data and interfaced with computational modeling. The chain conformations and configurations were derived from a synthesized oligomer and several analogous structure of past studies. It was found that the polymer adopt an orthorhombicCmcmwith the adjacent aromatic rings attached to the sulfone linkage orthogonal to each other whilst the biphenylene unit are coplanar. The chain conformation and crystal systems are consistent with the analogous polymer containing wholly uniphenylene unit.

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12

Lu, Dan, Aihua Chai, Xiuxia Hu, Peihua Zhong, Nianqian Kang, Xianfei Kuang e Zhiyong Yang. "Conformational Transition of Semiflexible Ring Polyelectrolyte in Tetravalent Salt Solutions: A Simple Numerical Modeling without the Effect of Twisting". International Journal of Molecular Sciences 25, n.º 15 (29 de julho de 2024): 8268. http://dx.doi.org/10.3390/ijms25158268.

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In this work, the conformational behaviors of ring polyelectrolyte in tetravalent salt solutions are discussed in detail through molecular dynamics simulation. For simplification, here we have neglected the effect of the twisting interaction, although it has been well known that both bending and twisting interactions play a deterministic in the steric conformation of a semiflexible ring polymer. The salt concentration CS and the bending energy b take a decisive role in the conformation of the ring polyelectrolyte (PE). Throughout our calculations, the b varies from b = 0 (freely joint chain) to b = 120. The salt concentration CS changes in the range of 3.56 × 10−4 M ≤ CS ≤ 2.49 × 10−1 M. Upon the addition of salt, ring PE contracts at first, subsequently re-expands. More abundant conformations are observed for a semiflexible ring PE. For b = 10, the conformation of semiflexible ring PE shifts from the loop to two-racquet-head spindle, then it condenses into toroid, finally arranges into coil with the increase of CS. As b increases further, four phase transitions are observed. The latter two phase transitions are different. The semiflexible ring PE experiences transformation from toroid to two racquet head spindle, finally to loop in the latter two phase transitions. Its conformation is determined by the competition among the bending energy, cation-bridge, and entropy. Combined, our findings indicate that the conformations of semiflexible ring PE can be controlled by changing the salt concentration and chain stiffness.

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Kochervinskii, V. V., A. Pavlov, N. Kozlova, N. Shmakova, D. A. Kiselev e M. D. Malinkovich. "Influence of Metastable States on Electrophysical Properties in Ferroelectric Crystalline Polymers". Key Engineering Materials 605 (abril de 2014): 499–502. http://dx.doi.org/10.4028/www.scientific.net/kem.605.499.

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The poling and local piezoresponse mechanism has been investigated in ferroelectric polymers. Isotropic 94/6 composition vinylidenefluoride and tetraflouroethylene copolymer films is formed from acetone at room temperature by slow evaporation of solvent. The copolymer crystallization results in metastability (nonequilibre) form at high overcooling temperatures. IR spectroscopy shows occurrence of isomers with conformation TGTG-, T3GT3G-and (TT)n. The local piezoresponse shows that ferroelectric domains include crystals areas as well as nonordered phase. After annealing by heating to 150 oC was found conformation changes in polymer chain: T3GT3G-TGTG-and T3GT3G-(TT)n. It is show that the regular conformation chains length rising after annealing. Polarization value decreasing kinetic was investigated by piezoresponse force microscopy method.

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Park, Juhae, Sung-Gyu Lee, Yannick Vesters, Joren Severi, Myungwoong Kim, Danilo De Simone, Hye-Keun Oh e Su-Mi Hur. "Molecular Modeling of EUV Photoresist Revealing the Effect of Chain Conformation on Line-Edge Roughness Formation". Polymers 11, n.º 12 (22 de novembro de 2019): 1923. http://dx.doi.org/10.3390/polym11121923.

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Extreme ultraviolet lithography (EUVL) is a leading-edge technology for pattern miniaturization and the production of advanced electronic devices. One of the current critical challenges for further scaling down the technology is reducing the line-edge roughness (LER) of the final patterns while simultaneously maintaining high resolution and sensitivity. As the target sizes of features and LER become closer to the polymer size, polymer chain conformations and their distribution should be considered to understand the primary sources of LER. Here, we proposed a new approach of EUV photoresist modeling with an explicit description of polymer chains using a coarse-grained model. Our new simulation model demonstrated that interface variation represented by width and fluctuation at the edge of the pattern could be caused by characteristic changes of the resist material during the lithography processes. We determined the effect of polymer chain conformation on LER formation and how it finally contributed to LER formation with various resist material parameters (e.g., Flory–Huggins parameter, molecular weight, protected site ratio, and Tg).

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15

MU, DAN, JIAN-QUAN LI, SONG WANG e JIAN-FENG WANG. "MOLECULAR DYNAMICS SIMULATION OF THE ADSORPTION AND DIFFUSION OF A SINGLE POLYDIMETHYLSILOXANE POLYMER CHAIN ON A SILICON (111) SURFACE". Journal of Theoretical and Computational Chemistry 11, n.º 04 (16 de julho de 2012): 697–708. http://dx.doi.org/10.1142/s0219633612500460.

