Structural and mechanical properties of a range of chitosan-based hybrid networks loaded with colloidal silica and polystyrene particles

We have prepared a range of chitosan-based interpenetrating network (IPN) materials in thin film form and analyzed these with respect to their mechanical and structural properties. The structures were analyzed before and after modification with a tetraethylorthosilicate (TEOS) cross-linker and various-sized silica and polystyrene particles—which were added to determine the influence of such particles on the mechanical properties of the resulting IPNs. The method of incorporation of particles was also investigated. All films were prepared by drop casting with experimental conditions such as temperature, substrate and time kept constant throughout. Results from the mechanical tests show a decrease in flexibility of the chitosan network upon cross-linking with TEOS. However, a significant increase in the tensile strength was observed when the TEOS-modified chitosan network was combined with colloidal silica and polystyrene particles; interestingly, this increase in tensile strength appears to correlate with increasing surface area of the particles, suggestive of a further cross-linking action. Results from the structural analysis show that there was little or no change to the chitosan chain network after cross-linking; this suggests that upon cross-linking a weakly bonded IPN is being formed which may then be further modified by the inclusion of the particles studied. These findings are discussed in terms of the potential use of such hybrid materials as wound dressings or drug-release patches.