Synthesis of aliphatic polycarbonates with a tuneable thermal response

Thermally-responsive polymers have been widely studied, however access to materials in which both the thermal response can be tuned and in which the backbone is ultimately biodegradable is limited. To this end, a range of well-defined homopolymers of 2-allyloxymethyl-2-ethyltrimethylene carbonate (AOMEC) was prepared using a dual organocatalytic ring-opening polymerisation methodology. Post-polymerisation functionalisation of PAOMEC with thiols bearing a range of functional groups was optimised via photoinitated radical thiol-ene coupling reactions. The inclusion of thiol-terminated poly(ethylene glycol) (PEG) enabled the synthesis of polycarbonates that exhibit a lower critical solution temperature (LCST). This approach enables the facile modification of the cloud point of these materials to create a library of thermally-responsive polymers, achieved by simply varying the molecular weight of the PEG chains and grafting blends of PEG to PAOMEC.