We propose a possible strategy that may experimentally generate long polymeric chains with an entanglement-free structure. The basic idea is designing the conditions to restrict polymer chains from growing along the surface with an obviously concave curvature. This strategy is proved to effectively reduce the chance of forming both inter- and intra-molecular entanglements, which is quite similar to the self-avoiding random walking of chains on a two dimensional plane.
View Article and Find Full Text PDFBy employing dissipative particle dynamics (DPD) simulations combined with stochastic polymerization models, we have conducted a detailed simulation study of supramolecular solution polymerization as well as interfacial polymerization employing a coarse-grained model which is closer to the real monomer structure. By adding bending angle potentials to coarse-grained models representing supramolecular reactive monomers, we achieved monomer model simulations for different kinds of multiple hydrogen bonds. Our simulation results indicated that for the interfacial polymerization system, the volume of the monomer caused a strong steric hindrance effect, which in turn led to a low average degree of polymerization of the product.
View Article and Find Full Text PDFIn this study, using dissipative particle dynamics simulations coupled with the stochastic reaction model, we investigate the polymerization-induced polymer aggregation process and the polymer aggregation-enhanced polymerization process in a binary solution, by simply tuning the solubility of the solvent to one species of copolymerization. Our simulations indicate that it is a complicated interplay of the copolymerization on the formation of aggregates, namely, on one hand the polymerization may induce the aggregation of one species; on the other hand it has an effect of mixing the two species together. We also find that the polymerization process basically follows the first order reaction kinetics.
View Article and Find Full Text PDFBy Brownian dynamics simulations we study the simultaneous polymer chain growth process with the coexistence of bulk and surface initiators. We find that when the surface initiator density is low enough, the practical experimental way to estimate the dispersity (Đ) of surface-initiated chains on the basis of the dispersity of bulk-initiated chains remains valid as long as the conformations of grafted chains remain within the mushroom regime (i.e.
View Article and Find Full Text PDFNanoparticles (NPs) grafted with polymer chains prepared via a grafting-from strategy are studied through coarse-grained molecular dynamics simulations combined with our stochastic reaction model. A system involving multiple individual NPs, with grafting-from processes for all the NPs induced simultaneously, is simulated, so that chain growth competition on the same NP, as well as between neighbouring NPs, are both naturally considered. Our results imply that there should be an optimized range of NP sizes, as compared to monomer size, in which initiator sites are most easily induced.
View Article and Find Full Text PDFKinetic step-growth polymerization is studied by dissipative particle dynamics coupled with our previously developed reaction algorithm on a coarse-grained level. The simulation result proves that this step-growth polymerization obeys the second-order reaction kinetics. We apply this algorithm to study the step-growth polymerization using the subunits with different flexibilities or within confinement.
View Article and Find Full Text PDFBy constructing a grafting-to reaction model of polydispersed polymer chains to bind onto nanoparticles (NPs), we elucidate the changes of grafting density, polydispersity index and chain length distribution of grafted ligand chains as a dependent of the feeding polymer chains. Our study shows a linear dependence of the grafting density on the average chain length of the feeding polymers. We also clearly demonstrate the NP's selectivity of short chains in the later stage of the reaction.
View Article and Find Full Text PDFPhys Chem Chem Phys
December 2015
The polymer-grafted nanoparticles prepared by the surface-initiated polymerization induced from the spherical surface is studied by coarse-grained molecular dynamics simulations combined with the stochastic reaction model. The coupling effect of the initiator density and the grafting surface curvature is mainly investigated. The confinement degree greatly changes with the grafting surface curvature, thus the initiation efficiency, the grafted chain polydispersity, as well as the chain mass distribution show great dependence on the surface curvature.
View Article and Find Full Text PDFWe focus on highly grafted binary polymer brushes with compatible components in the cases of different chain lengths. Layered structures parallel to the surface that indicating "phase separation" are observed in a series of dissipative particle dynamics simulations. The stretch parameters indicate that the short chains are suppressed in the lower layer of the film, whereas the longer chains are much stretched in the region dominated by the short chains (lower layer) but possess relaxed conformations in the upper layer.
View Article and Find Full Text PDFDissipative particle dynamics (DPD) simulation technique is an effective method targeted on mesoscopic simulations in which the interactions between particles are soft. As a result, it inevitably causes bond crossing and interpenetration between particles. Here we develop a practical method based on the two-dimensional DPD model which can extremely reduce the possibility of bond crossing.
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