Journal articles: 'Reaction systems; Polymer reptation'

1

Semenov, A. N., and M. Rubinstein. "Dynamics of strongly entangled polymer systems: activated reptation." European Physical Journal B 1, no. 1 (January 1998): 87–94. http://dx.doi.org/10.1007/s100510050155.

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FALLER, ROLAND, MATHIAS PÜTZ, and FLORIAN MÜLLER-PLATHE. "ORIENTATION CORRELATION IN SIMPLIFIED MODELS OF POLYMER MELTS." International Journal of Modern Physics C 10, no. 02n03 (May 1999): 355–60. http://dx.doi.org/10.1142/s0129183199000267.

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We investigate mutual local chain order in systems of fully flexible polymer melts in a simple generic bead-spring model. The excluded-volume interaction together with the connectivity leads to local ordering effects which are independent of chain length between 25 and 700 monomers, i.e. in the Rouse as well as in the reptation regime. These ordering phenomena extend to a distance of about 3 to 4 monomer sizes and decay to zero afterwards.

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3

Kolinski, Andrzej, Jeffrey Skolnick, and Robert Yaris. "Does reptation describe the dynamics of entangled, finite length polymer systems? A model simulation." Journal of Chemical Physics 86, no. 3 (February 1987): 1567–85. http://dx.doi.org/10.1063/1.452196.

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4

Oshanin, G. S., and S. F. Burlatsky. "Reaction kinetics in polymer systems." Journal of Statistical Physics 65, no. 5-6 (December 1991): 1109–22. http://dx.doi.org/10.1007/bf01049601.

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Skolnick, Jeffrey, Andrzej Kolinski, and Robert Yaris. "Monte Carlo studies of the long-time dynamics of dense polymer systems. The failure of the reptation model." Accounts of Chemical Research 20, no. 9 (September 1987): 350–56. http://dx.doi.org/10.1021/ar00141a006.

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Feng, Lian-Fang, and Guo-Hua Hu. "Reaction kinetics of multiphase polymer systems under flow." AIChE Journal 50, no. 10 (2004): 2604–12. http://dx.doi.org/10.1002/aic.10253.

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7

Millan, Daniela, Mafalda R. Almeida, Ana F. C. S. Rufino, João A. P. Coutinho, and Mara G. Freire. "Nucleophilic degradation of diazinon in thermoreversible polymer–polymer aqueous biphasic systems." Physical Chemistry Chemical Physics 23, no. 7 (2021): 4133–40. http://dx.doi.org/10.1039/d0cp06086k.

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8

Johnston-Hall, Geoffrey, and Michael J. Monteiro. "Termination in Semi-Dilute and Concentrated Polymer Solutions." Australian Journal of Chemistry 62, no. 8 (2009): 857. http://dx.doi.org/10.1071/ch09089.

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The aim of the present work was to develop a deeper understanding into termination processes in the semi-dilute and concentrated regimes. The study was carried out to examine the effect of termination between linear polystyrene radical chains in linear, four-arm star, and six-arm star polymer systems using the reversible addition–fragmentation chain transfer chain length-dependent termination method. In particular, the power-law dependencies of both chain length and polymer concentration were evaluated in the semi-dilute and concentrated regimes. We found that theoretical predictions based on the blob model were in good agreement with the experimentally observed evolution of the rate coefficient for biomolecular termination, kti,i(x), in the semi-dilute solution regime. In addition, solvent quality was found to decrease with increasing chain length, increasing polymer concentration and as a function of the matrix topology (i.e. for star polymer solutions). In the concentrated solution regime, the role of chain entanglements became evident by determining the conversion-dependent power-law exponent, βgel (where kt ≈ x–βgel), which increased in the order: linear < four-arm star < six-arm star polymer systems. Above the critical chain length ic, termination was found to be primarily conversion-dependent, implying entanglements dominated termination between linear polymeric radicals. Although this may suggest that reptation plays an important role, our data are in disagreement with this theory, suggesting that the polymer matrix cannot be regarded as static or immobile on the diffusion time scales for bimolecular termination.

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von Meerwall, Ernst D. "Pulsed and Steady Field Gradient NMR Diffusion Measurements in Polymers." Rubber Chemistry and Technology 58, no. 3 (July 1, 1985): 527–60. http://dx.doi.org/10.5254/1.3536078.

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Abstract Some twenty years after the development of the steady and pulsed gradient spin-echo NMR methods of measuring self-diffusion, these techniques are now maturing and experiencing a surge of interest, much of it concentrated on polymer systems. The methods are briefly reviewed here, together with the most important results in polymers, with particular concentration on work described within the last few years. The research is divisible into three categories: diffusion of diluent and penetrant molecules in rubbery high polymers, diffusion of polymer molecules in dilute and semidilute solutions with liquid solvents, and diffusion of macromolecules dissolved in concentrated solutions or melts of equivalent or different polymers of arbitrary molecular weight. The review includes the main theoretical interpretations of the experiments, particularly the free-volume theory in its various forms and power-law behaviors postulated by recent refinements of tube/reptation and scaling theory. This article represents an updated elaboration of an earlier review.

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Lísal, Martin, John K. Brennan, and William R. Smith. "Mesoscale simulation of polymer reaction equilibrium: Combining dissipative particle dynamics with reaction ensemble Monte Carlo. I. Polydispersed polymer systems." Journal of Chemical Physics 125, no. 16 (October 28, 2006): 164905. http://dx.doi.org/10.1063/1.2359441.

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Ebara, Mitsuhiro, and Takao Aoyagi. "Photo-induced Control of Smart Polymer Systems via pH Jump Reaction." Journal of Photopolymer Science and Technology 27, no. 4 (2014): 467–69. http://dx.doi.org/10.2494/photopolymer.27.467.

