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Abstract:In this paper, water-soluble 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cellulose with a high degree of oxidation was prepared by a two-step process using bamboo dissolving pulp. The first step was to destroy the cellulose crystal I by NaOH/urea solution to obtain cellulose powder with decreased crystallinity. The second step was to oxidize the cellulose powder by TEMPO oxidation. The TEMPO-oxidized cellulose was analyzed by Fourier transform infrared spectroscopy (FTIR), conductimetry, X-ray diffraction (XRD), fiber analyzer, and transmission electron microscopy (TEM). FTIR showed that the hydroxymethyl groups in cellulose chains were converted into carboxyl groups. The degree of oxidation measured by conductimetry titration was as high as 91.0%. The TEMPO-oxidized cellulose was soluble in water for valuable polyelectrolytes and intermediates.

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Wood is a natural, abundant, renewable resource, which is easily processed, has beautiful texture and good mechanical strength, and is widely used for furniture, flooring, decor and building construction. However, wood is vulnerable to moisture and microorganisms, resulting in deformation, cracks, mold and degradation, which causes aesthetic problems and/or shortens the service life of wood products. In this paper, superhydrophobic wood (wood-F) was fabricated by grafting poly(2-(perfluorooctyl)ethyl methacrylate) (PFOEMA) onto wood by atom transfer radical polymerization (ATRP). Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) with an energy-dispersive X-ray spectroscopy (EDS) showed that PFOEMA was successfully grafted onto wood. The resultant wood-F exhibited excellent water resistance with a contact angle (CA) of 156° and hysteresis of 4°. The modified wood also showed abrasion resistance, self-cleaning ability and anti-mold properties, all of which are desirable for various wood products.

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Hydrogels have drawn intensive attention as emerging materials for various applications in wearable sensors, soft robotics, and implantable devices. However, fabricating hydrogels with UV-shielding and antioxidant properties still remains a challenge. Herein, we prepared biocompatible 3-allyloxy-2-hydroxypropyl-lignin/polyacrylic acid (AHP-lignin/PAA) hydrogels with self-adhesion, conductivity, UV shielding, and antioxidant activity as wearable sensors by the incorporation of lignin into PAA. The structure, lap shear strength, and biocompatibility were characterized using the UV–vis spectrometer, universal testing machine, and cell test. The hydrogels showed strong adhesion to various substrates. The AHP-lignin/PAA hydrogels had excellent UV shielding and free radical scavenging capacity. Meanwhile, AHP-lignin/PAA hydrogels exhibited excellent sensitivity to tiny changes in low pressure. Notably, the hydrogels could adhere to the skin well without any other adhesives to monitor the movement signals of the body motion accurately. The biocompatible AHP-lignin/PAA hydrogels with self-adhesion, conductivity, UV shielding, and antioxidant activity offer great potential applications in wearable sensors.

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