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The adsorption of polydimethylsiloxane (PDMS) single chain with different chain lengths on a silicon (111) surface were studied by molecular dynamics simulations. The relative dielectric constant was selected to be 1 and 78.0 to mimic in vacuum and in solution environment, respectively. The chains were all present as two-dimensional (2D) adsorption conformation on the surface but different conformations and dynamic properties were found in the two absolutely different environments. The relationship between the adsorption energy of the different chain lengths and the degree of polymerization follows a linear function and the average adsorption energy per segment is -0.42 kcal/mol. In addition, the diffusion coefficient (D) of such chains scales with the degree of polymerization (N) as N-3/2.

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Ostolska, Iwona, e Małgorzata Wiśniewska. "Influence of Selected Factors on the Adsorption Layer Structure of Polyamino Acids and Their Block Copolymers at the Solid–Aqueous Solution Interface". Molecules 28, n.º 24 (14 de dezembro de 2023): 8080. http://dx.doi.org/10.3390/molecules28248080.

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The adsorption mechanism of different polymers containing ionic polyamino acids monomers in the chain structure at the solid–liquid interface was investigated. Initially, the influence of molecular weight and solution pH on simple polyamino acids (poly(L-aspartic acid) and poly(L-lysine) binding was determined. Considering the obtained dependencies, the polymer adsorption layer conformation was proposed in the systems containing block copolymers (both diblock and symmetrical triblock) consisting of polypeptide as well as poly(ethylene glycol) fragments. The presented studies focused on the application of two experimental methods. The polymer adsorption was carried out using the batch method and the adsorbate concentration was determined spectrophotometrically. Then, the turbidimetric measurements were taken. The analysis of the obtained results showed that the adsorption process of block copolymers depends on two factors. Firstly, the solution pH determines both the nature of the interactions of the copolymer structural units with the solid surface and the conformation of the polypeptide chains. The second parameter influencing the adsorption layer structure is the ratio of the lengths of both blocks. Introducing a short PEG fragment into the polymer main chain may improve the polymer adsorption properties by increasing the number of interactions with the adsorbent surface.

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Chen, Hao, Xuhong Chen, Huiying Chen, Xin Liu, Junxing Li, Jun Luo, Aihua He, Charles C. Han, Ying Liu e Shanshan Xu. "Molecular Interaction, Chain Conformation, and Rheological Modification during Electrospinning of Hyaluronic Acid Aqueous Solution". Membranes 10, n.º 9 (31 de agosto de 2020): 217. http://dx.doi.org/10.3390/membranes10090217.

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Most of natural water-soluble polymers are difficult to electrospin due to their specific chain conformation in aqueous solution, which limits their applications. This study investigated the effects of polyethylene oxide (PEO) on the electrospinning of hyaluronic acid (HA) in HA/PEO aqueous solutions. The rheological properties of HA/PEO aqueous solutions showed polymer chain entanglement in HA was the essential factor affecting its electrospinnability. Wide-angle X-ray scattering and differential scanning calorimetry analyses of a PEO crystal showed different crystallization behavior of the PEO chain with different molecular weight, which indicates different interaction with HA. A schematic molecular model has been proposed to explain the effect of PEO on the chain conformation of HA along with the relationship between electrospinnability and chain entanglement. PEO with a relatively high molecular weight with limited crystal formation formed extensive chain entanglements with HA, while PEO with relatively low molecular weight weakened the interactions among HA chains. The findings of this study provide a wide perspective to better understand the electrospinning mechanisms of natural polyelectrolytes and usage in tissue engineering.

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Russo, Daniela, Andrea de Angelis, Christopher J. Garvey, Frederick R. Wurm, Marie-Sousai Appavou e Sylvain Prevost. "Effect of Polymer Chain Density on Protein–Polymer Conjugate Conformation". Biomacromolecules 20, n.º 5 (abril de 2019): 1944–55. http://dx.doi.org/10.1021/acs.biomac.9b00184.

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Wen, Xiaohui, Deyin Wang, Jiajun Tang e Zhiyong Yang. "A Trefoil Knot Polymer Chain Translocates through a Funnel-like Channel: A Multi-Particle Collision Dynamics Study". Polymers 14, n.º 6 (15 de março de 2022): 1164. http://dx.doi.org/10.3390/polym14061164.

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With combining multi-particle collision dynamics (MPCD) for the solvent and molecular dynamics (MD) for the polymer chains, we have studied the conformation and untying behaviors of a trefoil knot polymer chain translocated through a confined funnel-like channel. For the trefoil knot chain, we found that the untying knot behavior mostly happens during the translocation process, and the translocation behavior of linear chains is also simulated as a comparison. Some characteristics of the trefoil knot chain during translocation process, such as average gyration radius <Rg> and the average end-to-end distances <S> are discussed, and we statistic the scale relations of the translocation time versus the chain length, and that of the chain rigidity. This study may help to understand translocation behaviors of the knotted linear polymer chain in the capillary flow field.

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Maksimova, O. G., A. V. Maksimov e A. I. Moiseeva. "Influence of interface on the formation process of polymer coatings on metal". Journal of Advanced Dielectrics 06, n.º 01 (março de 2016): 1650004. http://dx.doi.org/10.1142/s2010135x16500041.

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The purpose of this work is in development of the model that allows to investigate the conformations of macromolecules near the interface “dielectric-metal” depending on the conditions of formation of the polymer coating. In the modified model of “sticky tape”, one part of macromolecule is anchored to the metal surface while the other can be elongated due to effective mean (molecular) field of dipolar type formed by free ends of other chains. The dynamic Monte-Carlo method for Langmuir’s model is used for calculation of adhesion force taking into account the interaction energy of monomers with the metal surface. It is shown that conformation of polymer chain is defined by temperature conditions of its formation. The obtained results are confirmed by the data of production tests on polymer coatings in JSC “Severstal”.