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KURODA, Takayuki, Keigo TORIKAI, Hideko T. OYAMA, Toshiaki OUGIZAWA, Takashi INOUE, and Martin WEBER. "Visualized Polymers. Patterns Formed by Polymeric Systems. II. Reaction-Induced Pattern Formation at the Polymer-Polymer Interface." KOBUNSHI RONBUNSHU 56, no. 12 (1999): 860–64. http://dx.doi.org/10.1295/koron.56.860.

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13

Ribeiro, M. C. S., J. A. Rodrigues, António J. M. Ferreira, and António Torres Marques. "Fire Behaviour Enhancement of Epoxy Polymer Mortars Modified with Flame Retardant Systems." Materials Science Forum 587-588 (June 2008): 903–7. http://dx.doi.org/10.4028/www.scientific.net/msf.587-588.903.

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In the present study, fire reaction improvement of an epoxy polymer mortar (PM) formulation, induced by polymer modification with three different flame retardant (FR) systems, was analyzed and quantified. For this purpose, several epoxy PM formulations, modified with different contents and/or types of phosphate, metal hydroxide and brominated based FR systems, were manufactured and tested for both, fire reaction and flexural strength. The results were compared with those of plain epoxy PMs. Fire reaction of PM formulations was assessed by means of the Oxygen Consumption Calorimeter test, also known as Cone Calorimeter test. This test allows the determination of the main parameters that assess fire reaction behaviour of combustible materials: heat release rate, smoke extinction area, carbon dioxide and monoxide release rates, and ignitability. Test results revealed that all FR systems, in particular the phosphate based one, are effective in improving fire reaction performance of epoxy PMs. Moreover, this improvement is attained without significant losses of bearing carrying capacity of PM materials.

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14

Colmenero, J. "Universal Trend of the Non-Exponential Rouse Mode Relaxation in Glass-Forming Polymers Systems: Experimental Facts, MD-Simulation Results and a Theoretical Approach Based on a Generalized Langevin Equation." MRS Advances 1, no. 26 (2016): 1903–13. http://dx.doi.org/10.1557/adv.2016.54.

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ABSTRACTNowadays there are clear evidences from both experiments and MD-simulations proving that the chain Rouse modes correlation functions are non-exponential in unentangled polymer blends and also in pure polymers at low temperature (with respect to that of the glass transition Tg) even for the long wavelengths modes where local potentials and chain stiffness should not play any role. In a recent paper [S. Arrese-Igor et al, Phys. Rev. Lett.113, 078302 (2014)] it has been proposed that this non-exponential behavior depends on the ratio between the so-called Rouse time - i.e., the characteristic time of the slowest chain mode relaxation - and the time scale of the α-relaxation. This parameter is in some way ‘universal’ in the meaning that it can encode many different experimental situations. In this paper, we show that this behavior can be quantitatively explained in the framework of a theoretical approach based on: (i) a generalized Langevin equation (GLE) formalism and (ii) a memory function which takes into account the effect of collective dynamics on the chain dynamics of a tagged chain and which was constructed taking inspirations from the original ideas of the reptation model proposed by de Gennes.

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15

Xu, Guohe, Hongwei Zhou, Jie Li, Lv Yin, Zhaohui Zheng, and Xiaobin Ding. "Autonomous fluorescence regulation in responsive polymer systems driven by a chemical oscillating reaction." Polymer Chemistry 7, no. 19 (2016): 3211–15. http://dx.doi.org/10.1039/c6py00510a.

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16

Abis, Laura, Nikolaos Dimitritatos, Meenakshisundaram Sankar, Simon J. Freakley, and Graham J. Hutchings. "The Effect of Polymer Addition on Base Catalysed Glycerol Oxidation Using Gold and Gold–Palladium Bimetallic Catalysts." Topics in Catalysis 63, no. 3-4 (December 17, 2019): 394–402. http://dx.doi.org/10.1007/s11244-019-01212-y.

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Abstract The oxidation of glycerol represents both a viable route to catalytic upgrading of biomass and has become a model reaction for catalytic polyol oxidation. Gold and gold–palladium nanoparticle catalysts prepared by colloidal methods involving polymer additives have been extensively studied. However, the effect of residual polymer at the catalyst surface on reaction pathways has not been decoupled from particle size effects. We show that when using catalysts prepared without polymer stabilisers the addition of either polyvinyl alcohol or polyvinylpyrrolidone to the reaction changes the reaction rate and results in a change in reaction selectivity. We conclude that the polymer additive has a significant effect on the reaction pathway and that these systems should be considered as a metal surface–polymer interface catalytic systems and properties should not be rationalised solely based on nanoparticle size. Graphic Abstract

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17

Sousa, Susana P. B., Maria C. S. Ribeiro, Paulo R. O. Nóvoa, Celeste M. Pereira, and António J. M. Ferreira. "Polymer Composite Materials Modified with Nano-Oxides and Phosphinates Hybrid Flame Retardant Systems." Key Engineering Materials 634 (December 2014): 527–36. http://dx.doi.org/10.4028/www.scientific.net/kem.634.527.

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Unsaturated polyester based composites materials present several improved properties over conventional materials. However, these composites show great sensitivity to high temperatures and poor fire behaviour. In the present study, an effort is undertaken to develop new unsaturated polyester composites with improved fire reaction behaviour by matrix modification with hybrid flame retardant systems based on nanooxides and phosphinates. For this purpose, a series of composite formulations containing different contents and types of both metal oxide nano/micro particles and organic phosphinates were manufactured, with basis on the Taguchi L9 orthogonal array, and tested for fire reaction and mechanical properties. The data treatment was carried out through analyses of variance. Fire reaction properties were analysed and quantified by the vertical flammability test (UL-94), and the mechanical properties were studied by flexural, Shore D, and Charpy impact tests. The results were compared with those obtained for plain resin specimens. Test results revealed that the addition of hybrid flame retardant systems introduced reasonable improvements in at least one fire reaction property. However, it was verified that the filler addition led to a decrease in mechanical properties, probably due to poor matrix-filler adhesion. Further studies are required in order to improve the mix design formulations.

