A Combined Computational and Experimental Study of Copolymerization Propagation Kinetics for 1-Ethylcyclopentyl methacrylate and Methyl methacrylate

Abstract

The crosspropagation of 1-ethylcyclopentyl methacrylate (ECPMA) and methyl methacrylate (MMA) has been studied using a combination of quantum chemistry calculations and experiment. Our computational work utilizes a trimer-to-tetramer reaction model, coupled with an ONIOM (B3LYP/6-31G(2df,p): B3LYP/6-31G(d)) method for geometry optimization and an M06-2X/6-311+G(2df,p) method plus SMD solvation model for single point energy calculations. The results show several trends: the identity of the ultimate unit of a trimer radical affects not only the preferred conformation of the region where the reaction takes place, but also the reactivity of the radical; the addition of an ECPMA monomer to the radicals is generally favored compared to an MMA monomer; the pen-penultimate unit of a trimer radical shows a nonnegligible entropic effect; the penultimate unit effect is implicit for the ECPMA-MMA copolymer system. Finally, terminal model reactivity ratios fi tted based on the explicit rate coeffi cients calculated from the quantum chemical results are compared with those from experimental measurements. The computations not only agree qualitatively with experimentally derived results in terms of the selectivity of ECPMA-MMA crosspropagation, but also give reasonable quantitative predictions of reactivity ratios.

Monomer Structure and Solvent Effects on Copolymer Composition in (Meth)acrylate Radical Copolymerization

“…This is true for simple systems like MMA/DMA, 4 but also for xMA bearing diverse functional groups in their ester side chains such as 2-(2-bromopropionyloxy) propyl methacrylate, 49 AAEMA, 37 or 1-ethylcyclopentyl methacrylate. 50 Furthermore, a variety of xMA/n-alkyl acrylate (xA) pairs consistently produce methacrylate-rich copolymers. 2,3,7,51 For such xMA/xMA and xMA/xA copolymerization systems, it is found that the effect of solvent choice on copolymer composition is small as long as the difference in monomer and solvent polarities is not large.…”