Facile synthesis of 1,4-cis-polyisoprene–polypeptide hybrids with different architectures

Abstract

The synthesis of polypeptide hybrids by controlled/living ring-opening polymerization of N-carboxyanhydrides (NCA) using Schreiner's thiourea catalyst and amino-alcohol terminated poly(1,4-cis-isoprene)s as initiators was demonstrated for γ-benzyl-L-glutamate (BLG) and ε-tert-butyloxycarbonyl-L-lysine (BLL) NCAs. One-pot synthesis of amino-alcohol terminated macroinitiators from heterotelechelic keto/aldehyde polyisoprene by reductive amination of carbonyl(s) was presented. Selection of amines allowed to obtain mono-, di- and tri-functional macroinitiators that were used for the synthesis of polyisoprene–polypeptide hybrids of different architecture: AB, BAB, AB₂, BAB₂, CBABC. Due to the living character of the polymerization, the molar mass of the polypeptide blocks could be controlled by the monomer to initiator ratio (6000 < M_n < 44 000 g mol⁻¹), while sequential monomer addition allowed the synthesis of a pentablock terpolymer: poly(BLG-b-BLL-b-isoprene-b-BLL-b-BLG).