Synthesis of biocompatible hydrophobic silica–gelatin nano-hybrid by sol–gel process

Silica–biopolymer hybrid has been synthesised using colloidal silica as the precursor for silica and gelatin as the biopolymer counterpart. The surface modification of the hybrid material has been done with methyltrimethoxysilane leading to the formation of biocompatible hydrophobic silica–gelatin hybrid. Here we are reporting hydrophobic silica–gelatin hybrid and coating precursor for the first time. The hybrid gel has been evaluated for chemical modification, thermal degradation, hydrophobicity, particle size, transparency under the UV–visible region and morphology. FTIR spectroscopy has been used to verify the presence of CH3 groups which introduce hydrophobicity to the SiO2–MTMS–gelatin hybrids. The hydrophobic property has also been tailored by varying the concentration of methyltrimethoxysilane. Contact angle by Wilhelmy plate method of transparent hydrophobic silica–gelatin coatings has been found to be as high as ∼95°. Oxidation of the organic group which induces the hydrophobic character occurs at 530 °C which indicates that the surface hydrophobicity is retained up to that temperature. Optical transmittance of SiO2–MTMS–gelatin hybrid coatings on glass substrates has been found to be close to 100% which will enable the hybrid for possible optical applications and also for preparation of transparent biocompatible hydrophobic coatings on biological substrates such as leather.