Facile Fabrication of Chitosan/Starch Composite Films with Fumed Silica as an Additive

Abstract

Chitosan/cassava starch (CS/ST) composite films with different CS:ST (w/w) ratios were prepared by solution casting and investigated as a support for fumed silica (fSiO₂) dispersion. The CS, as a 1% (w/v) solution in 1% (w/v) acetic acid, and gelatinized ST, as a 3% (w/v) solution in 1% (w/v) acetic acid, were mixed at the appropriate volume ratios with a homogenizer, and then fSiO₂ at 1, 3, or 5% (w/w of CS) was added and cast as films. The morphology, tensile strength, contact angle, X-ray diffraction (XRD) pattern, and surface functional groups of the films were investigated. The external morphology of the CS/ST composite film revealed that the fSiO₂ particles were homogeneously dispersed into the polymer matrix. The water absorption and surface hydrophobicity of the composite film increased with increasing ST or CS contents. The hydrophobic acetyl groups of CS caused a notable reduction in the wettability as well as the water adsorption ability, which are preferable for a packaging film application. The CS/ST film with a high fSiO₂ content had a higher tensile strength due to the reinforcement effect of the fSiO₂ nanoparticles. The XRD patterns of the CS/ST films revealed that the 2q of the crystalline region of CS were slightly changed when including the fSiO₂. The shift in the ST diffraction peak was probably due to the change in its chain orientation caused by hydrogen-bonding interactions between CS and ST molecules, resulting in their good adhesion.