Surface characterization and antibacterial activity of chitosan-grafted poly(ethylene terephthalate) prepared by plasma glow discharge

Poly(ethylene terephthalate) (PET) texture was exposed to oxygen plasma glow discharge to produce peroxides on its surfaces. These peroxides were then used as catalysts for the polymerization of acrylic acid (AA) in order to prepare a PET introduced by a carboxylic acid group (PET‐A). Chitosan and quaternized chitosan (QC) were then coupled with the carboxyl groups on the PET‐A to obtain chitosan‐grafted PET (PET‐A‐C) and QC‐grafted PET (PET‐A‐QC), respectively. These surface‐modified PETs were characterized by attenuated total reflection Fourier transform IR spectroscopy, electron spectroscopy for chemical analysis, and a contact angle goniometer. The amounts of AA, chitosan, and QC grafted on the PET surfaces as determined by the gravimetric method were about 6, 8, and 9 μg/cm2, respectively. The antibacterial activity of the surface‐modified PET textures was investigated using a shake flask method. After 6 h of shaking, the growth of bacteria was markedly inhibited by PET with ionically (86% in PET‐A−‐C+) and covalently (75% in PET‐A‐C) grafted chitosan and with covalently grafted QC (83% in PET‐A‐QC). After the laundering the inhibition of the growth of the bacteria was maintained in the range of 48–58%, showing the fastness of the chitosan‐grafted PET textures against laundering. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2769–2778, 2001