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Abstract: This paper reports interesting differences between physical and mechanical properties of various membranes prepared from high and low molecular weight poly (vinyl alcohol) (PVA) and xanthan gum (XG) blends irradiated under low dose electron beam. The membranes were designed for sustained delivery of diltiazem hydrochloride through skin. Electron beam irradiation produced crosslinks and turned PVA into crystalline phase from its amorphous organization in the unirradiated state. PVA crystals were fibrillar at low XG content (1wt.%) when the molecular weight was high while similar orientation at higher XG content (5wt.%) when the molecular weight was low. Low molecular weight PVA–XG membranes showed equivalent physical properties under dry condition but wet-mechanical properties were superior for high molecular weight PVA–XG hybrids. Both of them showed slow and sustained diltiazem release but the later induced slightly slower release despite low drug encapsulation efficiency due to its better wet mechanical strength. [Copyright &y& Elsevier]

Aqueous nanosilica sol (particle size range: 9-13 nm, pH: 9.0) was added at various low concentration range (0.5-2 wt.%) into aqueous poly (vinyl alcohol) (PVA) of different molecular weight (98% hydrolyzed, 20 wt.%) (pH: 5.0) at room temperature under constant stirring to synthesize organic-inorganic hybrid hydrogels in presence of sodium lauryl sulphate as a silica dispersant. Buffer tablets were added to arrest the pH at 9.0 (to prevent any silica aggregation due to change in pH). The resultant hybrids were cast on Teflon sheets and dried in an oven at 50°C to drive out all the unbound water. Those films were then subjected to freese-thaw treatment continuously for 5 h. The freese-thawed films appeared opaque. The swelling-de swelling experiments with the hydrogels were carried out in distilled water at room temperature and consequently allowed to de-swell naturally. Those observations were correlated with the microstructures of the hybrid hydrogels. [ABSTRACT FROM AUTHOR]