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18

Liu, Aijie, Cheuk-Wai Tai, Kateřina Holá, and Haining Tian. "Hollow polymer dots: nature-mimicking architecture for efficient photocatalytic hydrogen evolution reaction." Journal of Materials Chemistry A 7, no. 9 (2019): 4797–803. http://dx.doi.org/10.1039/c8ta12146j.

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19

Zhou, Hongwei, Zhaohui Zheng, Qiguan Wang, Guohe Xu, Jie Li, and Xiaobin Ding. "A modular approach to self-oscillating polymer systems driven by the Belousov–Zhabotinsky reaction." RSC Advances 5, no. 18 (2015): 13555–69. http://dx.doi.org/10.1039/c4ra13852j.

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20

Lamnawar, Khalid, Anne Baudouin, and Abderrahim Maazouz. "Interdiffusion/reaction at the polymer/polymer interface in multilayer systems probed by linear viscoelasticity coupled to FTIR and NMR measurements." European Polymer Journal 46, no. 7 (July 2010): 1604–22. http://dx.doi.org/10.1016/j.eurpolymj.2010.03.019.

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21

Berrod, Quentin, Karine Lagrené, Jacques Ollivier, and Jean-Marc Zanotti. "Inelastic and quasi-elastic neutron scattering. Application to soft-matter." EPJ Web of Conferences 188 (2018): 05001. http://dx.doi.org/10.1051/epjconf/201818805001.

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Microscopic dynamical events control many of the physical processes at play in condensed matter: transport, magnetism, catalysis and even function of biological assemblies. Inelastic (INS) and Quasi-Elastic Neutron Scattering (QENS) are irreplaceable probes of these phenomena. These experimental techniques reveal the displacements of atoms and molecules over distances spanning from angstroms to a few tens of nanometers, on time scales ranging from a fraction of picoseconds to microseconds. In this context, the different INS and QENS machines (Time-of-Flight (ToF), Backscattering (BS) and Neutron spin-echo (NSE)) stand at a central position. After introducing an underlying basic theoretical toolbox for neutron scattering, the principles and key elements of a ToF measurement are described. While, here, we mainly focus on disk choppers spectrometers, all the INS/QENS instruments share a common ground: they directly and simultaneously probe correlation functions in both time and space, so that the scattering vector (Q) dependence of the systems characteristic time(s) can be measured. To illustrate, the potentialities of the technique in the field of soft-matter, we show a multiscale approach of the dynamics of a polymer melt. The system is probed from the molecular to the mesoscopic scale (1 ps to 0.6 μs and 0.1 to 40 nm), in bulk and under nanometric confinement. We address the different dynamical modes of a high mass entangled polymer chain: local monomer dynamics, Rouse modes up to the reptation process. This study exemplifies that, used in conjunction with hydrogen/deuterium isotopic effects, high resolution QENS can be bridged to the Zero Average Contrast (ZAC) method to probe, in a non destructive way, the dynamics of a single polymer chain in bulk but also under severe nanometric confinement. Connection and complementarity of the neutron derived analysis with Pulsed-Field Gradient and Relaxation NMR techniques are discussed.

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22

Isakova, Anna, Billy J. Murdoch, and Katarina Novakovic. "From small molecules to polymeric catalysts in the oscillatory carbonylation reaction: multiple effects of adding HI." Physical Chemistry Chemical Physics 20, no. 14 (2018): 9281–88. http://dx.doi.org/10.1039/c7cp07747e.

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23

Sandzhieva, A. V., A. V. Bakhtina, А. А. Sivaev, L. Yu Basyreva, S. A. Gusev, and I. A. Gritskova. "WAYS OF IMPROVING THE SPECIFICITY OF THE LATEX AGGLUTINATION REACTION." Fine Chemical Technologies 11, no. 2 (April 28, 2016): 17–22. http://dx.doi.org/10.32362/2410-6593-2016-11-2-17-22.

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The article describes research on the development of new diagnostic test systems operating on the basis of latex agglutination reaction, in which polymer microspheres are used as bioligand carriers instead of erythrocytes. Polymeric microspheres to be used as bioligand carriers must satisfy the following requirements: narrow size distribution, diameter of 5 microns. Besides, they must be characterized by aggregative stability in water and buffer solutions and be contained functional groups in the surface layer for linking with the functional groups of the protein. They are crosslinked particles obtained by copolymerization of styrene and divinylbenzene on polystyrene seed particles 1.5 microns in diameter with a narrow size distribution followed by modification by chloromethylation and amination by ethylenediamine. To increase the hydrophilicity of the surface of the polymer microspheres and to reduce nonspecific adsorption of proteins dextran was immobilized on the surface of the particles by covalent binding with amino groups of particles using Maillard reaction. It was found that diagnostic test systems, where modified dextran particles were used as carriers of the bioligand (Vi-antigen), are characterized by insufficient specificity and require additional modification of the surface of the polymer microspheres to eliminate its non-specific interaction with the surface of the polymer plate used for the latex agglutination reaction. A nonionic surfactant (Tween 80) proposed for the surface modification and used in a certain concentration provides the best reaction specificity.

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Racovita, Stefania, Nicolae Baranov, Ana Maria Macsim, Catalina Lionte, Corina Cheptea, Valeriu Sunel, Marcel Popa, Silvia Vasiliu, and Jacques Desbrieres. "New Grafted Copolymers Carrying Betaine Units Based on Gellan and N-Vinylimidazole as Precursors for Design of Drug Delivery Systems." Molecules 25, no. 22 (November 20, 2020): 5451. http://dx.doi.org/10.3390/molecules25225451.

