Phosphorus-Containing Block Copolymers from the Sequential Living Anionic Copolymerization of a Phosphaalkene with Methyl Methacrylate.

Abstract

Although living polymerization methods are widely applicable to organic monomers, their application to inorganic monomers is rare. For the first time, we show that the living poly(methylenephosphine) (PMPn - ) anion can function as a macroinitiator for olefins. Specifically, the phosphaalkene, MesP=CPh2 (PA), and methyl methacrylate (MMA) can be sequentially copolymerized using the BnLi-TMEDA initiator system in toluene. A series of PMPn -b-PMMAm copolymers with narrow dispersities are accessible (Đ=1.05-1.10). Analysis of the block copolymers provided evidence for -P-CPh2 -CH2 -CMe(CO2 Me)- switching groups. Importantly, this indicates that the -P-CPh2 - anion directly initiates the anionic polymerization of MMA and stands in stark contrast to the isomerization mechanism followed for the homopolymerization of PA. For the first time, the glass transition of a PMPn homopolymer has been measured (Tg =45.1 °C, n=20). The PMPn -b-PMMAm copolymers do not phase separate and show a single Tg which increases with higher PMMA content.