Polymerization of 1-(Trimethylstannyl)alkyl Methacrylates: A New Class of Organotin Polymers and a Novel Case of Degradative Chain Transfer to Polymer

Abstract

The synthesis of poly[1-(trimethylstannyl)alkyl methacrylates], a new class of organotin polymers, is reported. The trimethyltin group is substituted on C-1 of the ester side chain, differing from conventional stannyl methacrylates where the tin is bonded directly to oxygen. The monomer synthesis was carried out by condensation of lithium trimethylstannate with a carbonyl compound, followed by esterification with methacryloyl chloride. Both homopolymers and MMA copolymers were prepared by radical polymerization. A reactivity ratio study showed copolymerization was perfectly random. A novel degradative chain transfer to polymer process was observed in the polymerization of monomers containing a secondary or benzylic hydrogen a to the trimethyltin group. The proposed mechanism involves a 5-membered cyclic transition state. The effect was most dramatic with tin substituted on a benzyl side chain, and the deuterium isotope effect for the polymerization of this monomer was determined to be 2.4. The effect of the trimethyltin group on the glass transition temperatures and the thermal stability of these materials is reported. © 1987, American Chemical Society. All rights reserved.