Methanol crosslinking and heat-treatment methods for physical crosslinking of electrospun poly(vinyl alcohol) (PVA) nanofibres were investigated to assess their stability in water. For this purpose, PVAs with low and high molecular weights were selected. Morphology of the crosslinked membranes was characterised by scanning electron microscopy. Crystallinity of the resultant crosslinked fibres were analysed by FT-IR and differential scanning calorimetry. It has been shown that physical crosslinking increases the crystallinity of the fibres. High molecular weight PVA nanofibres showed better stability and better preservation of nanofibrous structure. Stability of the crosslinked membranes was also tested by immersion into water at room temperature and boiling water. Combined methanol and heat treatments at different temperatures and exposure periods were also investigated. Treatment at 180°C HMW PVA nanofibres for longer durations exhibited best results in terms of water stability, although it exhibited somewhat lower swelling ratios as compared to those subjected to only methanol treatment.

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Electrospun nanofibrous hydrogel membranes have been gaining significant importance due to the combination of unique physical properties of nanofibers and biocompatibility of hydrogels. Thus, they are considered as potential candidates for medical textile applications. This study deals with electrospinning of poly(vinyl alcohol) (PVA) hydrogel nanofibrous membranes. The chemical crosslinking of PVA with proportionate quantities of 1,2,3,4 butanetetracarboxylic acid (BTCA) was undertaken to form hydrogel structures. Cross-linked membranes were characterized by scanning electron microscopy, FT-IR and thermogravimetric analysis, water swelling, and durability tests. FT-IR analysis demonstrated the formation of ester linkages between PVA and BTCA and thermogravimetric analysis showed that crosslinking improved the thermal stability of the nanofibrous structure. Furthermore, the results indicated that crosslinking with BTCA improved water stability of PVA membranes and the nanofibrous structure was preserved after water treatment. It is envisaged that use of BTCA as a cross-linker to form hydrogel nanofibers could be a practical and a promising method for medical textile applications, especially for wound dressings given its nontoxicity and immiscibility with polymer solutions.

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A spirooxazine-based photochromic dye was encapsulated by an oil-in-water emulsion, solvent evaporation method. The encapsulated dye was applied to cotton fabric by a pad-cure process with different binder types. Ultraviolet (UV) protection was increased with application of the encapsulated photochromic dye. The type of binder used affected the photochromic color build-up during UV irradiation and could modify the UV protection imparted by the encapsulated photochromic dyes on textiles.