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Nitneth, David T., James A. Hutchison e Kenneth P. Ghiggino. "Excitonic Processes in a Conjugated Polyelectrolyte Complex". Australian Journal of Chemistry 73, n.º 3 (2020): 164. http://dx.doi.org/10.1071/ch19308.

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In aqueous solution, a di-sulfonated phenylenevinylene polymer (DPS-PPV) forms a complex with non-ionic poly(vinyl alcohol) (PVA) leading to absorption spectroscopic shifts and a dramatic (6-fold) increase in DPS-PPV fluorescence intensity. Spectroscopic investigations demonstrate that the complexation with PVA and other neutral polymers results in conformational changes in the DPS-PPV chains that lead to the removal of non-fluorescent energy traps and results in the observed increase in fluorescence in the bulk solution. Single molecule fluorescence measurements of DPS-PPV chains dispersed on glass and in PVA films confirm that efficient exciton energy transfer occurs within each photo-excited DPS-PPV chain and that the observed increase in fluorescence intensity in the PVA film environment is also associated with fewer quenching sites. The results highlight the importance of conjugated polyelectrolyte conformation on exciton relaxation pathways.

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Cui, Lin Lin, e Hua Nan Guan. "Computer Simulation on Conformation Properties of Polymer Chain". Applied Mechanics and Materials 341-342 (julho de 2013): 195–98. http://dx.doi.org/10.4028/www.scientific.net/amm.341-342.195.

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The author adopts Monte Carlo compute method to simulate the linear polymer chain lattice model in multiple chain systems of chain lengthn=20, 50, 100 while the volume fraction Φ=0.125, and makes a research on the variational situation of the size (measured with the mean-square end-to-end distance <R2> and the mean-square radius of gyration <S2>), shape (measured with the mean asphericity factor <A>) with changing of the interaction energy between solvent molecule and polymer chain segment molecule εPS. Results indicate <R2>, <S2> and <A> have the changing rules that they become small with the increase of the εPS

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Xiao, Hongyi, Xinghua Zhang e Dadong Yan. "A Local-Exchange Model of Folding Chain Surface of Polymer Crystal Based on Worm-Like Chain Model within Single-Chain in Mean-Field Theory". Polymers 12, n.º 11 (30 de outubro de 2020): 2555. http://dx.doi.org/10.3390/polym12112555.

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The structure of amorphous layer of folding surface controls the properties of the polymer lamellar crystal, which consists of chains with a loop conformation. The surface tension depends on the length and the distance between two injection points of the loop which involving the reptation motion and lateral exchange motion of the stems. In the present work, a local-exchange motion model based on the worm-like chain model is developed to investigate the effects of lateral motion of stems on the release the surface tension. The optimal distance between two injection points is determined by the balance of chain bending energy and conformational entropy. The numerical results provide evidences to the adjacent re-entry model for various loop lengths. A possible explanation involving density of injection points is proposed to interpret the mechanism.

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Jacobson, David R., Dustin B. McIntosh, Mark J. Stevens, Michael Rubinstein e Omar A. Saleh. "Single-stranded nucleic acid elasticity arises from internal electrostatic tension". Proceedings of the National Academy of Sciences 114, n.º 20 (1 de maio de 2017): 5095–100. http://dx.doi.org/10.1073/pnas.1701132114.

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Understanding of the conformational ensemble of flexible polyelectrolytes, such as single-stranded nucleic acids (ssNAs), is complicated by the interplay of chain backbone entropy and salt-dependent electrostatic repulsions. Molecular elasticity measurements are sensitive probes of the statistical conformation of polymers and have elucidated ssNA conformation at low force, where electrostatic repulsion leads to a strong excluded volume effect, and at high force, where details of the backbone structure become important. Here, we report measurements of ssDNA and ssRNA elasticity in the intermediate-force regime, corresponding to 5- to 100-pN forces and 50–85% extension. These data are explained by a modified wormlike chain model incorporating an internal electrostatic tension. Fits to the elastic data show that the internal tension decreases with salt, from >5 pN under 5 mM ionic strength to near zero at 1 M. This decrease is quantitatively described by an analytical model of electrostatic screening that ascribes to the polymer an effective charge density that is independent of force and salt. Our results thus connect microscopic chain physics to elasticity and structure at intermediate scales and provide a framework for understanding flexible polyelectrolyte elasticity across a broad range of relative extensions.

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Potai, Ruttayapon, e Rakchart Traiphol. "Effect of Solvents on Controlling the Photophysical Properties of Poly[2-Methoxy-5-(2’-Ethylhexyloxy)-1,4-Phenylenevinylene] (MEH-PPV) Nanoparticle". Nano Hybrids and Composites 16 (junho de 2017): 56–59. http://dx.doi.org/10.4028/www.scientific.net/nhc.16.56.

