The recyclable, shape-memory, and self-healing soy oil-based polyurethane (S-PU) networks were constructed by the thermoreversible Diels-Alder (DA) reaction between S-PU (sealed with furfuryl alcohol) and 1,5-bis(maleimido)-2-methylpentane. The DA and retro-DA reactions between furan and maleimide were investigated by Fourier transform infrared spectroscopy, differential scanning calorimetry, solubility, and recycle testing. Moreover, the shape-memory properties of the S-PU networks were studied by qualitative recovery testing and quantitative cyclic tensile testing. Furthermore, the self-healing properties of S-PU networks were confirmed by cut, scratch, and tensile testing. The results showed that, compared to the traditional S-PU, the novel S-PU prepared in this work was recyclable and self-healing. And although both of them have shape-memory effect, the novel S-PU has a higher shape fixed rate and shape recovered rate than the traditional S-PU.

We report the finding of a photochromic phenomenon from a structural epoxy resin, which also has pH-, thermal-, solvent-, and mechanical-response property. Through designing model compounds and doing confirmatory experiments, we find out that one kind of diarylmethane dye (Michler's hydrol blue) is the chromogen of this epoxy resin. Additionally, we propose and successfully verify the mechanism of this novel color-change phenomenon that it is an oxidation-heterolysis mechanism. Further, the Fourier transform infrared (FTIR) spectroscopy and gel permeation chromatography (GPC) data show that the chromogen can be used as a photoinitiator to initiate free radical polymerization. Additionally, the discovery process is inspiring, which can lead to many applications.

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A series of wholly soy-based semi-interpenetrating polymer networks (semi-IPN) have been successfully prepared from soy–oil–polyol-based polyurethane (S-PU) and modified soy protein isolate (M-SPI). Morphology, structure and miscibility of the semi-IPN films have been investigated by Fourier transform infrared (FT-IR) spectroscopy, film density, scanning electron microscopy (SEM), wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), and ultraviolet–visible (UV–vis) spectroscopy. The results show that the hydrogen bonds existing between S-PU chains are partially destroyed during the loading of M-SPI. In addition, the measured density of semi-IPN films are higher than the theoretically values, indicating the penetration of M-SPI into S-PU networks to bind intimately. Good miscibility between S-PU and M-SPI is confirmed by the single T g observed in DSC and the high light transmittance under low M-SPI content (<20 wt %). Furthermore, DSC and DMTA results reveal that phase separation between S-PU and M-SPI in the films occurred when M-SPI content ranges from 20 to 80 wt %. After extraction of the M-SPI with tetrahydrofuran from semi-IPN, the morphology, structure and domain size of the films could be clearly observed by SEM. The mechanical properties of the semi-IPN films are investigated by tensile testing. The tensile strength of the films enhances from 7.5 to 31 MPa, while the breaking elongation recedes from 228% to 20% with the increase of M-SPI content from 0 to 80 wt %.

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