Antibacterial poly（D,L-lactide） （PDLLA） fibrous membranes were developed via electrospinning, followed by surface modification which involved plasma pretreatment, UV-induced graft copolymerization of 4-vinylpyridine （4VP） and quaternization of the grafted pyridine groups with hexylbromide. The success of modification with quaternized pyridinium groups on the PDLLA fibrous membranes was ascertained by X-ray photoelectron spectroscopy （XPS）. The antibacterial activities of these membranes were assessed against Gram-positive Staphylococcus aureus （S. aureus） and Gram-negative Escherichia coli （E. coli）. The PDLLA fibrous membranes modified with quatemized pyridinium groups showed antibacterial efficiency against both bacteria as high as 99.999%. The results demonstrated that the antibacterial activity was based on the interaction of the positive charge of pyridinium group and negatively charged cell membrane of bacteria, resulting in loss of membrane permeability and cell leakage.
The interpenetrating polymer network(IPN) silicone hydrogels with improved oxygen permeability and mechanical strength were prepared by UV-initiated polymerization of monomers including methacryloxypropyl tris(trimethylsiloxy)silane(TRIS),2-hydroxyethylmethacrylate(HEMA) and N-vinyl pyrrolidone(NVP) in the presence of free radical photoinitiator and cationic photoinitiator.The polymerization mechanism was investigated by the formation of gel network.The structure of IPN hydrogels was characterized by Fourier transform infrared spectroscopy(FTIR), differential scanning calorimetry(DSC) and transmission electron microscopy(TEM).The results showed that the IPN hydrogels exhibited a heterogeneous morphology.The mechanical properties,surface wettability and oxygen permeability were examined by using a tensile tester,a contact angle goniometer and an oxygen transmission tester,respectively.The equilibrium water content of the hydrogels was measured by the gravimetric method.The results revealed that the IPN hydrogels possessed hydrophilic surface and high water content.They exhibited improved oxygen permeability and mechanical strength because of the incorporation of TRIS.
Zein/chitosan composite fibrous membranes were fabricated from aqueous ethanol solutions by electrospinning. Poly（vinyl pyrrolidone） （PVP） was introduced to facilitate the electrospinning process of zein/chitosan composites. The asspun zein/chitosan/PVP composite fibrous membranes were characterized by scanning electron microscopy （SEM） and tensile tests. SEM images indicated that increasing zein and PVP concentrations led to an increase in average diameters of the composite fibers. In order to improve stability in wet stage and mechanical properties, the composite fibrous membranes were crosslinked by hexamethylene diisocyanate （HDI）. The crosslinked composite fibrous membranes showed slight morphological change after immersion in water for 24 h. Mechanical tests revealed that tensile strength and elongation at break of the composite fibrous membranes were increased after crosslinking, whereas Young＇s modulus was decreased.
