CHAIN TRANSFER OF VEGETABLE OIL MACROMONOMERS IN SOLUTION POLYMERIZATION

摘要

Using vegetable oil macromonomers (VOMMs) as comonomers in emulsion polymerization enable film coalescence in the absence of externally added cosolvents; eliminating the need for volatile organic compounds (VOCs) in emulsion based coatings. VOMMs are derived from renewable resources and provide post application crosslinking via auto-oxidation. Chain transfer reactions between unsaturated VOMMs and initiator and/or polymer radicals during emulsion polymerization reduce the quantity of allylic hydrogen atoms available for primary auto-oxidation during drying and potentially limit the solvation/plasticization effect provided by VOMM inclusion. In order to quantify the subtle and variable molecular level results of chain transfer during free radical polymerization, solution and emulsion polymerization studies were pursued in combination. In this publication, vegetable oils, fatty acid derivatives, and an oligomeric polyethylene oxide were each reacted with butyl acrylate and methyl methacrylate in solution, and the polymerization was monitored using in situ infrared spectroscopy to determine the extent of chain transfer. Chain transfer increased with increasing concentrations of vegetable oil and was most pronounced when polyunsaturated oils such as soybean oil, linseed oil, and rung oil were present during free radical polymerization. ~1H NMR spectroscopy measured negligible decrease in vegetable oil unsaturation during solution polymerization, which confirms abstraction of allylic hydrogen atoms and double bond preservation simultaneously.