alpha,omega-Dihydroxy telechelic poly(methyl methacrylate) via beta-scission (radical addition-fragmentation) chain transfer polymerisation by macromonomer chain transfer agents, as prepared by catalytic chain transfer polymerisation

alpha,omega-Dihydroxy telechelic poly(methyl methacrylate) has been prepared by beta-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 beta-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 beta-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 beta-scission chain transfer has been demonstrated to be a powerful tool in the controlled polymerisation of methacrylates by radical methodology.