Synthesis and functionalization of thiol-reactive biodegradable polymers

A novel strategy to synthesize and functionalize maleimide containing thiol reactive biodegradable polymers by the organocatalyzed (co)polymerization of a novel furan-protected maleimide-functional carbonate monomer was described. The furan-protected maleimide-containing cyclic carbonate monomer was synthesized using the protected diol. Monitoring the monomer conversion with time in the DBU catalyzed homopolymerization revealed that the polymerization became retarded at ca. 60% monomer conversion, likely a consequence of the ring-chain equilibrium associated with sterically hindered monomers. The retro Diels-Alder reaction partially occurs upon ionization by the laser. Following exposure of the furan-protected copolymers to high vacuum at 100°C, the efficiency of the rDA reaction was clearly evident from the ¹H NMR spectra of the polymers observing a complete disappearance of the resonances.