Preparation And Properties Of Thermochromic Materials In Polydiacetylene/Metal

Polydiacetylene is polymerized by diacetylene monomers under ultraviolet light and undergoes a blue to red transition upon external stimuli.This unique light and temperature response color change characteristics make it a hot spot in the study.In the research on the thermochromic properties of polydiacetylenes,the discoloration temperature and the reversibility of the color transition are most concerned.Finding a stable discoloration matrix to improve the application performance is also the focus of attention.Metal-doped polydiacetylene is a simple method to adjust the color change characteristics,such as color,responsiveness,and reversibility.The metal ions and metal nanoparticles are doped in the diacetylene self-assembly stage to adjust the thermochromic behavior and display a variety of color change characteristics.Polydiacetylene is usually used in the sensing field,the diacetylene monomer can be finished on the fabric to prepare functional textiles with thermochromic properties,which enhances the aesthetics and gives the fabric functionality.The development of materials in the textile field is promoted,the discoloration characteristics of polydiacetylene composite materials adapts to market demand and has great application potential in temperature warning and safety protection.Taking nickel ion doping as an example,the polydiacetylene/nickel ion composite(PDA/Ni²⁺)was prepared and deposited on filter paper.The Raman spectrum shows that the peaks at 2102 cm^-1 and 1451 cm^-1 are C?C and C=C stretching of the polydiyne conjugated skeleton,which split into two peaks after heating.Due to the pulling effect of nickel ions,the peak of PDA/Ni²⁺shifts to a lower wave number.The microscopic morphology of the composite is flaky,which recrystallizes after heating,and a lamella structure is observed.PDA/Ni²⁺exhibits a two-stage color transition,showing a transition from blue to red when the temperature is raised,and turning to dark red immediately after leaving the heat source.The UV irradiation time not only deepens the color depth,but also increases the color transition temperature of the composite.The temperature rises from 76.40°C for 5 s to 105.40°C for 10minutes,resulting in a temperature difference of nearly 30°C.At the same time,the PDA/Ni²⁺composite has multiple stimulus response properties.The ultraviolet light provides the torsion driving force for the molecular chain,and finally reversibly transforms between red and deep red.DSC test results show that nickel ion doping contributes to the reversible transformation of the composite chain segment.The unique response performance of PDA/Ni²⁺composite is suitable for temperature indication in high-temperature discoloration environment and can be recycled.It has the potential to develop various thermochromic sensors and imaging equipment.In the process of self-assembly of diacetylenic monomers,nano-copper oxide particles are doped and polymerized by ultraviolet light(?=254 nm)to obtain the blue polydiacetylene/nano-copper oxide(PDA/CuO-NPS)composite.The stretching vibration peak of carboxylate ion appears in the infrared spectrum,indicating that diacetylene agglomerate on the surface of nano-copper oxide under the action of the interface,forming PDA/CuO-NPS composite with reversible thermochromic behavior.The red absorption of PDA/CuO-NPS becomes stronger at35°C,showing the color change from blue to purple.At 60°C(UV_60s),the color of the composite changes from purple to red.The photopolymerization time increases the polydiacetylene conjugated molecular chain and generates stress accumulation on the main chain,which reduces the discoloration temperature from 60°C(UV_60s)to 50°C(UV_300s).In a single heating-cooling cycle,the CR%value of PDA/CuO-NPS is as low as 5%.The low temperature environment is conducive to the reversible color change of PDA/CuO-NPS.After25 cycles,the CR%value of UV_60sPDA/CuO-NPS is still within 10%,and it has good reversible thermochromic properties.Add a certain concentration of polyvinyl alcohol aqueous solution to the unpolymerized dispersion to prepare a uniform thermochromic polydiacetylene/nano copper oxide film(PVA/PDA/CuO).Through cross-linking with polyvinyl alcohol,the discoloration temperature of the film is increased to nearly 85°C,and the film can be reversibly converted between red(30°C)and yellow(90°C).It still has good reversible thermochromism.performance after many cycles.The diacetylene monomer is attached to the surface of the polyester fiber in a dispersed state in an aqueous solution without adding other chemical substances.After high temperature finishing,it is melted and recrystallized on the surface of the fabric,and then polymerized under ultraviolet light to prepare a thermochromic fabric.The temperature affects the color rendering of diacetylene on the fabric.At high temperature,the orderly arrangement of polydiacetylene molecular chains is disrupted and the photopolymerization efficiency is reduced.The fabrics finished at 100?are evenly colored,can show obvious blue transition under short-time ultraviolet light,and have good light response performance.The color transition temperature of thermochromic polyester fabric is reduced from 75?(100?finishing)to 70?(120?finishing),which is 5?lower.After optimization,the polydiacetylene composite doped with nickel ions is finished on the fabric.The color rendering is high,and the color transition starts at 75?.The doping of nickel ions strengthens the intermolecular force,and the final color change temperature increases to 85?.The research of polydiacetylene thermochromic fabrics laid the foundation for its application in textiles.