Synthesis of antimicrobial block copolymers bearing immobilized bacteriostatic groups

Abstract

Antimicrobial block copolymers bearing covalently bonded quaternized ammonium groups were synthesized through atom transfer radical polymerization (ATRP) using hydrophobic macro-initiators based on methyl methacrylate (MMA) and tert-butyl acrylate (tBA) for further polymerization of the cationic monomer 4-vinylbenzyl dimethylhexadecylammonium chloride (VBCHAM). Subsequent hydrolysis of the tert-butyl acrylate (tBA) units led to the formation of hydrophilic acrylic acid (AA) blocks. Moreover, a new class of antimicrobial block copolymers were designed containing VBCHAM and cetyltrimethylammonium 4-styrene sulfonate (SSAmC₁₆) units, combining two types of biocide incorporation into one system, operating through both contact-based and release-based mechanisms. The bacteriostatic efficacy of the novel materials was evaluated against Gram-negative (P. aeruginosa and E. coli) and Gram-positive (S. aureus and E. faecalis) bacteria and the obtained results are compared with those of the respective random copolymers in an attempt to examine the influence of the detailed polymeric structure on the bacteriostatic properties.