Synthesis of polymethylmethacrylate in THF solution with phosphorous containing initiators

For the synthesis of polymethylmethacrylate, tetraphenyl biphosphine (TPhBP) with a thermally and photochemically unstable P‐P bond was employed. Under the influence of UV light, this bond split to two relatively stable biphenylphosphine radicals, which are able to react with the monomer. The resultant macroinitiators were isolated and were used for further polymerization with the same or another monomer to synthesize block‐copolymers. Controlled polymerization of methyl methacrylate with tetraphenyl biphosphine took place in the absence of oxygen by UV irradiation in THF solution. For MMA alone an insignificant portion photo‐ (0.3%) and thermal‐ (2%) polymerization were detected. Using selected quantity of the initiator, macroinitiators with predicted molecular weight as well as block‐copolymers were synthesized. The macroradicals were terminated by primary ‐ PPh 2 radicals, by chain transfer to initiator and by the combination of two macroradicals. We determined chain end groups by nuclear magnetic resonance spectroscopy (NMR) and the relative molecular weights of the polymers by gel permeation chromatography (GPC). The molecular weights were calculated using the 1 H NMR spectra from the ratio between the end groups signals and signals of the chain and were compared to GPC measurements. The calculated and observed molecular weights were in good agreement. At the lower concentration of initiator the molecular weight increased with conversion, while at the higher initiator concentration the molecular weight decreased with increasing conversion which could be ascribed to chain transfer to initiator. Copyright © 2001 John Wiley & Sons, Ltd.