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Abstract. This study focuses on detailed investigation of solvent effects on controlling photophysical properties of poly [2-methoxy,5-(2’-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) nanoparticles prepared by using reprecipitation techniques. In this work, the MEH-PPV polymer is dissolved in various solvents, including chlorobenzene (CRB), toluene (TOL) and pyridine (PYR). The polymers in solutions adopt different conformations (i.e. collapsed or extended coils), depending on local polymer-solvent interactions. The differences of chain conformations cause the variations of chain packing within the nanoparticles. The majority of nanoparticles exhibit diameter of about 65-70 nm. The photophysical properties of MEH-PPV nanoparticles varied with type of solvents. The absorption spectra of nanoparticles exhibit a broad pattern with a long red tail at about 550 nm, indicating the formation of inter-and/or intrachain aggregates within the nanoparticles. However, the nanoparticle from TOL system shows blueshift of λmax, corresponding to the decrease of conjugation length due to the existence of collapsed coil. The photoluminescence (PL) spectra of MEH-PPV nanoparticles show consistent result with the shift of λmax to about 590 nm and vibronic shoulder at about 640 nm. The PL patterns vary with the type of solvents. In addition, the PL patterns depend on the variations of excitation wavelengths. These discrepancies indicated the variation of chain conformation and degree of aggregation within the nanoparticles. Our results demonstrate the simple method to prepare the conjugated polymer nanoparticle with different photophysical properties by changing solvents.

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Carrillo, Jan-Michael Y., Wei-Ren Chen, Zhe Wang, Bobby G. Sumpter e Yangyang Wang. "Chain conformation of polymer melts with associating groups". Journal of Physics Communications 3, n.º 3 (6 de março de 2019): 035007. http://dx.doi.org/10.1088/2399-6528/ab09bb.

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Gafurov, Ulmas. "Modelling of Elastic Modulus and Molecular Structure Interrelationship of an Oriented Crystalline Polymer". Solid State Phenomena 139 (abril de 2008): 119–22. http://dx.doi.org/10.4028/www.scientific.net/ssp.139.119.

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A modeling method is suggested on the basis of measurable structural and deformation parameters to estimate the interrelation between the interconnecting chains over amorphous segments conformation structure distribution and the elastic modulus in tension experimental value for a loaded oriented linear amorphous- crystalline polymer. Macromolecule chain pulling out value of polymer crystallite was defined using the Frenkel-Kontorowa’s dislocation model .

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Wiśniewska, Małgorzata. "Temperature effects on the adsorption of polyvinyl alcohol on silica". Open Chemistry 10, n.º 4 (1 de agosto de 2012): 1236–44. http://dx.doi.org/10.2478/s11532-012-0044-z.

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AbstractThe influence of temperature on the adsorption of polyvinyl alcohol (PVA) on a silica surface was studied from 15–35°C. The structure of the polymer adsorption layer was determined from spectrophotometric, viscosity and thermogravimetric measurements. The amount of PVA adsorbed, macromolecules’ conformation in solution, thickness of the polymer adsorption layer, and changes in the heating curve of SiO2 with adsorbed polymer were determined. Temperature influences the PVA chain conformation in solution and the structure of the polymer adsorption layer. A temperature rise causes relaxation of polymer coils which results in an increase in the linear dimensions of PVA chains in the solution, the creation of a thicker adsorption layer, and an increase in polymer adsorbed. Polymer adsorption on the silica surface also causes changes in the heating curve of these systems. The mass losses due to heating are smallest for the systems obtained at 15°C because the least polymer is adsorbed at this temperature.

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Li, Xuejuan, Dan Wang e Tareq Saeed. "MULTI-SCALE NUMERICAL APPROACH TO THE POLYMER FILLING PROCESS IN THE WELD LINE REGION". Facta Universitatis, Series: Mechanical Engineering 20, n.º 2 (28 de julho de 2022): 363. http://dx.doi.org/10.22190/fume220131021l.

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In this paper, a multi-scale coupling mathematical model is suggested for simulating the polymer filling process in the weld line region on a micro scale. The model considers two aspects: one is the coupling model based on stresses in the whole cavity region; the other is the multi-scale coupling model of continuum mechanics (CM) and the molecular dynamics (MD) in a weldline region. A weak variational formulation is constructed for the finite element method (FEM), which is coupled with the Verlet algorithm based on the domain decomposition technique. Meanwhile, an overlap region is designed so that the FEM and the MD simulations are consistent with each other. The molecular backbone orientation of the whole cavity is illustrated and the position of the weld line is determined by the characteristics of the molecular backbone orientation. Finally, the properties of the polymer chain in the weld line region are studied conformationally and dynamically. The conformational changes and movement process elucidate that the polymer chains undertake stretching, entangling and orientating. Moreover, the effect of the number of chains and melt temperature on the spatial properties of chain conformation are investigated.

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Najmina, Mazaya, Shingo Kobayashi, Rena Shimazui, Haruka Takata, Mayuka Shibata, Kenta Ishibashi, Hiroshi Kamizawa et al. "A Stealthiness Evaluation of Main Chain Carboxybetaine Polymer Modified into Liposome". Pharmaceutics 16, n.º 10 (28 de setembro de 2024): 1271. http://dx.doi.org/10.3390/pharmaceutics16101271.

