Antibacterial piperazine‐derived quaternized copolyesters with controlled degradability

Abstract The slow degradability of aliphatic polyesters can be attributed to their poor hydrophilicity. In this article, we report on a series of biodegradable and biocompatible pH‐responsive piperazine‐based copolyesters labeled P2‐P7 synthesized by melt polycondensation approach that exhibit tunable hydrophilicity with antibacterial properties. X‐ray diffraction analysis showed the copolymers to be highly crystalline, with their crystallinity in the range of 41%–55%. Contact angle measurements showed moderate hydrophilicity, with a water contact angle of 59°–71° for P2‐P7 suggesting that the incorporation of piperazine units in the copolymer backbone moderately improves their hydrophilicity. N‐alkylation with methyl iodide further enhanced their hydrophilicity with their measured contact angles changing from 62° in unalkylated P2 to 27° in the fully alkylated analogue P12. The effect of crystallinity and hydrophilicity on polyester degradation was systematically investigated by hydrolytic degradation studies. The quaternized copolymer P10 showed ~39% reduction in molecular weight, whereas only ~19% of P2 was degraded in 8 weeks, thus exhibiting faster degradation in the quaternized polyester. The biocompatibility with U2OS cells and the antibacterial properties established their importance as potential biomedical materials.