| Thermochromic materials have sensitive color-changing responses to ambient temperature,and their colors can change with the temperature,realizing temperature indication and real-time monitoring,which is widely used in the fields of medical detection,wearable display,and security protection.Thermochromic textiles are intelligent textiles that are produced by applying thermochromic materials to textiles by means of spinning,printing,and finishing.Temperature-sensitive and color-changing textiles improve the added value of traditional textiles,integrate functionalization and aesthetics,and meet the needs of people for the functionalization and intellectualization of textiles.However,at present,the response of thermochromic textiles to ambient temperature is mostly adaptive,and it is difficult for people to adjust the color of thermochromic textiles according to their own wishes,which limits the application of thermochromic textiles in the field of intelligent wearables.In addition,there are some problems such as single color change and poor washable resistance in the practical application of thermochromic textiles.Therefore,it has become an urgent problem in the development of intelligent textiles to realize the active control of the color of thermochromic textiles,improve their color diversity and water resistance,and develop color-changing textiles with safety protection functions.Graphene conductive fabric was prepared by applying graphene conductive paste on the surface of the fabric by a coating method,which endowed the fabric with conductive properties and resistive heating performance.The effect of the graphene mass fraction on the viscosity of the graphene conductive paste was investigated,and the effect of the coating layers and the distance between electrodes on the conductivity of the graphene conductive fabric was analyzed.The resistive heating performance,mechanical properties,and durability of the graphene conductive fabric were investigated.The viscosity of conductive paste increases with the increase of graphene content.Both graphene conductive polyester fabric and graphene conductive cotton fabric possesses excellent electrical conductivity.With the increase of coating times,the unit resistance of graphene conductive fabric decreases rapidly,and the conductive property increases significantly.When coated with seven layers,a continuous conductive layer is formed on the surface of the graphene conductive polyester fabric with a unit resistance of230Ωcm-1.The equilibrium temperature of graphene conductive polyester fabric was 45.6℃at a voltage of 10 V.When coated with 5 layers,the graphene conductive cotton fabric has a minimum unit resistance of 130Ωcm-1,and the equilibrium temperature increases with the increase of applied voltage.Graphene conductive fabric maintains prominent mechanical properties and durability,and its thermal resistance increases with the decrease of electrode spacing.Polyaniline light-colored photothermal fibers were prepared by the wet spinning process with polyaniline as a light absorber and polyacrylonitrile as a spinning substrate,realizing the application of photothermal textiles in the field of wearable warmth.The effect of polyaniline content on the photothermal conversion performance of polyaniline light-colored photothermal fiber was explored.The low-temperature resistance,water resistance,and cycling durability of polyaniline light-colored photothermal fiber were investigated.When the content of polyaniline is 0.5 wt.%,the K/S value（700 nm）of polyaniline light-colored photothermal fiber is only 0.08,indicating the successful preparation of polyaniline light-colored photothermal fiber.Compared with pure polyacrylonitrile fiber,0.5 wt.%polyaniline light-colored photothermal fiber has remarkable photothermal conversion performance.The equilibrium temperature of polyaniline light-colored photothermal fiber reaches 48.1℃irradiated at 600 W m-2 for 600 s.With the increase of polyaniline content from 0.5 wt.%to 5.0 wt.%,the equilibrium temperature of polyaniline light-colored photothermal fiber increased from 48.1℃to 74.6℃.Polyaniline light-colored photothermal fiber maintains stable photothermal conversion performance at low temperature,and its equilibrium temperature can still reach 30.4℃even at the ambient temperature of-30.0℃.After several washing cycles and heating/cooling cycles,polyaniline light-colored photothermal fibers maintain excellent photothermal conversion performance.By measuring the photothermal conversion performance of the textiles prepared from polyaniline light-colored photothermal fibers under simulated sunlight irradiation,the application of light-colored photothermal fibers in the field of wearable heating was verified.Polyaniline（PANI）nanomaterials were introduced into polydopamine（PDA）to broaden its light absorption in the full spectrum range.Thermoplastic polyurethane（TPU）and thermochromic dye were selected as the spinning substrate and colorant respectively.The photo-induced thermochromic fiber was prepared by wet spinning with stock solution coloring technology.The effects of the content of photothermal materials on the photothermal conversion and color properties of PDA@PANI photothermal fibers were investigated.The discoloration properties,stretchability,water resistance,and application properties of the photo-induced thermochromic fiber were analyzed.The photothermal conversion performance of PDA@PANI photothermal fiber was enhanced with the increase of the photothermal material content.The equilibrium temperature of 0.5 wt.