Synthesis and characterization of amphiphilic poly(urethaneurea)-comb-polyisobutylene copolymers

In this paper we describe the synthesis and characterization of modified polyurethaneurea-polyether (PEUU) multiblock copolymers, designed to elicit lower permeability to water vapor and gases. The approach was to create polyisobutylene (PIB) segments, which were linked to the PEUU copolymer as combs. Macromonomers of PIB were synthesized, containing two hydroxyl sites on the initiating ends of the molecules for subsequent condensation polymerization. By using a polymerization scheme that offered no termination and no chain transfer, the PIB macromonomer would be assured of having two (and only two) hydroxyl groups. Characterization of the macromonomers and their precursors was performed by GPC, ¹H NMR, and FTIR. Using these products, amphiphilic copolymers, with a polyurethaneurea-polyether multiblock backbone and polyisobutylene combs, were synthesized by a condensation reaction. PIB incorporation varied between about 2 and 30%, with comb lengths ranging from approx. 3000 to 29,000 g/mol. Characterization of this new multiblock multicomb copolymer was performed by GPC, FTIR, solid state ¹³C NMR, and Soxhlet extraction techniques.