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New grafted copolymers possessing structural units of 1-vinyl-3-(1-carboxymethyl) imidazolium betaine were obtained by graft copolymerization of N-vinylimidazole onto gellan gum followed by the polymer-analogous reactions on grafted polymer with the highest grafting percentage using sodium chloroacetate as the betainization agent. The grafted copolymers were prepared using ammonium persulfate/N,N,N′,N′ tetramethylethylenediamine in a nitrogen atmosphere. The grafting reaction conditions were optimized by changing one of the following reaction parameters: initiator concentration, monomer concentration, polymer concentration, reaction time or temperature, while the other parameters remained constant. The highest grafting yield was obtained under the following reaction conditions: ci = 0.08 mol/L, cm = 0.8 mol/L, cp = 8 g/L, tr = 4 h and T = 50 °C. The kinetics of the graft copolymerization of N-vinylimidazole onto gellan was discussed and a suitable reaction mechanism was proposed. The evidence of the grafting reaction was confirmed through FTIR spectroscopy, X-ray diffraction, 1H-NMR spectroscopy and scanning electron microscopy. The grafted copolymer with betaine structure was obtained by a nucleophilic substitution reaction where the betainization agent was sodium chloroacetate. Preliminary results prove the ability of the grafted copolymers to bind amphoteric drugs (cefotaxime) and, therefore, the possibility of developing the new sustained drug release systems.

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25

Uznanski, P., J. Pecherz, and M. Kryszewski. "Photophysical studies of hydrophobically functionalized polyionene systems in aqueous solutions." Canadian Journal of Chemistry 73, no. 11 (November 1, 1995): 2041–46. http://dx.doi.org/10.1139/v95-252.

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Complexes of polyionene and anionic dyes and surfactant were prepared by exchange reaction of counterions in the parent polymer. Fluorescence studies were conducted to observe some characteristic behaviour of these complexes in water Polyionenes with aromatic hydrocarbons adopt an open conformation and there is no evidence for interpolymer interactions. On the contrary, polyionenes with long aliphatic counterions easily form microdomains in aqueous solution due to hydrophobic interaction as evidenced by an increase in excimer emission. Microdomains have an interpolymer nature, as confirmed by measurements of energy transfer from naphthalene to pyrene moieties. Polyionenes with SDS counterions interact with external surfactant molecules and form polymer–surfactant aggregates. Electrostatic repulsions between aggregates dominate on hydrophobic interaction between polymer chains and are responsible for conformational changes. Keywords: hydrophobically modified polymers, surfactants, complexation, fluorescence, nonradiative energy transfer

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26

Yoshida, Yasuyuki, Hiroki Takai, Keisuke Kawahara, Shintaro Mitsumune, Kazuyuki Takata, Akinori Kuzuya, and Yuichi Ohya. "Biodegradable injectable polymer systems exhibiting a longer and controllable duration time of the gel state." Biomaterials Science 5, no. 7 (2017): 1304–14. http://dx.doi.org/10.1039/c7bm00357a.

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27

Radcliffe, Andrew, Rajinder Singh, Kathryn Berchtold, and Fernando Lima. "Modeling and Optimization of High-Performance Polymer Membrane Reactor Systems for Water–Gas Shift Reaction Applications." Processes 4, no. 2 (April 1, 2016): 8. http://dx.doi.org/10.3390/pr4020008.

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28

Sun, Yanping, Hui Liu, Lin Cheng, Shimeng Zhu, Cuifang Cai, Tianzhi Yang, Li Yang, and Pingtian Ding. "Thiol Michael addition reaction: a facile tool for introducing peptides into polymer-based gene delivery systems." Polymer International 67, no. 1 (November 27, 2017): 25–31. http://dx.doi.org/10.1002/pi.5490.

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29

Muller, R., M. Bouquey, F. Mauguière, G. Schlatter, C. Serra, and J. Terrisse. "Rheology of Reactive Polymer Blends: Separation of Mixing and Reatcion Steps." Applied Rheology 11, no. 3 (June 1, 2001): 141–52. http://dx.doi.org/10.1515/arh-2001-0009.

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Abstract The crosslinking reaction in various types of polymer blends was followed by rheological measurements. Miscible polymers with controlled glass transition temperature, chain length and number of functional units per chain were synthesized by bulk radical copolymerization. Other experiments were carried out on immiscible systems based on commercial polymers. Blends were either prepared in a batch mixer or directly in the parallel-plate geometry of a rotational rheometer. Due to the low glass transition or melting temperature of most blend components, it was usually possible to separate the mixing step which was carried out at low temperature from the crosslinking reaction which was followed by small amplitude dynamic measurements at higher temperatures. The influence of several parameters on the reaction was studied, in particular : the reaction temperature, the amount of shear during the mixing step (or mixing time), the number of functional units per chain in each blend component and the blend composition. For the miscible blends, a master curve for the dependence of the elastic modulus G’ as a function of reaction time could be drawn for different functionalities and blend compositions.

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30

Ghavidel Darestani, Nasim, Adrianna Tikka, and Pedram Fatehi. "Sulfonated Lignin-g-Styrene Polymer: Production and Characterization." Polymers 10, no. 8 (August 19, 2018): 928. http://dx.doi.org/10.3390/polym10080928.

