Preparation of Antimicrobial Polybutylene Succinate/Polylactic Acid Composites with a Promoting Effect on the Growth of Green Vegetables

To improve the performance of biodegradable materials and endow them with antimicrobial properties, herein, pyridine-3,5-dicarboxylic acid was introduced as a third monomer into the molecular chain of polybutylene succinate (PBS) via copolymerization, followed by introduction of pyridine quaternary ammonium into the PBS branched chain through nucleophilic substitution to afford antimicrobial PBS-BD, which was then comingled with polylactic acid (PLA) to prepare PBS-BD/PLA composites. X-ray diffraction analysis revealed that the introduction of pyridine-3,5-dicarboxylic acid caused a small shift in the diffraction peaks of PBS and a decrease in crystallinity, which was further decreased upon blending with PLA. PBS-BD and PLA were bound together by intermolecular forces. When the PBS-BD/PLA ratio was 8:2, the melting points of the two phases were the closest, the compatibility was the best, and the thermal and antimicrobial properties were optimal. The antimicrobial properties of the composites were gradually enhanced with increasing PBS-BD content, reaching optimal values for application as antimicrobial materials. The composites were degraded in soil supernatant for 6 months at a rate of 31.52%. After 42 d of enzymatic degradation, the degradation rate reached 23.24%. The PBS-BD/PLA composites promoted the growth of green vegetables to a certain extent and enhanced their nutritional value, reaching the highest chlorophyll content and vitamin C content after 45 d of growth in the presence of the composites.