Methacrylate-based shape manipulable wood with catalyst-free dynamic hemiacetal ester networks

Abstract

The insufficient structural design and unfriendly preparation have greatly limited the development of thermal-induced shape memory materials. A methyl methacrylate (MMA)-based shape manipulable wood composite (SMW) is fabricated by integrating the catalyst-free hemiacetal ester networks with hierarchical anisotropic wood skeleton based on free radical in-situ polymerization and cross-linking reaction. In the as-obtained SMW, hierarchical wood framework (WF) and high-strength MMA act as mechanical skeleton and polymer network backbone, respectively, while methacrylic acid (MAA) promotes dynamic cross-linkage. The SMW possesses satisfactory comprehensive performances including desirable preparation efficiency, ideal optical property, anisotropic light-guiding effect, low thermal conductivity (≈0.22 W m−1 K−1), satisfactory UV shielding effect and benign mechanical performances (longitudinal tensile strength of 34.54 MPa and flexural strength of 53.64 MPa). The catalyst-free dynamic exchange reaction combined with hierarchical wood skeleton endows the obtained SMW with shape memorability and manipulability, and the shape can be manipulated on demand without environmental-burden catalyst, which facilitates the industrial exploration, add-value development, and intelligent application of wood-based materials.