%PDA@PANI photothermal fiber reached51.1℃irradiated at the simulated sunlight of 600 W m-2 for 600 s.PDA@PANI photothermal fiber is light color,its K/S value is only 0.49 when the content of photothermal material is 0.5wt.%.The colorful photo-induced thermochromic fiber exhibits a reversible color-changing behavior with sensitive and hyperchromatic contrast under simulated sunlight irradiation.The photoinduced thermochromic fiber possesses excellent stretchability,and its elongation can reach 500%.The photo-thermochromic fabric woven by photoinduced thermochromic fiber maintains prominent photothermal conversion performance,reversible color-changing performance,and stretchability,indicating that it has a promising application in the fields of temperature visualization textiles and wearable heatersBased on the photothermal conversion performance of carbon materials under light source irradiation,the solar-responsive photothermal color-changing fabric（SPTCF）with temperature indication and the solar-driven thermochromic color-changing fabric（SDTCF）with light intensity monitoring were prepared by a coating method.The response relationship between fabric color,temperature,and irradiation intensity is established,realizing the safety protection of the human body.By exploring the influence of irradiation conditions on the photothermal conversion and discoloration properties of SPTCF and SDTCF,the relationship between fabric color,temperature,and irradiation intensity was deeply analyzed.With the increase of irradiation intensity,the photothermal conversion performance of SPTCF and SDTCF is enhanced,and the equilibrium temperature increases.Compared with the contrast fabric,SPTCF showed remarkable photothermal conversion performance.The equilibrium temperature of SPTCF is 47.1℃when the irradiation intensity is 500 W m-2.The equilibrium temperature of SDTCF irradiated at the simulated sunlight of 500 W m-2 can reach 45.7℃.SPTCF presents sensitive,high-contrast reversible photothermal discoloration.With the extension of irradiation time,the color of SPTCF(500 W m-2)gradually changed from dark blue to white.The heat on the surface of SPTCF gradually loses,the temperature drops,and its color quickly recovers to dark blue within 140 s after the light source is turned off.According to the change of irradiation conditions,SDTCF can realize the reversible transformation between green and orange and establish the relationship between fabric color and irradiation light intensity.Both SPTCF and SDTCF show good mechanical stability and cycle durability.Electro-thermochromic Janus fabric and gradient-response color-changing Joule heating fabric were prepared by coating graphene conductive polyester fabric and graphene conductive cotton fabric with thermochromic paste.Due to the Joule effect of the graphene conductive layer,electro-thermochromic Janus fabrics and gradient-response color-changing Joule heating fabrics exhibit sensitive resistance and reversible color-changing properties.Under the voltage of 10 V,the equilibrium temperature of electro-thermochromic Janus fabrics reaches 50.0℃,and their color changes from blue to white within 8 s.After the power is turned off,the temperature of the electro-thermochromic Janus fabrics decreases rapidly and reaches a balance with the ambient temperature,and its color returns to blue within 10 s,realizing the active regulation of the voltage on the fabric color.The equilibrium temperature of the gradient-response color-changing Joule heating fabric can reach 42.4℃at 8 V.With the increase of the surface temperature of the gradient-response color-changing Joule heating fabric,its color changes from purplish red（T<33.0℃）to blue（33.0℃<T<38.0℃）within 160 s,and then from blue to white（T>38.0℃）.After disconnecting the power supply,the color of the gradient-response color-changing Joule heating fabric can change from white to purple in 60 s to realize the visual temperature indication of the textile.To keep the human body warm all-weather,polyaniline was deposited on the fabric surface the by in-situ polymerization method to prepare polyaniline conductive fabric,which was encapsulated by PDMS to obtain photoelectric double induction thermochromic fabric.The resistive heating performance and photothermal conversion properties of polyaniline conductive fabrics were investigated,and the color-changing properties of photoelectric double induction thermochromic fabric were further analyzed.The surface temperature of polyaniline conductive fabric increased from 22.0℃to 40.4℃at the voltage of 8 V for 2 min.Due to the excellent photothermal conversion performance of polyaniline,the equilibrium temperature of polyaniline conductive fabric can reach 72.7℃irradiated at the simulated sunlight of 600 W m-2 for 600 s.Under applied voltage and simulated sunlight irradiation,the photoelectric double induction thermochromic fabric exhibits reversible thermochromic behavior and has temperature sensing and deicing in the process of photothermal conversion. |
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