Infrared Variable Emissivity Properties Of Polyaniline Films / Devices In Ionic Liquid

Polyaniline(PANI)infrared variable emissivity devices have excellent infrared control and thermal radiation control capabilities,and have broad application prospects in the fields of dynamic infrared military camouflage and spacecraft thermal control.At present,PANI films still have problems in large-area and high-quality preparation.At the same time,infrared variable emissivity devices based on functional films still have long response time and short electrochemical cycle life in terms of performance.These problems stem in part from the electrolyte materials used in the devices,which can be solved by developing high-performance electrolyte materials.Here,a high-quality PANI film was prepared by V₂O₅ in-situ deposition,and from the perspective of the design of the electrolyte layer material,the ionic liquid electrolyte system doped with different lithium salts was explored on the infrared emissivity adjustment performance,response rate and response rate of the functional film and the device.The influence of electrochemical stability,finally based on the preferred electrolyte system and PANI film together to construct an infrared variable emissivity device with excellent comprehensive performance.The specific research content and results of this paper are as follows:The PANI film based on Dodecylbenzenesulfonic acid(DBSA)was prepared by electrochemical polymerization,which showed excellent infrared electrochromic performance.This is because the relative molecular mass of DBSA is very large,which promotes a higher degree of charge delocalization on the PANI molecular chain,and improves the stability and conductivity of PANI.Then,the electrochemical performance and infrared emissivity adjustment performance of the DBSA doped-PANI film when cycled in five lithium salt-doped ionic liquid(IL)electrolyte systems were investigated.The study found that the functional film is in 1-butyl-3-Methylimidazole tetrafluoroborate-Lithium tetrafluoroborate(BMIBF₄-Li BF₄)ionic liquid electrolyte system when circulating,showing higher infrared emissivity adjustment performance,and its??value in the 2.5-25?m band is 0.37.This is because in the redox process of PANI,the ionic liquid and the lithium salt contain the same anion BF₄^-,which increases the ion concentration.At the same time,the ion size is small,which helps it to be fully doped in the PANI film.At the same time,the film also has a faster response rate(attachment/fading time is 16.0 s/4.25 s)and excellent cycle stability.Finally,based on the preferred electrolyte system,an electro-variable emissivity device was constructed together with the PANI film.The device has excellent infrared adjustment ability,its??value in the 2.5-25?m band is 0.32,and it shows good thermal radiation adjustment ability,and the device has a fast response rate(attachment/fading time is 6.75 s/4.49 s)and excellent cycle stability.The PANI film was prepared by in-situ chemical oxidation.First,the influence of oxidant(V₂O₅ thickness),doped acid and in-situ polymerization time on the infrared electrochromic properties of the prepared film was investigated.The optimized process parameters were as follows:The thickness of the oxidant layer is 900 nm,the in-situ polymerization time is 8 h,and the doping acid is camphor sulfonic acid(CSA).Then we further investigated the infrared electrochromic performance of the PANI film when cycling in different IL electrolyte systems.The study found that the functional film exhibited higher infrared emissivity adjustment performance when cycling in the BMIBF₄-Li BF₄ IL electrolyte system.The??value in the 2.5-25?m band is 0.23.At the same time,the film also has a faster response rate(attachment/fading time is 6.63 s/2.86s)and excellent electrochemical stability.Finally,based on the preferred electrolyte system,an electro-variable emissivity device was constructed together with the PANI film.The device has good infrared heat radiation control ability,and its??value in the 2.5-25?m band is 0.23.At the same time,the device has a fast response rate(attachment/fading time is 10.94 s/6.52 s)and excellent cycle stability.