Multiple crosslinking bionanocomposites reinforced with mussel‐inspired poly(dopamine) surface modified nanoclay: Construction, properties, and characterization

This article reports a bioinspired strategy for the preparation of robust soy protein isolate (SPI) based nanocomposites using a poly(dopamine) coating montmorillonite (D‐MMT) as reinforcement and ferric ion (Fe^(III)) as a coordination crosslinking center. Typically, the catechol groups present on MMT provide multiple crosslinking reaction sites for bio‐nanocomposites reinforcement: Coordination among Fe^(III)‐catechol interactions as well as covalent interactions based on the Michael addition/Schiff base reaction or hydrogen‐bonded between D‐MMT and the SPI matrix. The morphological, mechanical, hydrophobic, water‐resistant, and thermal behaviors of the resultant SPI‐based nanocomposites were investigated. The interaction between D‐MMT and the SPI matrix was investigated via the scanning electron microscopy and atomic force microscopy. The results showed that, with 5 wt% D‐MMT loading, the tensile strength, and elasticity modulus of the SPI‐based nanocomposite films increased by 75.2 and 135.2%, respectively, compared with the control. The enhanced mechanical properties of the obtained modified films were, in fact, a result of the multiple crosslinking system, as confirmed by the Fourier transform infrared spectroscopy and solid‐state ¹³C CP/MAS NMR spectroscopy. The bionanocomposite films also demonstrated reduced water absorption and water solubility, and enhanced thermal stability performance compared to the other film samples. POLYM. COMPOS., 39:E90–E100, 2018. © 2017 Society of Plastics Engineers