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Assessment of gamma-irradiated poly(ethylene oxide) based hydrogels and nanocomposites

Preparation of poly(ethylene oxide) (PEO) based hydrogels and nanocomposites by ionizing radiation may ease development of new materials with desired properties like sterile hydrogels or polyelectrolytes with enhanced conductivity. Due to its chemical nature, if PEO is irradiated dry its chains are directly affected and in the presence of oxygen it generally degrades, while in the inert atmosphere partial crosslinking is observed. in aqueous solution radiation produces reactive species in water and reaction of these species with PEO chains is supposed to lead mostly crosslinking. The degree of crystallinity of PEO can decrease both on degradation and crosslinking. We prepared and irradiated by gamma-radiation to various doses aqueous solutions of PEO with nano-silica and without it. The solutions were irradiated in presence of oxygen and in the inert atmosphere. The dried samples were investigated by a number of experimental techniques. To observe all changes corresponding to radiation effects the FTIR spectra were recorded as melt and then as films obtained by in-situ crystallization. In all samples changes were observed in vibrations characteristic of crystalline PEO at 1342 cm-1 and 1360 cm-1 that merged into a single absorption indicating amorphization. In samples irradiated in the inert atmosphere and without nano-silica changes in the shape and intensities of -C-O-C- triplet at around 1100cm-1 suggest crosslinking. On the other hand, the addition of nano-silica led to increase in intensities of -C-O-C- triplet what is more consistent degradation. The changes in selected FTIR absorptions were correlated to DSC results. The concentration of aqueous solution was significant for the outcome while the molecular mass of PEO had minor influence.

poly(ethylene oxide); gamma-irradiation; FTIR spectroscopy; hydrogels; nanocomposites

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