Reinforced soy protein isolate–based bionanocomposites with halloysite nanotubes via mussel‐inspired dopamine and polylysine codeposition

Abstract

ABSTRACTFully renewable soy protein isolate (SPI)–based film with rigid strength and sufficient water resistance is difficult to attain. In this study, the mussel‐inspired surface chemistry of ɛ‐poly‐L‐lysine (ɛ‐PL)/dopamine was exploited for codeposition onto halloysite nanotubes (HNTs) to engineer a multinetwork of HNT/SPI bionanocomposite films via physicochemical bonds. A series of ɛ‐PL/dopamine aqueous solutions at different concentration ratios were employed. The ɛ‐PL with abundant cationic amine groups could prevent the overoxidation of dopamine on HNT surfaces, thus maintaining sufficient free catechol groups for highly active reactions that improve the biphase interfacial adhesion. Moreover, HNTs surface entangled by ɛ‐PL chains could be more compatible with peptides. This codeposition of ɛ‐PL/dopamine on HNT (DLHNT) surfaces was analyzed by X‐ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, X‐ray diffraction, and thermogravimetric analysis. Compared to the control SPI film, the tensile strength of the nanocomposite film (DLHNTs0.5/SPI) was increased from 5.9 MPa to 8.25 MPa, the Young's modulus was improved by 166.4%, and the moisture absorption was reduced to 56.1% (87.2% of the control). In summary, a facile and mild bioinspired surface chemistry of ɛ‐PL/dopamine codeposition onto HNT surfaces was performed to prepare SPI‐based nanocomposite films with improved interfacial adhesion and benign compatibility. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46197.