Synthesis and Antimicrobial Activity of Poly (ethylene-co-acrylic acid) (PEAA) with Quaternary Ammonium Salts

Abstract

To improve the antimicrobial performance of Poly (ethylene-co-acrylic acid) (PEAA) copolymer, a PEAA copolymer was modified by an alkyl quaternary ammonium salt (QAS) via Steglich esterification using N, N'-dicyclohexylcarbodiimide (DCC) as a catalyst. The modified polymers with dodecyl dimethyl hydroxyethyl ammonium chloride (DDHAC), which was synthesized by quaternization of dimethylethanolamine (DMEA) with 1-chlorododecane, were effective for inhibiting the growth of microorganisms due to their hydrophobic chains bonded to PEAA copolymers. The results suggest that a PEAD135 polymer which was reacted at 135 ºC showed the highest antibacterial activity against Gram-positive bacteria Staphylococcus aureus and Gram-negative bacteria Escherichia coli. However, PEAD165, PEAD175, and PEAD185 showed much lower antibacterial activity, compared to that of PEAD135. This is because the low conversion of DDHAC was observed as the increase of temperature above 165 ºC, causing reduction of antibacterial activity. As a result, the antibacterial activity was affected by the degree of surface modification of DDHAC according to their reaction temperature. A PEAD135 polymer synthesized in this study could be applied to the microfiber mats through an electrospinning technique, showing in a 99.9% reduction by antibacterial evaluation.