High-Performance and Fully Renewable Soy Protein Isolate-Based Film from Microcrystalline Cellulose via Bio-Inspired Poly(dopamine) Surface Modification

A novel and facile marine mussel-inspired surface modification approach for microcrystalline celluloses (MCC) and enhanced interfacial adhesion with the soy protein isolate (SPI) matrix were demonstrated in an effort to develop renewable composite films. The surface composition and micromorphology of the poly(dopamine) (PDA)-modified MCC (PDMCC) were characterized by X-ray photoelectron spectroscopy, attenuated total reflectance-Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy. The biomimetic adherent PDA layer was successfully coated onto the MCC surface via dopamine self-polymerization through a simple dip-coating method. As expected, the adlayer of PDA between the PDMCC and peptide chains greatly enhanced the mechanical properties of the resultant films. Because of the favorable interfacial adhesion between PDMCC and SPI, as certified by solid state 13C nuclear magnetic resonance and atomic force microscopy, the tensile strength of the PDMCC/SPI film was improved by 82.3%, and its water absorption was reduced by 31.3% in comparison to that of the unmodified SPI film.