Abstract
Sustainable alternatives to petroleum-based plastics are needed urgently, but biodegradable materials from renewable sources often suffer from inadequate mechanical properties. Here, we demonstrate a bio-inspired strategy to enhance soy protein isolate (SPI) nanocomposites through surface modification of cellulose nanocrystal (CNC) reinforcing filler particles with a polydopamine (polyDOPA) coating via dopamine polymerization under alkaline conditions. This modification creates multifunctional interfaces at filler surfaces that enhance nanocomposite mechanical properties likely by simultaneously altering filler dispersion and filler–matrix interactions. PolyDOPA-modified CNCs increase the tensile strength and elastic modulus of SPI films (plasticized with 50% glycerol) by more than threefold compared to unreinforced controls. Transmission electron microscopy, spectroscopic techniques, and thermal analysis reveal that polyDOPA coatings influenced nanocomposite structure across multiple length scales, tripling the effective diameter of the CNC inclusions, reducing the tendency of CNC nanocrystals to aggregate, and increasing the glass transition temperature. The increase in glass transition temperature suggests reduced SPI molecular mobility, which, along with micromechanical modeling, indicates the potential for improved interfacial interactions. Results reveal how polyDOPA-modified CNCs influence the interphase behavior and filler dispersion of SPI-glycerol nanocomposites, providing a pathway to further improve their performance for various applications, including packaging, membranes, and coatings.
| Original language | English |
|---|---|
| Journal | Polymer Composites |
| DOIs | |
| State | Accepted/In press - 2025 |
Funding
This work was supported by the National Science Foundation (DMR 2105150, CMMI 1548571, and OIA 2219142), Center for Structural Molecular Biology (CSMB) (FWP ERKP291), Office of Biological and Environmental Research, U.S. Department of Energy. Funding: This work was supported by the National Science Foundation through awards DMR 2105150, CMMI 1548571, and OIA 2219142, and by the molecular microbiology imaging facility at Washington University in St. Louis and the TEM core of The State University of New York Upstate Medical University. A portion of this work was supported under the funding to the Center for Structural Molecular Biology (CSMB) under Contract FWP ERKP291, Office of Biological and Environmental Research, U.S. Department of Energy. We acknowledge the use of the chemical and environmental analysis facility at Washington University in St. Louis and the helium pycnometry facility of the materials research institute at The Pennsylvania State University. We also acknowledge the utilization of artificial intelligence to refine the language of this paper, which was carefully reviewed and revised to reflect the authors' own interpretations and perspectives.
Keywords
- cellulose nanocrystal
- nanocomposite
- protein-based material