Synthesis and Applications of Novel Antimicrobial Polymeric Materials

Abstract

Antimicrobial precursors, especially N-halamine precursors, were developed and synthesized. After being applied onto polymers and fibers, the durability, rechargeability and antibacterial efficacy of the N-halamine-treated polymers and fibers were evaluated. An s-triazine-based reactive group was synthesized and used for attaching N-halamine precursor onto cotton fabrics, and crosslinking agents were employed for antimicrobial finishing. An antimicrobial acrylic fiber and m-aramid/cellulose composite fiber were invented and prepared using the dry-jet wet spinning process, and physical properties, as well as antimicrobial efficacy, were investigated. After synthesizing and characterizing an s-triazine-based N-halamine precursor, dichloro-m-aminophenylhydantoinyl-s-triazine (DAPHT), this was applied to cotton fabrics through a reactive dyeing process. The optimum condition through the dyeing process was investigated. Due to the lower dyeing temperature (~30ºC), the application allows mild processing conditions. Since even after 50 standard-washing cycles the recharged chlorine-recovery was over 60%, the durability of the material is sufficient for practical application. Bacterial efficacy tests resulted in inactivation of both Gram-positive and Gram-negative bacteria within 30 min with 6 log reductions. To apply m-aminophenyl hydantoin (MAPH) onto cotton fabric, polycarboxylic acids provided good connection between MAPH and cotton cellulose. Through one finishing process, the MAPH treated cotton fabrics have durable press properties as well as antimicrobial activities. The chlorinated BTCA/MAPH treated cotton fabric provided inactivation against Gram-positive and Gram-negative bacteria within 1 min of contact time. An antimicrobial-acrylic fiber precursor (PAN/PSH composite fiber) was produced by dry-jet wet spinning. The acrylic fiber possessed durable and rechargeable antimicrobial properties up to 50 standard washing cycles, and the chlorinated acrylic fibers inactivated S. aureus (Gram-positive bacteria) within 30 min. Cellulose and m-aramid were dissolved in an ionic liquid, and dry-jet wet spinning was used to prepare composite fibers which could be rendered antimicrobial through exposure to chlorine bleach. Chlorination of the aramid nitrogen produced antimicrobial properties which were retained over 50 standard-washing cycles. Cellulose/m-aramid blends showed a much higher chlorination level than the pure m-aramid fiber. Up to 10% (based on the weight of cellulose) m-aramid composite fibers did not produce any decrease in mechanical properties. The chlorinated fibers inactivated both E. coli O157:H7 (Gram-negative bacteria) and S. aureus (Gram-positive bacteria) within 5 min with 6 log reductions. As medical textiles and biomaterials for healthcare, N-halamine treated polymers and fibers have potential for commercial use and through this research, novel and variable applications are suggested.