Comparison of chain-growth polymerization in solution versus on surface using reactive coarse-grained simulations

POLYMER

卷:129

Article

Deng, Binghui¹  Palermo, Edmund F.¹  Shi, Yunfeng¹ 

[1] Rensselaer Polytech Inst, Dept Mat Sci & Engn, Troy, NY 12180 USA

关键词: Reactive force field;    Surface-initiated polymerization;    Chain distribution;    Dispersity;    Polymer brush;   

DOI  :  10.1016/j.polymer.2017.09.048

来源: Elsevier

【 摘 要 】

We developed a reactive coarse-grained model for chain-growth polymerization to study the chain length distribution of polymers grafted from a surface as compared to those grown in solution. The surface-initiated polymer chains exhibit a markedly broader distribution of chain lengths (larger dispersity) and slower chain growth kinetics as compared to the solution phase process. Two key factors that cause deviation from ideal grafting are identified: (1) the formation of chain loops with both termini attached to the substrate via recombination and (2) the starvation effect, in which the live chain ends of short polymers are sterically shielded from monomers by the presence of longer neighboring chains. Both effects are markedly amplified with increasing initiator surface density, thus limiting the density of high molecular weight chains grafted from the surface. Whereas the loop effect is absent in systems that are very strictly living (no termination), the starvation effect is likely operative in most real systems. Taken together, these results suggest a theoretical limit on the density of polymer brushes that can form on surfaces by a grafting- from technique, based on the kinetics of the chain- growth polymerization process. (C) 2017 Elsevier Ltd. All rights reserved.

【 授权许可】

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