Dual responsive wool fabric by cellulose nanowhisker reinforced shape memory polyurethane

The effect of promoting hydrogen bond aggregation based on PEMTC on the mechanical properties and shape memory function of polyurethane elastomers

In this work, small molecule diols named PEMTC were synthesized from isophorone diisocyanate, N-(2-hydroxyethyl)acrylamide and trimethylolpropane by a semi-directional method. PEMTC (2-(prop-2-enamido)ethyl N-{3-[({[2-ethyl-3-hydroxy-2(hydroxymethyl)propoxy]carbonyl}amino)methyl]-3,5,5-trimethylcyclohexyl}carbamate) contains hydrogen bond active site and light-initiated C=C. We introduced it as a branch chain block into poly(ε-caprolactone) (PCL). By feeding and monitoring the reaction process, we synthesized a large number of polyurethane elastomers, hydrogen bonds PCL-based elastomer (HPE), which contain a large number of dynamic hydrogen bonds. Under UV irradiation, PEMTC can make HPE molecules aggregate and cross-link, improve the degree of internal hydrogen bonding interaction of HPE materials and endow HPE materials with good elasticity, toughness, heat resistance and shape memory ability. After 270 nm UV irradiation, the elongation at break of HPE materials decreased from 607.14-1463.95% to 426.60-610.36%, but the strength at break of HPE materials increased from 3.36-13.52 to 10.28-41.52 MPa, and the toughness increased from 16.36-129.71 to 40.48-172.22 MJ m-3. In addition, the highest shape fixation rate of HPE after UV irradiation was 98.0%, and the recovery rate was 93.7%.

Changing the shape of wool yarns via laccase-mediated grafting of tyrosine

The shape of wool yarns was changed by laccase-assisted grafting of tyrosine. Prior to tyrosine grafting a cysteine pre-treatment was optimized aiming to increase the amount of thiol reaction groups available. The best operational conditions for laccase-assisted tyrosine grafting were: i) pre-treatment with cysteine (2.2 mM) in a solution of 20 % ethanol, 15 % propylene glycol and 0.5 % benzyl alcohol, pH = 10, 40 °C; ii) tyrosine grafting with 3.0 mM tyrosine, 18 U/mL laccase, pH = 5, 40 °C. The shape modification was evaluated by number of curly twists determination on the grafted yarn samples. The thermal and mechanical properties of the grafted wool yarns was evaluated by TGA, DSC and breaking strength determination. The amount of free thiols and weight gain were assessed aiming to infer the role of the cysteine pre-treatment on the final tyrosine grafting and shape modification. The laccase-assisted grafting of tyrosine onto wool yarns have influenced the thermal and mechanical properties of the yarns however without compromising their structural integrity for the final application purposes. The developed methodology to impart new shape to wool yarns is presented herein as an environmentally friendly alternative to chemical methods. The new findings revealed great potentialities for application in similar fibers like hair.

Knit Architecture for Water-Actuating Woolen Knitwear and Its Personalized Thermal Management

Personalized thermal management using water-actuated woolen knitwear has great potential for smart textile production. However, woolen knitwear exists in a wide range of forms with different derivatives. Manufacturing of smart woolen structures with excellent cooling properties is linked to certain parameters such as changes in loop formation, loop shape, and yarn arrangement upon stimulation of body fluids. To address this issue, textile knit structures with different physical and mechanical properties have been prepared using water-responsive descaled wool fibers and their smart heat and moisture regulation behavior have been investigated and compared to detect the fabric architectural effect on water actuation and cooling performance of woolen garments. The evidence suggests that the technical structure of the fabrics plays a crucial role in pore actuation and fabric cooling performance. The water actuation and thermal management abilities of single jersey were greatly enhanced because of unbalanced structures with lower mechanical stress among the loops and yarns. The experimental data is also in line with the theoretical analysis. Hence, the unbalanced structures control fast heat and mass transfer from the human body, which may offer a promising year-round clothing material to the wearer. This material can have a similar response upon contact with body sweat and humid environments and hence can act as a skinlike fabric. Their possible applications can lie in different fields, such as thermoregulation, functional clothing, sportswear, and medical care.