Chitosan–silica hybrid porous membranes

• Hybrid membranes prepared by sol–gel reactions inside the pores of chitosan scaffolds.
• Chitosan was crosslinked by genipin with the optimal method and concentration.
• Silica phase is co-continuous with chitosan in the final porous hybrid.
• Increase of Young’s modulus up to two orders of magnitude for water swollen hybrids.
• Adjusting the silica precursors ratio allows the modulation of the hybrid properties

Chitosan–silica porous hybrids were prepared by a novel strategy in order to improve the mechanical properties of chitosan (CHT) in the hydrogel state. The inorganic silica phase was introduced by sol–gel reactions in acidic medium inside the pores of already prepared porous scaffolds. In order to make the scaffolds insoluble in acidic media chitosan was cross-linked by genipin (GEN) with an optimum GEN concentration of 3.2 wt.%. Sol–gel reactions took place with Tetraethylorthosilicate (TEOS) and 3-glycidoxypropyltrimethoxysilane (GPTMS) acting as silica precursors. GPTMS served also as a coupling agent between the free amino groups of chitosan and the silica network. The morphology study of the composite revealed that the silica phase appears as a layer covering the chitosan membrane pore walls. The mechanical properties of the hybrids were characterized by means of compressive stress–strain measurements. By immersion in water the hybrids exhibit an increase in elastic modulus up to two orders of magnitude.

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