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Among sustainable alternatives for replacing fossil-based chemicals, lignin is widely available on earth, albeit the least utilized component of biomass. In this work, lignin was polymerized with styrene in aqueous emulsion systems. The reaction afforded a yield of 20 wt % under the conditions of 100 g/L lignin concentration, pH 2.5, 0.35 mol/L sodium dodecyl sulfate concentration, 5 mol/mol styrene/lignin ratio, 5 wt % initiator, 90 °C, and 2 h. The lignin-g-styrene product under the selected conditions had a grafting degree of 31 mol % of styrene, which was determined by quantitative proton nuclear magnetic resonance (NMR). The solvent addition to the reaction mixture and deoxygenation did not improve the yield of the polymerization reaction. The produced lignin-g-styrene polymer was then sulfonated using concentrated sulfuric acid. By introducing sulfonate group on the lignin-g-styrene polymers, the solubility and anionic charge density of 92 wt % (in a 10 g/L solution) and −2.4 meq/g, respectively, were obtained. Fourier-transform infrared (FTIR), static light scattering, two-dimensional COSY NMR, elemental analyses, and differential scanning calorimetry (DSC) were also employed to characterize the properties of the lignin-g-styrene and sulfonate lignin-g-styrene products. Overall, sulfonated lignin-g-styrene polymer with a high anionicity and water solubility was produced.

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Lacoste, C., L. Choplin, P. Cassagnau, and A. Michel. "Rheology Innovation in the Study of Mixing Conditions of Polymer Blends during Chemical Reaction." Applied Rheology 15, no. 5 (October 1, 2005): 314–25. http://dx.doi.org/10.1515/arh-2005-0015.

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Abstract Polymer melts can be mixed with many monomers, plasticizers, antistatics or foaming additives. Properties of such mixtures can change during blending because of chemical reactions like polymerization or crosslinking. The process may be carried out either in stirred tanks, extruders or in motionless mixers. In this paper we focused on the mixing time and the diffusion time of reagent, plasticizer and polymer thanks to rheological tools, and on the way how rheological properties can be studied during chemical reaction in polymer blending. The concept of rheoreactor and Couette analogy were introduced since we have a reactor on our disposal that can mix solution and measure rheological properties without taking sample. This apparatus appears to be an appreciable tool in complement of internal mixers that are specific to polymer blending. For example, we show the importance of the competition between mixing time and reaction time for reactive systems.

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Holczer, E., Z. Fekete, and P. Fürjes. "Surface Modification of PDMS Based Microfluidic Systems by Tensides." Materials Science Forum 729 (November 2012): 361–66. http://dx.doi.org/10.4028/www.scientific.net/msf.729.361.

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The material aspects of a polymer based microfluidic structure were characterised considering the compatibility of the system with bioanalytical applications. The polydimethylsiloxane (PDMS) based channel system is to be integrated in a full polymer photonic biosensor device developed within the European Union project P3SENS (FP7-ICT4-248304). This work is intended to define a modified material composition, which is appropriate to improve both the wettability and the non-specific protein binding characteristics of the PDMS significantly. Triton X-100 (Sigma-Aldrich) surfactant was added to the raw PDMS before polymerisation. The influence of the tenside was studied considering the polymerisation reaction, the surface characteristics and the functional applicability. To test the hydrodynamic behaviour and non-specific protein adsorption on the surfaces, phosphate buffered saline (PBS) solution and fluorescent labelled human serum albumin (HSA) was applied in a microfluidic capillary system.

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El-Zaatari, Bassil M., Abhishek U. Shete, Brian J. Adzima, and Christopher J. Kloxin. "Towards understanding the kinetic behaviour and limitations in photo-induced copper(i) catalyzed azide–alkyne cycloaddition (CuAAC) reactions." Physical Chemistry Chemical Physics 18, no. 36 (2016): 25504–11. http://dx.doi.org/10.1039/c6cp04950h.

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MASSINGHAM, G., R. ARSLANOGLU, F. E. GAUNTLETT, M. S. RIHAWY, R. W. SMITH, A. S. CLOUGH, M. BRADEN, and M. P. PATEL. "SCANNING ION MICROBEAM ANALYSIS OF DIFFUSION IN IN-MOUTH DRUG RELEASE POLYMERS." International Journal of PIXE 15, no. 03n04 (January 2005): 161–67. http://dx.doi.org/10.1142/s0129083505000477.

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With the aim of characterizing polymer-based drug delivery systems a combination of Scanning MeV 3 He microbeam Nuclear Reaction, Backscattering and Particle Induced X-ray Emission (PIXE) techniques has been developed. This, together with gravimetric and UV techniques has been applied to characterize both water infusion and drug effusion for three in-mouth polymer–drug systems. Preliminary results are presented from the exposure of polymers, containing drug at a level of 9% by weight of the dry polymer, to both pure water and a phosphate buffered saline solution at 37°C.

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Harrison, Andrew, Michael P. Zeevi, Christopher L. Vasey, Matthew D. Nguyen, and Christina Tang. "Accelerated Reaction Rates within Self-Assembled Polymer Nanoreactors with Tunable Hydrophobic Microenvironments." Polymers 12, no. 8 (August 7, 2020): 1774. http://dx.doi.org/10.3390/polym12081774.

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Performing reactions in the presence of self-assembled hierarchical structures of amphiphilic macromolecules can accelerate reactions while using water as the bulk solvent due to the hydrophobic effect. We leveraged non-covalent interactions to self-assemble filled-polymer micelle nanoreactors (NR) incorporating gold nanoparticle catalysts into various amphiphilic polymer nanostructures with comparable hydrodynamic nanoreactor size and gold concentration in the nanoreactor dispersion. We systematically studied the effect of the hydrophobic co-precipitant on self-assembly and catalytic performance. We observed that co-precipitants that interact with gold are beneficial for improving incorporation efficiency of the gold nanoparticles into the nanocomposite nanoreactor during self-assembly but decrease catalytic performance. Hierarchical assemblies with co-precipitants that leverage noncovalent interactions could enhance catalytic performance. For the co-precipitants that do not interact strongly with gold, the catalytic performance was strongly affected by the hydrophobic microenvironment of the co-precipitant. Specifically, the apparent reaction rate per surface area using castor oil (CO) was over 8-fold greater than polystyrene (750 g/mol, PS 750); the turnover frequency was higher than previously reported self-assembled polymer systems. The increase in apparent catalytic performance could be attributed to differences in reactant solubility rather than differences in mass transfer or intrinsic kinetics; higher reactant solubility enhances apparent reaction rates. Full conversion of 4-nitrophenol was achieved within three minutes for at least 10 sequential reactions demonstrating that the nanoreactors could be used for multiple reactions.