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Background: Acrylamide polymers with zwitterionic carboxybetaine (CB) side groups have attracted attention as stealth polymers that do not induce antibodies when conjugated to proteins. However, they induce antibodies when modified onto liposomes. We hypothesized that antibodies are produced against polymer backbones rather than CB side groups. Objectives: In this study, we designed and synthesized a polymer employing CB in its main chain, poly(N-acetic acid-N-methyl-propyleneimine) (PAMPI), and evaluated the blood retention of PAMPI-modified liposomes in mice. Results: The non-fouling nature of PAMPI-modified liposomes estimated from serum protein adsorption was found to be not inferior to PCB- and PEG-modified liposomes. However, to our surprise, the PAMPI-modified liposomes showed an instantaneous clearance less than 1 h post-injection, comparable to the naked liposomes. Conclusions: The extent of the blood retention of polymer-modified liposomes cannot be predicted by their susceptibility to serum protein adsorption and semi-flexible conformation.

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Prajinaru, Mihaela, Natalia Hurduc, Silvia Alazaroaie, Otilia Catanescu e Nicolae Hurduc. "Thermal and kinetic characteristics in non-isothermal conditions of some aromatic copolyethers containing an octomethylenic spacer". Open Chemistry 1, n.º 4 (1 de dezembro de 2003): 387–401. http://dx.doi.org/10.2478/bf02475224.

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AbstractThe paper presents a study of the thermal properties of some aromatic polyethers obtained by phase trasfer catalysis technique. The polymes were synthesized starting from 1,8-dichloro-octane and various bisphenols: 4,4′-dihydroxyazobenzene, 4,4′-dihydroxydiphenyl, bisphenol A and 2,7-dihydroxynaphthalene. Molecular simulations were performed in order to obtain supplementary information concerning the chain conformation and inter-chain interactions. The presence of azobenzenic moieties induces high phase transition values, situated near the thermal stability limit. Therefore, the thermogravimetrical study of these polymers is very important for establishing the temperature limits for DSC and optical microscopy studies. All the polymers present a good thermal stability situated above the isotropization values. In these circumstances no special precautions are necessary for the characterization methods of the liquid crystalline behavior. The kinetic characteristics suggest a similar degradation mechanism by successive reactions. The inter-chain interactions do not influence the thermostability of the samples if the polar surface of the polymer is situated below a certain value.

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Huang, Jian-Hua, Dan-Dan Sun e Rong-Xing Lu. "Glass transition and dynamics of semiflexible polymer brushes". Physical Chemistry Chemical Physics 23, n.º 25 (2021): 13895–904. http://dx.doi.org/10.1039/d1cp00089f.

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Evans, Anthony R., Eric S. G. Shaqfeh e Paul L. Frattini. "Observations of polymer conformation during flow through a fixed fibre bed". Journal of Fluid Mechanics 281 (25 de dezembro de 1994): 319–56. http://dx.doi.org/10.1017/s0022112094003137.

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Linear birefringence measurements of dilute and semi-dilute polyisobutylene solutions following flow through a disordered fixed fibre bed of 2.47% solids volume fraction provide both transient and steady measurements of chain deformation. Our results indicate that the flexible polyisobutylene polymers undergo a large conformation change, stretching in the direction of the average flow. This occurs even though the average flow in the bed is a plug flow which would not cause any polymer stretch by itself. The polymer stretch or conformation change increases with the number of chain interactions with bed fibres and ultimately reaches a steady-state value that can be correlated with the pore-size Deborah number (i.e. a characteristic polymer relaxation time divided by a characteristic flow time in the bed pore). Large changes in the polymer conformation are noted for values of the Deborah number, De > 5. In addition, the time to steady state scales with the characteristic flow time within a pore over a large range of Deborah numbers. The pressure drop across the fibre bed was also measured simultaneously with the birefringence measurement and was found to be directly proportional to the birefringence throughout the range of De investigated. Thus, we show empirically, for the first time, that chain elongation, which produces normal stress anisotropy within the fluid, is directly responsible for the increased flow resistance. These findings are then analysed in the light of recent theories for the response of polymer molecules in fixed bed flow fields (Shaqfeh & Koch 1992). It is shown that our results are consistent with the interpretation that these flows are stochastic strong flows, which create an apparent ‘coil-stretch’ transition. After extending the theory of Shaqfeh & Koch to account for the specifics in the experiments, including the bed geometry and statistics as well as the polydispersity of the polymer solutions, it is shown that the theory can predict most of the experimental results both qualitatively and quantitatively.

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Kojima, Chie, Ugir Hossain Sk, Daichi Fukushima, Kotaro Irie, Naotoshi Akazawa, Masafumi Umeda e Takuro Niidome. "Effect of main chain conformation on thermosensitivity in elastin-like peptide-grafted polylysine". RSC Advances 5, n.º 127 (2015): 104900–104906. http://dx.doi.org/10.1039/c5ra23865j.

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Lee, Jaekyo, Youngmu Kim, Shalik Ram Joshi, Min Sang Kwon e Gun-Ho Kim. "Tacticity-dependent cross-plane thermal conductivity in molecularly engineered amorphous polymers". Polymer Chemistry 12, n.º 7 (2021): 975–82. http://dx.doi.org/10.1039/d0py01549k.

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The present study demonstrated that not only chain extension but also torsion of repeating units and steric hindrance should be considered when designing a thermally conductive polymer by extended chain conformation.

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Gao, Fei, e Lisa M. Weiland. "A multiscale model applied to ionic polymer stiffness prediction". Journal of Materials Research 23, n.º 3 (março de 2008): 833–41. http://dx.doi.org/10.1557/jmr.2008.0096.

