Benzyl chloride-functionalized polycarbonates: A versatile platform for the synthesis of functional biodegradable polycarbonates

Abstract

An aliphatic polycarbonate containing pendant benzyl chloride groups was synthesized by organocatalytic ring-opening polymerization (ROP) of a cyclic carbonate monomer (MTC-OCH2BnCl). Facile postpolymerization modification of the resultant polymer with various nucleophiles facilitated access to a functionally diverse variety of polycarbonate materials in high yield, including those that contained diethanolamine, phosphonium, and azide groups. The azide-functionalized polycarbonates could be further elaborated via Cu-catalyzed click chemistry with alkynyl-functionalized poly(ethylene glycol) (PEG) or pyrene to form the corresponding PEG- or pyrene-grafted polymers. Finally, an amphiphilic block copolymer containing grafted pyrene units in the hydrophobic block was synthesized using the aforementioned postpolymerization click functionalization strategy. We show by transmission electron microscopy (TEM) and light scattering that the block copolymer self-assembles into micelles of 48 nm diameter in aqueous media and that the critical micelle concentration (CMC) of the nanoparticles was lower than that exhibited by similarly sized micelles formed from a control block copolymer containing no pyrene (CMC values of 6.3 and 8.1 mg L-1, respectively).