Chemical modification of poly(isosorbide carbonate)-based copolymers with boronic acids and the ammonolysis of the modified copolymers

Abstract

Here, the functionalization of bio-based polycarbonates by post-polymerization modification with boronic acids was demonstrated as an effective method for tuning the thermal and physical properties of original polymers without losing their original nature, i.e., the degradability into monomers and urea by ammonolysis. Poly(isosorbide carbonate)-based copolymers with hydroxy groups in the polymer main chain were modified using boronic acids. The boronic acids used as modifiers were categorized into 1) low-molecular-weight boronic acids and 2) polymers-containing boronic acids. These modifications clearly affected the thermal and mechanical properties of the polymer. Further, the construction of boronic esters between hydroxy groups in poly(isosorbide carbonate)-based copolymer and modifiers with two or more boronic acids noticeably varied the mobility of the main chain and yielded the cross-linked structure. The modified polymers, including the cross-linked one, were successfully decomposed into monomers and urea by the treatment with aqueous ammonia. Thus, this study demonstrates a design guideline that balances the stability of the materials and their degradability after use.