In this study, a novel and convenient bio-inspired modification strategy was used to create stable superhydrophobic structures on halloysite clay nanotubes (HNTs) surfaces. The polydopamine (PDA) nanoparticles can firmly adhere on HNTs surfaces in a mail environment of pH 8.5 via the oxidative self-polymerization of dopamine and synthesize a rough nano-layer assisted with vitamin M, which provides a catechol functional platform for the secondary reaction to graft hydrophobic long-chain alkylamine for preparation of hierarchical micro/nano structures with superhydrophobic properties. The micromorphology, crystal structure, and surface chemical composition of the resultant superhydrophobic HNTs were characterized by field emission scanning electron (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The as-formed surfaces exhibited outstanding superhydrophobicity with a water contact angle (CA) of 156.3 ± 2.3°, while having little effect on the crystal structures of HNTs. Meanwhile, the resultant HNTs also showed robust stability that can conquer various harsh conditions including strong acidic/alkaline solutions, organic solvents, water boiling, ultrasonic cleaning, and outdoor solar radiation. In addition, the novel HNTs exhibited excellent packaged capabilities of phase change materials (PCMs) for practical application in thermal energy storage, which improved the mass fractions by 22.94% for stearic acid and showed good recyclability. These HNTs also exhibited good oil/water separation ability. Consequently, due to the superior merits of high efficiency, easy operation, and non-toxicity, this bionic surface modification approach may make HNTs have great potentials for extensive applications.

The biomorphic Silicon Carbide (BioSiC) ceramic with highly interconnected porous three-dimensional (3D) structure was fabricated by utilizing balsa wood cellulose nanofibers aerogel as the biotemplate and polycarbosilane (PCS) as the preceramic precursor. Evolution of morphology, composition, and pore properties from untreated wood to porous BioSiC was investigated systemically. The shrinkage and weight gain during pyrolysis was discussed. It was found that the structure of as-synthesized BioSiC was related to the microstructure of wood aerogel template and the concentration of PCS precursor. The proper microstructure of cellulose skeleton which was essential for the infiltration process could obtained by removing lignin and hemicellulose appropriately. The optimum PCS content was 40 wt. % for easy infiltration and proper SiC content. The results revealed that the dredged skeleton of cellulose was reproduced perfectly by PCS ceramization. The obtained BioSiC presented high porosity (61.03%) and low density (0.86 g/cm³) with good Darcy permeability (19.22 mD).

Fractal geometry describes the complex pore structure in natural and heat-treated wood and the relationship between pore structure and wood properties, such as strength, heat conductivity, and transport properties. However, the fractal types and the scale-dependent properties of natural and heat-treated wood remain unclear. In this study, comprehensive fractal analysis of the pore structure of natural and heat-treated spruce wood was carried out based on mercury intrusion porosimetry data. Both the volume fractal and surface fractal of natural and heat-treated wood were determined. The results showed that the two fractal types had different scale-dependent fractal properties. Four regions were identified in the pore structures. A volume fractal region was identified for pores in the region of 2–90 μm, while a surface fractal region was identified for pores in the region of 90 nm–7 μm. The pore structure in the region of 2–90 μm that corresponded to the large pore (the lumina in the cell) range showed strong volume fractal properties, and the fractal dimensions were 2.645–2.884. The pore structure in the region of 90 nm–7 μm that corresponded to the small pore (voids on or in cell walls) range showed strong surface fractal properties, and the fractal dimensions were 2.323–2.999. The range of fractal regions was hardly affected by the heat treatment atmospheres. These results showed that fractal geometry can be used to characterize the pore structures of natural and heat-treated wood. These findings are expected to explain the differences in properties between natural and heat-treated wood in the future.