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A multiscale modeling approach applied to the stiffness prediction of polymers with high cross-link density is discussed. The material of focus in this work is the ionic polymer Nafion®. The approach applies rotational isomeric state theory in combination with a Monte Carlo methodology to develop a simulation model for polymer chain conformation. From this a large number of end-to-end chain lengths between cross links are generated; the probability density function of these lengths is estimated with the most appropriate Johnson family method. This estimation is used in a Boltzmann statistical thermodynamics approach to the multiscale prediction of stiffness. This work addresses the importance of the simulated polymer chain length in the generation of stable predictions. The multiscale prediction is found to be physically reasonable; the approach has the potential of serving as a first-order prediction tool for properties that are experimentally difficult or impossible to measure.

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Weiland, Lisa Mauck, Emily K. Lada, Ralph C. Smith e Donald J. Leo. "Application of Rotational Isomeric State Theory to Ionic Polymer Stiffness Predictions". Journal of Materials Research 20, n.º 9 (setembro de 2005): 2443–55. http://dx.doi.org/10.1557/jmr.2005.0292.

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Presently, rotational isomeric state (RIS) theory directly addresses polymer chain conformation as it relates to mechanical response trends. The primary goal of this work is to explore the adaptation of this methodology to the prediction of material stiffness. This multiscale modeling approach relies on ionomer chain conformation and polymer morphology and thus has potential as both a predictive modeling tool and a synthesis guide. The Mark–Curro Monte Carlo methodology is applied to generate a statistically valid number of end-to-end chain lengths via RIS theory for four solvated Nafion® cases. For each case, a probability density function for chain length is estimated using various statistical techniques, including the classically applied cubic spline approach. It is found that the stiffness prediction is sensitive to the fitting strategy. The significance of various fitting strategies, as they relate to the physical structure of the polymer, are explored so that a method suitable for stiffness prediction may be identified.

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Neumann, S. Ephraim, Junpyo Kwon, Cornelius Gropp, Le Ma, Raynald Giovine, Tianqiong Ma, Nikita Hanikel et al. "The propensity for covalent organic frameworks to template polymer entanglement". Science 383, n.º 6689 (22 de março de 2024): 1337–43. http://dx.doi.org/10.1126/science.adf2573.

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The introduction of molecularly woven three-dimensional (3D) covalent organic framework (COF) crystals into polymers of varying types invokes different forms of contact between filler and polymer. Whereas the combination of woven COFs with amorphous and brittle polymethyl methacrylate results in surface interactions, the use of the liquid-crystalline polymer polyimide induces the formation of polymer-COF junctions. These junctions are generated by the threading of polymer chains through the pores of the nanocrystals, thus allowing for spatial arrangement of polymer strands. This offers a programmable pathway for unthreading polymer strands under stress and leads to the in situ formation of high-aspect-ratio nanofibrils, which dissipate energy during the fracture. Polymer-COF junctions also strengthen the filler-matrix interfaces and lower the percolation thresholds of the composites, enhancing strength, ductility, and toughness of the composites by adding small amounts (~1 weight %) of woven COF nanocrystals. The ability of the polymer strands to closely interact with the woven framework is highlighted as the main parameter to forming these junctions, thus affecting polymer chain penetration and conformation.

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Armistead, J. P., R. R. Price, O. K. Kim e L. S. Choi. "Shear-induced changes in chain configuration of poly(acrylic acid) in dilute solution". Proceedings, annual meeting, Electron Microscopy Society of America 47 (6 de agosto de 1989): 698–99. http://dx.doi.org/10.1017/s0424820100155463.

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Small amounts (less than 30 ppm) of polymer dissolved in solution may significantly reduce the work required to pump fluids through a pipe at a given rate. In other words, the drag of the solution along the pipe walls is reduced. Drag reduction by polymers has been well characterized, however the molecular origin of the phenomena is not fully understood. Polymers that exhibit drag reduction characteristics typically have high molecular weight, have predominantly linear, flexible chains, and have an expanded molecular configuration in solution.Work in this laboratory has focused on the drag reduction behavior of poly(acrylic acid), PAA, in recent years. This polymer is one of the most shear stable water-soluble polymers and due to the ionic groups in the polymer chain its conformation in solution changes with pH and ionic strength. In a recent work, PAA solutions of 18 ppm, pH=8.1, showed an initial drag reduction of over thirty-five percent in rotating disc experiments. Over four minutes of shearing the drag reduction decreased to ten percent. This was surprising because of the known shear stability of PAA. When the sheared solution was left undisturbed for two weeks, it did not recover its drag reduction performance. However, the addition of NaCl to the solution during the shearing immediately restored drag reduction to its initial level. It was hypothesized that the shear flow induced interchain association that was possibly stabilized by hydrogen bonding and that the addition of the NaCl caused dissociation and drag reduction recovery. In additional work, fluorescence probe studies showed that shear flow induced local chain rigidity in the originally flexible polymer chains. In this study, the drag reduction experiments were repeated and the configurations of the sheared and unsheared polymer chains were viewed using electron microscopy.

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Capaldi, Xavier, Zezhou Liu, Yuning Zhang, Lili Zeng, Rodrigo Reyes-Lamothe e Walter Reisner. "Probing the organization and dynamics of two DNA chains trapped in a nanofluidic cavity". Soft Matter 14, n.º 42 (2018): 8455–65. http://dx.doi.org/10.1039/c8sm01444b.

