| Optical characteristics,as the most important function and visual form of clothing and fabrics,are particularly critical for their intellectualization(controllable/reversible adjustment of optical reflectance,transmittance,absorbance,and emissivity).The smart color changes of clothing have broad application prospects in adaptive camouflage,wearable display and so on.In various smart color-changing methods,electricity responsive color-changing materials or devices control the changes of optical properties of materials or devices through the portable and controllable way of "electricity",which provides a potential development direction for realizing smart color-changing clothing and textile.Although electricity responsive color-changing devices(including electrothermochromic devices and electrochromic devices)have the advantages of good controllability and multi-color,for smart clothing applications,they still face the problems and challenges of insufficient conformability of complex force field,air/vapor permeability and multi-band regulation.In view of the above problems,starting from the perspectives of deformable microstructure regulation,device fibrosis design and multi-band functional integration,the stretchable color-changing devices were constructed by preparing transparent stretchable conductive films with semi-embedded wrinkled structure;The long electrochromic fibers were prepared by building continuous preparation equipment and designing parallel dual-counter electrode device structure;Utilizing the infrared regulation characteristics of carbon nanotubes and grid design,the infrared electrochromic devices based on carbon nanotubes were prepared,which given the devices excellent stability under the tensile force field and air/vapor permeability,realized the visible-infrared dual-band electrochromic effect,and promoted the application of electrochromic devices in smart clothing.The main research contents are as follows:Stretchable electrothermochromic devices based on semi-embedded wrinkled structure: Aiming at the problem that the stability of stretchable color-changing devices is seriously affected due to the poor stretchable stability of conductive substrate.The semi-embedded wrinkled structure of Ag NW was formed by successively spraying Ag NW and spin-coating pre-polymerized PDMS solution on the surface of pre-strained PDMS film.The spin-coated ultra-thin PDMS layer enhanced the adhesion between Ag NW and PDMS substrate,reduced the fractures of Ag NW caused by stretching,and highly enhanced the stretchable stability of Ag NW/PDMS composite film,which showed good conductivity after 500stretching/releasing cycles at 40% and 60% strain.Utilizing the good resistance-heating effect of stretchable Ag NW/PDMS composite film,the stretchable electrothermochromic device was prepared by screen-printing thermochromic ink,which could realize reversible color changes from purple to blue to colorless and patterned display by applying different currents or strains,switching time was 35 s and 45 s,respectively.The stretchable electrothermochromic devices showed good color-changing stability after 100 stretching color-changing cycles.Stretchable electrochromic devices based on semi-embedded wrinkled structure: Compared with electrochromic devices,electrothermochromic devices are still vulnerable to ambient temperature and consume more energy,but the poor electrochemical stability of Ag NW limits its application in electrochromic devices.Therefore,silver@gold core-shell nanowires(Ag@Au NW)were prepared by epitaxial growth of gold coating on the surface of silver nanowires,which effectively prevented the interaction between Ag NW and ions in the electrolyte and significantly improved the electrochemical stability of the conductive layer.The Ag@Au NW/PDMS composite film with the semi-embedded wrinkled structure was used as the transparent stretchable conductive electrode.The electrochromic gel electrolyte which was suitable for Ag@Au NW/PDMS composite film was prepared based on viologen electrochromic material.The stretchable electrochromic device was assembled based on the all-in-one structure,which could realize reversible color changes between yellow and green at-0.9 V and 0 V.It had a good electrochromic effect and stability under 180° bending and 40% strain.Electrochromic fiber based on parallel dual-counter-electrode structure: In order to improve the integration and comfort of electrochromic devices for smart clothing,electrochromic fibers with the parallel dual-counter-electrode structure were prepared based on various viologen electrochromic materials through continuous processing equipment and realized the continuous preparation of multi-color electrochromic fiber(?100 m).Thanks to the parallel dual-counter-electrode structure,the electrochromic fiber showed more uniform electric field distribution,and highly improved the long-range electrochromic uniformity of the fiber.The electrochemical stability of electrochromic fiber was effectively improved by coating the ITO layer on the metal electrode,and it showed good color-changing effect after 300 cycles.The PE protective layer on the outer layer of the fibers ensured the good stability of the electrochromic fibers under a variety of environmental conditions(such as mechanical,washing,irradiation,and thermal stability).In addition,electrochromic fibers could be woven into large-area smart textile and be implanted into the commercial textile to form various complex patterns to show different color changes(blue,magenta,green and dark red)under different applied voltages,which shows the potential applications in wearable displays and adaptive camouflage.Flexible infrared electrochromic device based on grid structure: In addition to electrochromic devices in the visible band,the regulation of the infrared band has attracted more and more attention.The infrared electrochromic device based on SWCNT was prepared by assembling filtered SWCNT/PVDF films.It could achieve good infrared regulation effect under different applied voltages due to the adsorption/desorption and doping/de-doping of cations and anions in the electrolyte in the SWCNT electrode.The emissivity changes of SWCNT/PVDF device under different voltages could reach 0.52 at the background temperature of 40°C,the surface infrared temperature changes of the device could reach 12.7°C,and it remained 70%infrared regulation effect after 300 cycles.The infrared transparent electrodes were prepared through the grid structure design of the SWCNT layer.The infrared transmittance of infrared transparent electrodes could reach 70% and the visible light transmittance could reach 75%.The electrochromic devices with visible-infrared dual-band regulation were prepared by using PEDOT: PSS as the electrochromic layer and combining with the infrared cooperative regulation of SWCNT grid,which could realize the reversible color changes between light blue and dark blue in the visible band and the infrared emissivity regulation of device in the infrared band.It has wide application prospects in adaptive camouflage and human thermal management,and lays a foundation for the visible-infrared dual-band adaptive camouflage. |
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