Regioregular Polymers from Biobased (R)-1,3-Butylene Carbonate

We present (R)-1,3-butylene carbonate (R-BC) as a biorenewable monomer for the preparation of semicrystalline aliphatic polycarbonates. This conversion is achieved by using enantiomerically pure, biobased (R)-(-)-1,3-butanediol (bio-BG) as a renewable feedstock. Ring-opening polymerization from select catalysts at low temperatures can yield regioregular poly((R)-1,3-butylene carbonate) (R-PBC) with semicrystalline properties (X-reg = > 0.99; T-m = 72 degrees C). Along with the R-enantiomeric polymer, the alternate stereochemical polymers (using S- and racemic BC) were investigated. Our analysis shows that the highest level of crystallinity is achieved with regioregular, biobased R-PBC compared to the petrol-based S- and racemic congeners. This work shows the potential of stereochemically pure bio-BG as a starting material for semicrystalline, aliphatic carbonates when high regioregularity is achieved in the polymer microstructure. The synthesis and thermal characterization of regioregular butylene carbonate polymers are described in detail.