Textiles with heat management have good effects on improving comfort during sports. However, it is still a great challenge to endow textiles with responsiveness to external environmental changes. Herein, we developed a temperature-regulating cotton textile with multiple heat transfer capabilities by a two-step method. Firstly, hydroxylated boron nitride (BN-OH) nanosheet dispersion liquid was prepared using the ultrasonic-alkali treatment. Subsequently, enzymatic graft polymerization of N -isopropyl acrylamide (NIPAM) onto cotton fibers was performed using horseradish peroxidase. The composite cotton fabric, containing entrapped BN-OH, exhibits unique temperature-regulating ability. The thermal diffusivities in lateral and in-plane directions reach 1.3 and 1.7 times of the untreated, respectively. This can be attributed to the temperature responsiveness of poly-NIPAM (PNIPAM) and the increase in the packing density of the thermally conductive nanosheets at high temperatures. Meanwhile, the PNIPAM covering the fiber surfaces expands at low temperatures, accordingly minishes the gap sizes between fabric yarns and endows the fabric with improved heat preservation effects. The present work provides an enzyme-mediated strategy for developing textiles with ambient temperature self-response ability. Graphical abstract
Lei Jin,Yonggang Shangguan,Tao Ye,Hu Yang,Quanfu An,Qiang Zheng
A remarkable shear induced self-thickening of chitosan-graft-polyacrylamide aqueous solution was observed. After the polyelectrolyte solution presenting shear thinning was subjected to a high-rate shear for several minutes, their viscosities recovered and then a much higher zero shear viscosity than the original one appeared. Obviously, the self-thickening differs from conventional shear thickening or viscous recovery, as reported previously. The mechanism of self-thickening was investigated by rheological methods together with TEM, 1H NMR and DLS, etc. It was found that some aggregates exist in original chitosan-graft-polyacrylamide aqueous solution and the scale of such aggregations would become larger within several minutes after a strong shear. The thickening was proven to be the result of an enhanced scale of GPAM aggregation in aqueous solution, and the mechanism of aggregation was proven to be intermolecular hydrogen bonding effects. Besides, the shear-induced self-thickening appears to be facile, maintainable and easily controllable by changing the shear conditions.
To augment the functional attributes of pectin and expand its prospective utilization in food preservation, this research explored the enzymatic grafting of resorcinol and 4-hexylresorcinol onto pectin. Structural analysis verified the successful grafting of both resorcinol and 4-hexylresorcinol to pectin via esterification , with the 1-OH of resorcinol and 4-hexylresorcinol and the carboxyl group of pectin functioning as grafting sites. The grafting ratios of resorcinol-modified pectin (Re-Pe) and 4-hexylresorcinol-modified pectin (He-Pe) were 17.84 % and 10.98 %, respectively. This grafting modification notably enhanced the antioxidative and antibacterial properties of pectin. Specifically, DPPH clearance and the inhibition ratio in the β-carotene bleaching assay increased from 11.38 % and 20.13 % (native pectin, Na-Pe) to 41.15 % and 36.67 % (Re-Pe), and 74.72 % and 53.40 % (He-Pe). Moreover, the inhibition zone diameter against Escherichia coli and Staphylococcus aureus rose from 10.12 and 10.08 mm (Na-Pe) to 12.36 and 11.52 mm (Re-Pe), and 16.78 and 14.87 mm (He-Pe). Additionally, the application of native and modified pectin coatings effectively impeded pork spoilage, with the modified pectins demonstrating a more potent effect. Among the two modified pectins, He-Pe exhibited the most significant enhancement in pork shelf life.
危险品化学品经营许可证（带存储）