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Ahmadi, Mostafa, and Sebastian Seiffert. "Efficiency range of the Belousov–Zhabotinsky reaction to induce the self-organization of transient bonds in metallo-supramolecular polymeric systems." Physical Chemistry Chemical Physics 22, no. 26 (2020): 14965–75. http://dx.doi.org/10.1039/d0cp02429e.

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Although reaction parameters offer control over chemical oscillations in a transient metallo-supramolecular polymer gel network system, this does not result in a pronounced self-organization of metallo-supramolecular bonds.

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Ishihara, Kazuhiko, Wei Xin Chen, and Yuuki Inoue. "Bioinspired and Multifunctional Phospholipid Polymer Nanoparticles." Advances in Science and Technology 102 (October 2016): 3–11. http://dx.doi.org/10.4028/www.scientific.net/ast.102.3.

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Photoreactive and cytocompatible polymer nanoparticles for immobilizing and photoinduced releasing proteins were prepared. A water-soluble and amphiphilic phospholipid polymer, poly (2-methacryloyloxyethyl phosphorylcholine (MPC)-co-n-butyl methacrylate (BMA)-co-4-(4-(1-methacryloyloxyethyl)-2-methoxy-5-nitrophenoxy) butyric acid (PL)) (PMB-PL) was synthesized. The PMB-PL underwent a cleavage reaction at the PL unit by photoirradiation at a wavelength of 365 nm. Additionally, the PMB-PL took polymer aggregate in aqueous medium and was used to modify the surface of biodegradable poly (L-lactic acid) (PLA) nanoparticle as an emulsifier. The morphology of the PMB-PL/PLA nanoparticle was spherical and approximately 130 nm in diameter. The carboxylic acid group in the PL unit could be used for immobilization of proteins by covalent bonding. The bound proteins were released by a photoinduced cleavage reaction. Within 60 sec, up to 90% of the immobilized proteins were released by photoirradiation and activity of the protein released in the medium was maintained as well as that the original proteins before immobilization. Octa-arginine (R8) could promote internalization of the protein/PLA/PMB-PL nanoparticles into cells when the R8 was co-immobilized on the nanoparticles. After that, photoirradiation induced protein release from the nanoparticles and proteins distributed more evenly inside cells. From these results, we concluded that PMB-PL/PLA nanoparticles have the potential to be used as smart carriers to deliver proteins to biological systems, such as the inside of living cells.

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Barak-Kulbak, Einav, Kerem Goren, and Moshe Portnoy. "Advantages of polymer-supported multivalent organocatalysts for the Baylis-Hillman reaction over their soluble analogues." Pure and Applied Chemistry 86, no. 11 (November 1, 2014): 1805–18. http://dx.doi.org/10.1515/pac-2014-0721.

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Abstract Immobilization of well-defined catalytic units onto insoluble support promises significant benefits, but frequently results in a reduced activity and selectivity of the heterogenized catalysts. Recently, we showed that introduction of a dendritic spacer between the support and the units could remedy the compromised activity and/or selectivity of heterogenized catalysts and, in particular, of the systems based on N-alkylated imidazoles. These catalysts exhibit an outstanding multivalency effect on the activity in the Baylis-Hillman reaction, while preserving very high chemoselectivity. In order to better understand this remarkable effect, we decided to synthesize and examine soluble analogues of the supported systems. These soluble catalysts display poor chemoselectivity, although it improves with the increase of the dendritic generation. Though the consumption of the limiting aldehyde reactant (conversion) displays the opposite trend, experiments demonstrated that the chemoselectivity is generation-dependent rather than conversion-dependent. A hydrophobic “pocket” effect was implicated as responsible for the differences between the polystyrene-bound and the soluble catalysts. An MS analysis of the crude reaction mixture revealed that the formation of multiple adducts, which incorporate several enone and several nitrobenzaldehyde fragments into a single molecular structure (as opposed to one-to-one stoichiometry of the Baylis-Hillman reaction), is responsible for the decline in the chemoselectivity.

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Gharehkhani, Samira, Weijue Gao, and Pedram Fatehi. "In-Situ Rheological Studies of Cationic Lignin Polymerization in an Acidic Aqueous System." Polymers 12, no. 12 (December 14, 2020): 2982. http://dx.doi.org/10.3390/polym12122982.

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The chemistry of lignin polymerization was studied in the past. Insights into the rheological behavior of the lignin polymerization system would provide crucial information required for tailoring lignin polymers with desired properties. The in-situ rheological attributes of lignin polymerization with a cationic monomer, [2-(methacryloyloxy)ethyl] trimethylammonium chloride (METAC), were studied in detail in this work. The influences of process conditions, e.g., temperature, component concentrations, and shear rates, on the viscosity variations of the reaction systems during the polymerization were studied in detail. Temperature, METAC/lignin molar ratio, and shear rate increases led to the enhanced viscosity of the reaction medium and lignin polymer with a higher degree of polymerization. The extended reaction time enhanced the viscosity attributing to the larger molecular weight of the lignin polymer. Additionally, the size of particles in the reaction system dropped as reaction time was extended. The lignin polymer with a larger molecular weight and Rg behaved mainly as a viscose (tan δ > 1 or G″ > G′) material, while the lignin polymer generated with smaller molecular weight and shorter Rg demonstrated strong elastic characteristics with a tan (δ) lower than unity over the frequency range of 0.1−10 rad/s.

