Effect of Athermal Solvency Conditions and Solvent Size on Intra Molecular Chain Transfer to Polymer in Acrylate Radical Polymerization Through Computational Approach

Abstract

The influence of solvent as a true thermodynamics medium effect in the free radical solution polymerization of n-butyl acrylate (n-BA) monomer was studied using density functional theory calculations. Three solvent systems which include cyclohexane, cycloheptane and cyclooctane were considered with B3LYP as a hybrid density functional by using 3-21 Basis set. The activation energy of the n-BA monomer was estimated from measurements of monomer conversion to polymer in free radical solution polymerization. Additionally, a conductor-like polarizable continuum model (C-PCM) was applied on the geometries with three different solvents system in propagating monomer chain. This model has a dramatic effect on all the propagation rates. These studies predict that with the increasing size of solvents, there was a decrease in the activation energy, which can follow same energy trend to result in decrease in the extent of chain transfer to polymer (CTP). Probability of CTP relative to propagation analysis were also carried out and molar fraction branching calculation predicts that polymer chains have tendency toward less branching formation via intramolecular chain transfer to polymer in cyclooctane larger solvent system than other two smaller solvents systems of cyclohexane and cycloheptane.