Biofilms from soy protein isolate and polyfurfuryl alcohol

Developing biofilms with low water uptake could be a promising route to potential environmentally friendly applications. Here, we describe an environmentally friendly approach to physically adsorb water-insoluble polyfurfuryl alcohol (PFA) on soy protein isolate (SPI) to develop a new material. Adsorption of PFA on SPI is confirmed from solid state NMR spectroscopy with the decrease in the –CH₂OH peak around 57 ppm. These types of biofilms are derived from 100% renewable resources. The mechanical performance of these biofilms (at 65±2% RH) cured at optimum curing time showed a mechanical strength, σ, of ∼20 MPa, a Young's modulus, E, of ∼0·5 GPa, and a maximum water uptake of ∼50% when immersed fully in water for 24 h with good dimensional stability. Additionally, thermal stability of the biofilms increased with the adsorption of PFA on SPI. Surface morphology showed the presence of physically adsorbed PFA on the surface of SPI.