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Gritskova, I. A., A. A. Sivaev, S. A. Gusev, S. M. Levachev, N. A. Lobanova, A. V. Andreeva, and S. N. Chvalun. "Polymer microspheres for replacement of biological carriers in test systems operating on the principle of latex agglutination reaction." Russian Chemical Bulletin 68, no. 11 (November 2019): 2075–82. http://dx.doi.org/10.1007/s11172-019-2668-z.

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Zheng, Dandan, Chenyang Pang, and Xinchen Wang. "The function-led design of Z-scheme photocatalytic systems based on hollow carbon nitride semiconductors." Chemical Communications 51, no. 98 (2015): 17467–70. http://dx.doi.org/10.1039/c5cc07867a.

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Hollow conjugated polymer nanospheres mimicking thylakoids act as a host scaffold that coassemble with CdS and Au as an electron mediator to construct an artificial Z-scheme photosynthesis system, which shows a highly efficient performance in photocatalytic water-splitting and CO₂reduction reaction under the irradiation of visible light.

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Das, Diparjun, Gunindra Pathak, and Lalthazuala Rokhum. "Polymer supported DMAP: an easily recyclable organocatalyst for highly atom-economical Henry reaction under solvent-free conditions." RSC Advances 6, no. 106 (2016): 104154–63. http://dx.doi.org/10.1039/c6ra23696k.

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Polymer supported catalysts are regarded as a borderline class of catalysts, which retains the advantages of homogeneous catalysts while securing the ease of recovery by simple filtration and workup of heterogeneous systems.

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Chang, Huey Ling, Chih Ming Chen, and Cheng Ho Chen. "A Study of Reaction Viscosity Changes in Electronic Packaging with Different Nanoparticle Strengthened Epoxy Matrices." Advanced Materials Research 853 (December 2013): 23–27. http://dx.doi.org/10.4028/www.scientific.net/amr.853.23.

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In this paper, the effects of strengthening epoxy matrices with nanopowders are discussed. Investigate the changes of reaction viscosities after adding different hardeners, nanoparticles and diluents to the polymer matrices. Analyze the applications to the automatic electronic packaging. The results show that different species in the curing reaction systems of epoxy will affect flow stabilities. Reaction viscositiesare affected primarily by the choice of hardeners. Nanoparticles will increase system viscosities and shorten matrix resin gel time. Adding diluents will help spread the powders and material flows in the systems, but is relatively not good for stability.

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Liu, Keyuan, Long Ye, Yao Wang, Ganhong Du, and Liming Jiang. "A Pseudopeptide Polymer Micelle Used for Asymmetric Catalysis of the Aldol Reaction in Water." Polymers 10, no. 9 (September 10, 2018): 1004. http://dx.doi.org/10.3390/polym10091004.

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Micelles assembled from amphiphilic molecules have proved to be ideal scaffolds to construct artificial catalysts mimicking enzymatic catalytic behavior. In this paper, we describe the synthesis of amphiphilic poly(2-oxazoline) derivatives with l-prolinamide units in the side chain and their application in asymmetric aldol reactions. Upon dissolution in water, the pseudopeptide polymers self-assembled into particles with different sizes, relying on the copolymer composition and distribution of hydrophilic/hydrophobic segments in the polymer chain. A preliminary study has demonstrated that the catalytic activity of these polymeric organocatalysts are strongly dependent on the aggregated architecture. The micelle-type assemblies can act as nanoreactors to efficiently promote the direct aldolisation of cyclohexanone with aromatic aldehydes in aqueous media, affording anti-aldol products in excellent yields (88–99%) and higher stereoselectivities (90/10 dr, 86% ee) compared to their nonmicellar systems under identical conditions.

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Parker, Dane K., Howard A. Colvin, Arthur H. Weinstein, and Sun-Lin Chen. "Reactively Curable Rubbers—I: Diene Elastomers with Pendant Isocyanate and/or Hydroxyl Functionality." Rubber Chemistry and Technology 63, no. 4 (September 1, 1990): 582–98. http://dx.doi.org/10.5254/1.3538275.

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Abstract In conclusion, we have demonstrated that modified diene elastomers containing active hydrogens and/or blocked-isocyanate derivatives can be crosslinked (cured) by three distinct methods. These methods include: 1. reaction of polymer-bound active hydrogens with monomeric polyisocyanates (Type I), 2. reaction of polymer-bound isocyanates with compounds containing two or more active hydrogens (Type II), and 3. reaction between polymer segments that contain both polymer-bound isocyanates and active hydrogens (Type III). Additionally, we have shown that the new polymerizable blocked-isocyanate derivatives (Type II and III systems) can be readily incorporated into SBR and NBR elastomers by standard emulsion-polymerization techniques. The degree and distribution of these monomers within the elastomer matrix were shown to be controlled by knowledge of their reactivity ratios. Furthermore, we have shown that the processing and properties of these systems can be readily controlled by the proper combination of isocyanate blocking group, active-hydrogen component, and catalyst. In many cases, these modified elastomers can be coagulated, dried, compounded, and cured using methods common to the rubber industry. Although not optimized, we have also shown that useful vulcanizates can be produced from extremely simple recipes. Conventional acceleration systems e.g., sulfur, accelerator, zinc oxide, are eliminated. The resulting urethane or urea crosslinks are remarkably durable under both thermal and hydrolytic conditions. Obviously, the possibilities for these uniquely reactive elastomers have not been exhausted. Many other intriguing applications of this technology are currently being explored. These applications will be the subject of future publications.

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Bączek, Natalia, Krzysztof Strzelec, and Karolina Wąsikowska. "Magnetic recykling of complex catalysts immobilized on thiol-functionalized polymer supports." Polish Journal of Chemical Technology 15, no. 3 (September 1, 2013): 65–68. http://dx.doi.org/10.2478/pjct-2013-0046.

