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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. 

Here, we report the closure resistance of a soft-material bilayer orifice increases against external pressure, along with ruga-phase evolution, in contrast to the conventional predictions of the matrix-free cylindrical-shell buckling pressure. Experiments demonstrate that the generic soft-material orifice creases in a threefold symmetry at a limit-load pressure of p / μ  ≈ 1.20, where μ is the shear modulus. Once the creasing initiates, the triple crease wings gradually grow as the pressure increases until the orifice completely closes at p / μ  ≈ 3.0. By contrast, a stiff-surface bilayer orifice initially wrinkles with a multifold symmetry mode and subsequently develops ruga-phase evolution, progressively reducing the orifice cross-sectional area as pressure increases. The buckling-initiation mode is determined by the layer's thickness and stiffness, and the pressure by two types of the layer's instability modes—the surface-layer-wrinkling mode for a compliant and the ring-buckling mode for a stiff layer. The ring-buckling mode tends to set the twofold symmetry for the entire post-buckling closure process, while the high-frequency surface-layer-wrinkling mode evolves with successive symmetry breaking to a final closure configuration of two- or threefold symmetry. Finally, we found that the threefold symmetry mode for the entire closure process provides the orifice's strongest closure resistance, and human saphenous veins remarkably follow this threefold symmetry ruga evolution pathway. 

Abstract We report closed-form formulas to calculate the incremental-deposition stress, the elastic relaxation stress, and the residual stress in a finite-thickness film from a wafer-curvature measurement. The calculation shows how the incremental deposition of a new stressed layer to the film affects the amount of the film/wafer curvature and the stress state of the previously deposited layers. The formulas allow the incremental-deposition stress and the elastic relaxation to be correctly calculated from the slope of the measured curvature versus thickness for arbitrary thicknesses and biaxial moduli of the film and the substrate. Subtraction of the cumulative elastic relaxation from the incremental-deposition stress history results in the residual stress left in the film after the whole deposition process. The validities of the formulas are confirmed by curvature measurements of electrodeposited Ni films on substrates with different thicknesses.