Starch/poly (butylene adipate-co-terephthalate) blown films contained the quaternary ammonium salts with different N-alkyl chain lengths as antimicrobials

Abstract

Antimicrobial biodegradable packaging is in high demand as a one-two punch against microbiological and plastic hazards. Two quaternary ammonium salts (QAS) with different N-alkyl chain lengths were used for starch/poly (butylene adipate-co-terephthalate) (PBAT) blown antimicrobial films. Dioctadecyl dimethyl ammonium chloride (D1821) contributed to a homogeneous film morphology at 5% w/w level, while micro-pores occurred with didodecyl dimethyl ammonium chloride (D1221). Increasing QAS content weakened hydrogen bonding interactions. D1821 promoted the formation of intercalated structure of nano-clays, and improved the strength, thermal stability, barrier, and surface hydrophobicity of the films. Conversely, adding D1221 decreased the mechanical properties, and significantly enhanced the surface hydrophilicity. The films with 3% and 5% w/w D1221 obviously inhibited the growth of both Staphylococcus aureus and Escherichia coli, while those with D1821 cannot show clear zone against the Gram-negative. 5% w/w D1221-loaded film delayed the growth of microorganisms in beef, of which the total viable count was 5.75 lg CFU/g after 21-day chilling storage. Findings supported that QAS had the potential for manufacturing starch/PBAT antimicrobial packaging, but the release kinetics and cytotoxicity still need to be systematically explored before application.