화학공학소재연구정보센터
Macromolecules, Vol.53, No.12, 4630-4648, 2020
Conformational Distributions near and on the Substrate during Surface-Initiated Living Polymerization: A Lattice-Based Kinetic Monte Carlo Approach
One of the challenges in the field of surface-initiated polymerization (SIP) is gaining access to conformational distributions allowing one to quantify the degree of brush/mushroom character during synthesis. Here, we put forward a novel kinetic Monte Carlo (kMC) tool to be successful in this respect, focusing on chain-to-chain deviations on and near the surface accounting for varying reaction probabilities and combining conventional kMC modeling with a modified version of the bond fluctuation model. The potential of the tool is illustrated for living SIP addressing the effect of shielding on the efficiency of surface initiation and propagation. It is shown that at higher reaction times shielding for propagation leads to the increased formation of hindered shorter chains, causing the formation of a bimodal number chain-length distribution (CLD) for tethered chains compared to the always unimodal number CLD for free larger chains near the surface. Moreover, it can be evaluated at any synthesis time if an individual chain possesses a mushroom, brushlike, or brush conformation. It is demonstrated that an optimal (average) initiator surface coverage exists, leading to a sufficiently high chain grafting density and a maximization of the brush character provided that an initiator with the correct (surface) initiation reactivity is selected. The developed tool is important for the multi-angle design of future SIP processes focusing on optimization in reaction time, control over CLD, and conformational features in view of the desired application.