α,ω‐Dihydroxy telechelic poly(methyl methacrylate) via β‐scission (radical addition‐fragmentation) chain transfer polymerisation by macromonomer chain transfer agents, as prepared by catalytic chain transfer polymerisation

Abstract

Abstractα,ω‐Dihydroxy telechelic poly(methyl methacrylate) has been prepared by β‐scission (radical addition‐fragmentation) chain transfer polymerisation. Hydroxyethyl methacrylate dimer macromonomer prepared from catalytic chain transfer polymerisation and isolated as a pure compound is shown to be an efficient chain transfer agent. The mode of chain transfer is via β‐scission which results in the dimer breaking in half on addition to a propagating poly(methyl methacrylate) radical terminating the polymerisation and providing a hydroxyethyl methacrylate radical which reinitiates polymerisation. A combination of these two events leads to dihydroxy telechelic products, demonstrated to have a functionality of 2.05 by a combination of NMR and size exclusion chromatography (SEC). The chain transfer coefficients of these methacrylic macromonomers is concentration dependant exhibiting a type of “bootstrap” effect. This ultimately leads to a limiting low molecular weight telechelic product by the use of dimeric β‐scission chain transfer agents. A combination of high field NMR and matrix assisted laser desorption time‐of‐flight mass spectrometry has been utilised to demonstrate the structure of the products. The combination of catalytic chain transfer polymerisation and β‐scission chain transfer has been demonstrated to be a powerful tool in the controlled polymerisation of methacrylates by radical methodology.