Surface Interpenetrating Networks of Poly(ethylene terephthalate) and Polyamides for Effective Biocidal Properties

Poly(ethylene terephthalate) (PET) fabrics were modified by diffusing vinyl amide monomers, divinyl crosslinker N,N'-methylenebisacrylamide (MBA) and photoinitiator benzophenone (BP) into the surface of the PET substrate, which was swollen in a mutual solvent. Subsequent in situ photo-polymerization resulted in the stable entrapment of the polyamides within the surface of the PET. The PET/polyamide systems produced by this technique were physically inseparable except by melting or dissolving PET. It is referred to as a sequential interpenetrating polymer network (IPN): thermoplastic semi-IPN. Analyses of these materials by infrared spectroscopy, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) confirmed the successful incorporation of polyamide and revealed that the polyamide is also uniformly distributed along the PET yarns. Modulated differential scanning calorimetry (MDSC) indicated a certain degree of phase-mixed structure between PET and polyacrylamide, despite the thermodynamic incompatibility of two polymers, which could be induced to separate upon heating above the melting point of PET. These materials were stable upon Soxhlet extraction with distilled water for 72 h, and also with methanol for 24 more hours. After being converted to N-halamine via chlorine bleaching, these materials can bring 100% reduction of the hospital acquired methicillin-resistant Staphylococcus aureus within 10 min contact.