Jin-Lian Hu

By Suman Thakur and Jinlian Hu

Shape memory polymer (SMP) is a stimuli-responsive material with the ability to alter a programmed shape to its original shape upon triggering of an appropriate stimulus. For the past decades, SMP has dragged much interest in material field owing to its various and versatile applications. One archetypal SMP is polyurethane, which has a wide-ranging transition temperature for its shape recovery, retraction temperatures, inherent soft-hard segments, a high recoverable strain (up to 400%), high control of the softening, favorable and tunable physical properties, and so on. This chapter emphasizes on the raw materials required for the synthesis of shape memory polyurethane (SMPU), the principle of shape memory function, the design of protocol of SMPU, and their applications with future directions.

Part of the book: Aspects of Polyurethanes

By Qian Wu and Jinlian Hu

Textile, as an intimate partner of human body, shows promising application in wearable thermoelectrics for body heat conversion. Compared with other widely studied flexible film thermoelectric materials, textiles having better air-permeability, wearability, and flexibility are more suitable for wearable electronics. In the past few years, many researches have focused on the design and fabrication of textile-based thermoelectric materials and generators. By integrating with high performance inorganic semiconductors and conductive polymers, fabrics or fibers will be given thermoelectric properties. Technologies of coating, printing, and even thermal drawing can be adopted in the fabrication of textile thermoelectric materials. With great design flexibility, various flexible textile generator structures can be obtained by using yarns or fabrics as thermoelectric legs, which will bring new inspirations for the future development of flexible thermoelectrics.

Part of the book: Bringing Thermoelectricity into Reality

By Xueliang Xiao and Jin-lian Hu

In the past thousands of years, keratin fibers were only considered as textile fibers for excellent fiber performances, such as high strength, acceptable elasticity, good thermal insulation, etc. Only recently, some indications have been obtained that keratin fiber may be a smart natural material that may subvert people’s perception of this matter. The smart attribute displays shape memory effects (SMEs) responsive to many types of stimuli including water, heat, coupled water-heat, redox agents, UV light, etc. These smart functions of keratin fibers are found to be the result of three structural components: crystals, hydrogen bonds (HBs), and disulfide bonds (DBs) among intra- and inter-keratin macromolecules. In this chapter, keratin fibers (such as camel hair) were employed for investigating their SMEs under five types of stimuli, in which the HBs, DBs, and crystals were characterized separately, as well as the fiber shape fixation and recovery ratios, respectively. The whole test results indicated that keratin hair fiber is a type of shape memory polymer and the related SME depends on the contents of the HBs, DBs, and crystalline phase inside the hair.

Part of the book: Keratin