ANTIMICROBIAL COPOLYMERS FROM PARA-AMINOPYRIDINE METHACRYLATE AND METHYL METHACRYLATE: SYNTHESIS AND STRUCTURE–PROPERTY RELATIONSHIPS

Functional copolymers based on para-aminopyridine methacrylate (p-APM) and methyl methacrylate (MMA) were synthesized via radical polymerization in benzene at 60 °C using azobisisobutyronitrile as the initiator. The copolymerization parameters determined by the Fineman–Ross method (r₁ = 0.85 ± 0.04, r₂ = 0.45 ± 0.03) indicated a higher reactivity of p-APM, resulting in copolymers enriched in aminopyridine units. IR and ¹H NMR analyses confirmed that polymerization proceeds through the vinyl groups with complete retention of amino and pyridine functionalities in the side chains. Thermogravimetric analysis revealed high thermal stability up to 380 °C, exceeding that of polymethyl methacrylate. Mechanical tests showed enhanced strength (91–95 MPa) and Vica softening temperatures of 148–152 °C, surpassing commercial Plexigum M-272. Antimicrobial activity, evaluated by the agar diffusion method, demonstrated pronounced inhibitory effects against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) strains. Copolymers containing 89.2 mol% p-APM exhibited the highest antimicrobial efficiency, while moderate activity was observed at lower functional-monomer ratios. The biocidal efficiency correlated with both the content and distribution of p-APM units along the polymer chain. The combination of high thermal stability, mechanical strength, and antimicrobial activity suggests that p-APM–MMA copolymers are promising materials for biomedical coatings, membranes, and polymer systems with controlled antimicrobial properties.