Repetitive sp³−sp³ Carbon−Carbon Bond-Forming Copolymerizations of Primary and Tertiary Ylides. Synthesis of Substituted Carbon Backbone Polymers:  Poly(cyclopropylidine-<i>co</i>-methylidine)

Abstract

We report a repetitive sp 3 −sp 3 carbon−carbon bond-forming polymerization for the controlled synthesis of cyclopropyl containing carbon backbone polymers with tailored end groups and molecular weight. Poly(cyclopropylidine- co -methylidine) copolymers ( 10 ) were synthesized via copolymerization of (dimethylamino)tolyloxosulfonium cyclopropylide ( 11 ) with dimethylsulfonium methylide ( 8 ). The polymer was synthesized in M n ranges from 1800 to 6714. The cyclopropyl:methyl incorporation ratios varied from 1:12 and 1:18. The composition of the poly(cyclopropylidine- co -methylidine) polymer ( 10 ) was established by NMR and IR. GPC revealed a monomodal distribution with PDI between 1.06 and 1.28. The cyclopropyl groups extend the range of functionality that can be incorporated into carbon backbone polymers and illustrate for the first time the use of tertiary ylides as monomers for the polymerization reaction. Direct control of the amount of cyclopropyl groups in the carbon backbone has potential for selective modification of the polymer by, for example, radical ring-opening reactions to create new topologies and cross-linking opportunities.