Synthesis of ester-free type poly(trimethylene carbonate) derivatives bearing cycloalkyl side groups

Our ultimate goal is to create a library of ester-free type trimetylene carbonate derivatives, so that we can design and produce poly(trimethylene carbonate) (PTMC) derivatives that meet application needs. Herein we introduced cycloalkyl groups (cyclopentyl, cyclohexyl and cycloheptyl groups) into the side chain of an ester-free type PTMC. Previously, ester-free type PTMC derivatives with aromatic rings in the side chain have been reported from our group, but there have been no reports of aliphatic cyclic compounds introduced with ether linkage into their side chains. This research makes possible the production of more versatile ester-free PTMC derivatives using cycloalkyl groups. The effect of ring size was also investigated. All of the monomers gave homopolymers with Mn of a few thousands, improving the thermal degradation temperatures, compared to unmodified PTMC. We found a tendency towards increasing glass transition temperature with larger ring size.