RAFT polymerization and associated reactivity ratios of methacrylate-functionalized mixed bio-oil constituents

Abstract

This work features a new suite of correlations for estimating kinetic parameters from multicomponent reversible addition-fragmentation chain-transfer (RAFT) polymerizations and an improved methodology for determining reactivity ratios in the pursuit of cost-effective and renewable plastics prepared from moderately processed bio-oils. Select monomers representing possible derivatives of compounds found in renewable bio-oils, such as pyrolyzed Kraft lignin and vegetable oils, were polymerized to investigate the consequences of structural diversity on the kinetics of RAFT polymerization. To facilitate predictions of heteropolymer dispersities and molecular weights, apparent chain-transfer coefficients (Capptr's) and propagation rate constants (kappp's) from homopolymerizations were correlated to kinetic parameters associated with the polymerization of bio-oil mixtures. Capptr depended on the reactivity ratios of the bio-oil components and the composition of the bio-oil feed, whereas kappp was related to only the composition of the bio-oil feed. A modified approach for analyzing Mayo-Lewis plots resulted in more accurate reactivity ratios and with greater precision in comparison to conventional nonlinear fitting procedures and traditional linearization fitting methods, respectively. The measured compositional data readily mapped onto the predicted monomer distribution profiles in multicomponent polymers, confirming the validity of the improved method described herein to determine reactivity ratios. Altogether, this manuscript offers a strategy for improving the viability of biobased polymers, addressing two key factors: minimizing separations costs by polymerizing bio-oil mixtures and preventing batch-to-batch inconsistencies in polymer properties by applying a priori knowledge about the bio-oil constituents' individual kinetic parameters.