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We determine the degree of partitioning/mixing in two-polymer confinement in nanofluidic cavities and assess coupled diffusion of the chain center-of-mass positions finding that polymer dynamics and conformation are strongly affected.

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41

Das, S., M. Lange e A. Cacciuto. "Designing active colloidal folders". Journal of Chemical Physics 156, n.º 9 (7 de março de 2022): 094901. http://dx.doi.org/10.1063/5.0081071.

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Can active forces be exploited to drive the consistent collapse of an active polymer into a folded structure? In this paper, we introduce and perform numerical simulations of a simple model of active colloidal folders and show that a judicious inclusion of active forces into a stiff colloidal chain can generate designable and reconfigurable two-dimensional folded structures. The key feature is to organize the forces perpendicular to the chain backbone according to specific patterns (sequences). We characterize the physical properties of this model and perform, using a number of numerical techniques, an in-depth statistical analysis of structure and dynamics of the emerging conformations. We discovered a number of interesting features, including the existence of a direct correspondence between the sequence of the active forces and the structure of folded conformations, and we discover the existence of an ensemble of highly mobile compact structures capable of moving from conformation to conformation. Finally, akin to protein design problems, we discuss a method that is capable of designing specific target folds by sampling over sequences of active forces.

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Wasem Klein, Felipe, Jean-Philippe Lamps, Matthieu Paillet, Pierre Petit e Philippe J. Mésini. "Synthesis of a Poly(3-dodecylthiophene) Bearing Aniline Groups for the Covalent Functionalization of Carbon Nanotubes". Reactions 2, n.º 4 (11 de novembro de 2021): 473–85. http://dx.doi.org/10.3390/reactions2040030.

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The functionalization of carbon nanotubes by polymers necessitates two steps, first their modification by oxidizing them or by covalently attaching small compounds to them, then the growth of the polymer chains from these anchors or their grafting onto them. In order to better control the process and the rate of functionalization, we develop polymers able to covalently react with the carbon nanotubes by their side chains in one step. We describe the synthesis of a copolymer of dodecylthiophene and its analogue bearing an aniline group at the end of the dodecyl side chain. This copolymer can functionalize single-walled carbon nanotubes (SWNTs) non-covalently and disperse more SWNTs than its hexyl analogues. UV-Vis and fluorescence spectroscopies show that in these non-covalent hybrids, the polymer forms p-stacked aggregates on the SWNTs. The non-covalent hybrids can be transformed into covalent ones by diazonium coupling. In these covalent hybrids the polymer is no longer p-stacked. According to Raman spectroscopy, the conformation of the poly(3-hexylthiophene) backbone is more ordered in the non-covalent hybrids than in the covalent ones.

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Mogbojuri, Gabriel, Shaghayegh Abtahi, Nayanathara Hendeniya e Boyce Chang. "The Effects of Chain Conformation and Nanostructure on the Dielectric Properties of Polymers". Materials 18, n.º 1 (5 de janeiro de 2025): 198. https://doi.org/10.3390/ma18010198.

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The dielectric properties of polymers play a pivotal role in the development of advanced materials for energy storage, electronics, and insulation. This review comprehensively explores the critical relationship between polymer chain conformation, nanostructure, and dielectric properties, focusing on parameters such as dielectric constant, dielectric loss, and dielectric breakdown strength. It highlights how factors like chain rigidity, free volume, molecular alignment, and interfacial effects significantly influence dielectric performance. Special emphasis is placed on the impact of nanofillers, molecular weight, crystallinity, and multilayer structures in optimizing these properties. By synthesizing findings from recent experimental and theoretical studies, this review identifies strategies to enhance energy efficiency, reliability, and mechanical stability of polymer-based dielectrics. We also delve into techniques such as electrostatic force microscopy (EFM) and focused ion beam (FIB) milling for characterizing breakdown mechanisms, offering insights into molecular design for next-generation high-performance polymers. Despite considerable progress, critical challenges such as achieving an optimal balance between dielectric permittivity and breakdown strength, understanding nanoscale interfacial phenomena, and scaling these materials for industrial applications persist. These gaps can be addressed by systematic structure–property relations, advanced processing techniques, and environmental studies.

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Cui, Lin Lin, e Hua Nan Guan. "Monte Carlo Simulation on Conformation Properties of Polymer Multiple Chain System". Advanced Materials Research 734-737 (agosto de 2013): 3141–44. http://dx.doi.org/10.4028/www.scientific.net/amr.734-737.3141.

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The author adopts Monte Carlo compute method to simulate the linear polymer chain lattice model in multiple chain systems of different volume fraction Φ while chain lengthn=50, and makes a research on the variational situation of the size (measured with the mean-square end-to-end distance <R2> and the mean-square radius of gyration <S2>), shape (measured with the mean asphericity factor ) with changing of the interaction energy between solvent molecule and polymer chain segment moleculeεPS. Results indicate <R2>, <S2> and have the changing rules that they become small with the increase of theεPS.

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Štokrová, Štěpánka, Jan Pospíšek, Jaroslav Šponar e Karel Bláha. "Synthesis and conformation of sequential basic polypeptides with branched and linear side chains". Collection of Czechoslovak Chemical Communications 50, n.º 12 (1985): 2925–36. http://dx.doi.org/10.1135/cccc19852925.