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Abstract In this work, the application of the thiol-functionalized epoxy resin encapsulated on magnetic core as supports for palladium catalysts is reported. The study focuses on obtaining of heterogeneous catalysts which can be separated by magnetic field. Palladium complex catalyst [PdCl2(PhCN)2] has been heterogenized by anchoring to these supports via ligand exchange reaction. The characterization of polymeric supports and heterogenized palladium catalysts has involved research methods like time-of-flight secondary ion mass spectrometry (TOF-SIMS), scanning electron microscopy (SEM) and nitrogen BET surface area measurements. The activity and stability during long-term use of the investigated catalytic systems were tested in a Heck and hydrogenation reaction. The influence of the type of thiols used as epoxy hardeners and the morphology of the supports on the catalytic properties of epoxy-supported palladium catalysts was discussed.

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Chen, Yu Hang, and Qing Li. "Mathematical Modeling of Polymer Biodegradation and Erosion." Materials Science Forum 654-656 (June 2010): 2071–74. http://dx.doi.org/10.4028/www.scientific.net/msf.654-656.2071.

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The biodegradable polymers are widely used in therapeutic surgery and pharmaceutics, in which the degradation process has drawn significant attention in recent years. In this paper, we propose a mathematical model to predict the polymer degradation in tissue engineering applications. A stochastic model is introduced to characterize the hydrolysis reaction in an elemental basis and the mass transport is also performed to investigate the diffusive transport of polymer erosion. Two representative polymeric films in different configurations are studied. It is found that for biodegradable systems, mass transport plays an important role in controlling the erosion pathway, in which the matrix configuration could be one of the key factors that determine the characteristics of erosion and drug release rates. The proposed model makes a useful benefit to the design optimization of the matrix architectures for biodegradable devices.

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Cazin, Ines, Elisabeth Rossegger, Gema Guedes de la Cruz, Thomas Griesser, and Sandra Schlögl. "Recent Advances in Functional Polymers Containing Coumarin Chromophores." Polymers 13, no. 1 (December 25, 2020): 56. http://dx.doi.org/10.3390/polym13010056.

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Natural and synthetic coumarin derivatives have gained increased attention in the design of functional polymers and polymer networks due to their unique optical, biological, and photochemical properties. This review provides a comprehensive overview over recent developments in macromolecular architecture and mainly covers examples from the literature published from 2004 to 2020. Along with a discussion on coumarin and its photochemical properties, we focus on polymers containing coumarin as a nonreactive moiety as well as polymer systems exploiting the dimerization and/or reversible nature of the [2πs + 2πs] cycloaddition reaction. Coumarin moieties undergo a reversible [2πs + 2πs] cycloaddition reaction upon irradiation with specific wavelengths in the UV region, which is applied to impart intrinsic healability, shape-memory, and reversible properties into polymers. In addition, coumarin chromophores are able to dimerize under the exposure to direct sunlight, which is a promising route for the synthesis and cross-linking of polymer systems under “green” and environment-friendly conditions. Along with the chemistry and design of coumarin functional polymers, we highlight various future application fields of coumarin containing polymers involving tissue engineering, drug delivery systems, soft robotics, or 4D printing applications.

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Mituła, Katarzyna, Michał Dutkiewicz, Julia Duszczak, Monika Rzonsowska, and Beata Dudziec. "Preparation of Tri(alkenyl)functional Open-Cage Silsesquioxanes as Specific Polymer Modifiers." Polymers 12, no. 5 (May 6, 2020): 1063. http://dx.doi.org/10.3390/polym12051063.

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The scientific reports on polyhedral oligomeric silsesquioxanes are mostly focused on the formation of completely condensed T8 cubic type structures and recently so-called double-decker derivatives. Herein, we report on efficient synthetic routes leading to trifunctionalized, open-cage silsesquioxanes with alkenyl groups of varying chain lengths from -vinyl to -dec-9-enyl and two types of inert groups (iBu, Ph) at the silsesquioxane core. The presented methodology was focused on hydrolytic condensation reaction and it enabled obtaining titled compounds with high yields and purity. A parallel synthetic methodology that was based on the hydrosilylation reaction was also studied. Additionally, a thorough characterization of the obtained compounds was performed, also in terms of their thermal stability, melting and crystallization temperatures (TGA and DSC) in order to show the changes in the abovementioned parameters dependent on the type of reactive as well as inert groups at Si-O-Si core. The presence of unsaturated alkenyl groups has a profound impact on the application potential of these systems, i.e., as modifiers or comonomers for copolymerization reaction.

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Roland, C. M. "Interactions in a Miscible Polymer Blend." Rubber Chemistry and Technology 61, no. 5 (November 1, 1988): 866–78. http://dx.doi.org/10.5254/1.3536223.

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Abstract Characterization of blends of atactic poly(vinylethylene) with cis-1,4-poly-isoprene provides unique insights into the factors governing the properties of polymer mixtures. While studies of polymer blends have heretofore focussed on systems in which chemical reaction between the components enabled miscibility, any properties arising from the blending of PVE with PIP are not a result of greater cohesive energy density or densification. It is also interesting to consider the different crosslinking reactivity of the main-chain unsaturation in PIP versus that of the pendant vinyl group of PVE, which can give rise to interesting network properties. These will be the subject of a subsequent communication. While it is clear that the Flory interaction parameter for these blends must be non-negative, direct determination of its magnitude is best accomplished through measurement of small-angle neutron scattering. Currently deuterated polybutadienes of varying microstructure are being synthesized to enable such experiments to be carried out, and thereby allow the effect of vinyl level on the miscibility and phase behavior to be quantified.

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Journal articles on the topic 'Reaction systems; Polymer reptation'

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