Group transfer polymerization of biobased monomers

This article overviews the work by our Group at the University of Cyprus on the attempted controlled polymerization of several biobased unsaturated esters. These were esters of tiglic acid, itaconic acid, fumaric acid, maleic acid and methylene malonic acid, whereas the method employed for their polymerization was group transfer polymerization (GTP), a type of quasi-living oxyanionic polymerization, capable of the rapid, room-temperature polymerization of α,β-unsaturated carbonyl compounds. Since the methyl ester of tiglic acid resisted GTP as well as conventional and controlled radical polymerizations, the monomer 2-(tigloyl)ethyl methacrylate was prepared and smoothly (co)polymerized by GTP from the methacrylate functionality, yielding various homopolymers, block copolymers and star polymers of well-defined structure. Although not polymerizable to high conversion by GTP, 1–2 units of di(n-butyl) itaconate could consistently be added to living GTP polymethacrylates, allowing their efficient end-functionalization. Similar observations were also made with diethyl maleate and diethyl fumarate. In contrast, the diethyl ester of the lower homologue of itaconic acid, methylene malonic acid, would spontaneously polymerize, probably via a mechanism of anionic polymerization initiated by moisture.