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Polypeptides (Lys-X-Ala)n and (Lys-X-Gly)n in which X represents residues of isoleucine and norleucine, respectively, and polypeptide (Tle-Lys-Ala)n, were synthesized via polymerization of 1-hydroxysuccinimidyl esters of the appropriate tripeptides to complete previously studied series. Circular dichroism (CD) spectra of the respective polymers were measured as a function of pH and salt concentration of the medium. The results were correlated with those obtained previously with the same series containing different amino acid residues at the X-position. The helix forming ability of the polypeptides (Lys-X-Ala)n with linear X side chain was found to be independent of the length. In the series (Lys-X-Gly)n the unordered conformation was the most probable one except (Lys-Ile-Gly)n. This polymer assumed the β conformation even in low salt solution at neutral pH. An agreement with some theoretical work concerned with the restriction of conformational freedom of amino acid residue branching at Cβ atom with our experimental results is evident.

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Hurduc, Nicolae, Cristina Damian, Anca Tarus, Violeta Toader e Natalia Hurduc. "Thermal behavior of some aromatic copolyethers containing a propylenic spacer". Open Chemistry 3, n.º 1 (1 de março de 2005): 53–62. http://dx.doi.org/10.2478/bf02476237.

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AbstractThe main objective of this paper is to study the thermal stability of some aromatic copolyethers containing a propylenic spacer. Some of the investigated copolyethers displayed a liquid crystalline (LC) behavior, with the presence of the mesogenic groups in the main chain, inducing high values of the thermal transition temperatures. As a consequence, a thermal stability study was necessary to establish the maximum temperature value for the LC behavior characterization. A thermal degradation mechanism is proposed, taking into consideration the azobenzenic unit as the weakest link in the polymer chain and thus, the starting point of the thermal degradation process. The degradation mechanisms were correlated with the chemical structure and the polarity and conformation of the chains. Conformational analysis was performed using molecular simulations. Freeman-Caroll and Coats-Redfern methods were used to calculate some kinetic characteristics.

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Zhao, Weiwei, Yunlan Su e Dujin Wang. "Synergetic effects of interfacial and spatial confinement in polymer nanocomposites". Modern Physics Letters B 31, n.º 23 (20 de agosto de 2017): 1730003. http://dx.doi.org/10.1142/s0217984917300034.

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Dispersing three-dimensional (3D) nanoparticles as the filler into a polymeric component is known to significantly improve the physicochemical properties of the materials and makes them attractive for industrial applications. There are two main contributions to the underlying enhancement mechanism of polymer nanocomposites (PNCs). The first contribution is linked to the interfacial effect, originating from the interaction between polymer and nanoparticles. The packing density, conformation and orientation of adsorbed chains are significantly altered, which results in an interfacial region with different properties from the bulk. The second contribution is attributed to the spatial effect, introduced by confining polymer chains in a restricted space between/among nanoparticles. These two effects are often correlated. The characteristic behavior of polymer chains confined by nanoparticles has already shown to be quite complicated and hence interesting as compared with that of pure polymers. The broad range of influencing factors including the size, content and surface chemistry of nanoparticles as well as the molecular weight and chain ends of polymers were discussed in this review. The controversial issues such as the segmental dynamics at interface, interfacial architecture and the extent of its impact on the bulk phase were summarized, wishing to produce further understanding of PNCs.

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Лебедев, B. T., H. П. Евлампиева, M. B. Бермешев e A. A. Сжогина. "Структура пленок кремнийзамещенного политрициклононена по данным малоуглового рассеяния нейтронов". Физика твердого тела 60, n.º 10 (2018): 2051. http://dx.doi.org/10.21883/ftt.2018.10.46538.044.

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AbstractPolytricyclononenes are new polymers having high permeability values not only for atmospheric gases, but also gaseous hydrocarbons. Thin films (≤100 μm) used in gas-separation membrane technologies are necessary to be studied to improve the gas transport properties of these polymers. The structure of polytricyclononene films with two vicinal side substituents Si(CH_3)_3 in a monomer unit synthesized via additive polymerization scheme is studied in this work by a small-angle neutron scattering method. As a whole, the amorphous film has a local orientation order due to chain fragments with spiral conformation. The size of the ordered regions is comparable to the length of units correlations in the polymer chain (Kuhn segment) and is 8–9 nm. Free volume and type of voids (pores) formed in the polymer film due to inhomogeneous packing are also found.

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Chen, Shensheng, Emily Olson, Shan Jiang e Xin Yong. "Nanoparticle assembly modulated by polymer chain conformation in composite materials". Nanoscale 12, n.º 27 (2020): 14560–72. http://dx.doi.org/10.1039/d0nr01740j.

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Liu, Gongping, Wei-Song Hung, Jie Shen, Qianqian Li, Yun-Hsuan Huang, Wanqin Jin, Kueir-Rarn Lee e Juin-Yih Lai. "Mixed matrix membranes with molecular-interaction-driven tunable free volumes for efficient bio-fuel recovery". Journal of Materials Chemistry A 3, n.º 8 (2015): 4510–21. http://dx.doi.org/10.1039/c4ta05881j.

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Molecular interactions were constructed to control polymer chain conformation to fabricate mixed matrix membranes with tunable free volumes, exhibiting simultaneously improved butanol permeability and selectivity.

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