Study On The Preparation And Electrochromic Properties Of PMI And Its Composite Materials

Electrochromism is known as the alternative changes of colors by the application of voltages.This interesting phenomenon has led to its applications in many technological fields such as smart windows,automatic antiglazing mirrors,large-scale electrochromic screens,and chameleon materials.In this paper,we synthesized a series of maleimide resins,characterized the structures of the polymers by FTIR,and explored their electrochromic properties.In the first part,a series of novel polyimides were synthesized from bismaleimide and different diaminetriarylamines by Michael addition reaction.The prepolymers exhibited excellent solubility in common organic solvents,and then turned to polyimides by further reactions.These aromatic polyimides displayed good thermal stabilities,i.e.temperatures of 5%weight-loss exceeded 200? under nitrogen.All obtained polyimides revealed excellent stability of electrochromic characteristics,changing color from original yellowish to green.The energies of the highest occupied molecular orbital(HOMO)and lowest unoccupied molecular orbital(LUMO)of the investigated polymers were in the ranges of-4.78 eV?-4.98 eV and-1.64 eV--2.09 eV respectively.In the second part,the bismaleimide(BMI)monomer containing triphenylamine(TPA)moiety was prepared,and then reacted with different diamines by Michael-addition to obtain prepolymers.The polyimides(PIs)were obtained through heating procedure of the prepolymers.The acquired PIs had good thermostability and excellent processing properties for film casting.Cyclic voltammograms(CV)of PIs films was carried out on an ITO-coated glass substrate and exhibited two reversible redox at 0.71-0.78 V and 1.06-1.16 V versus Ag/AgCl.The electrochromic performance was investigated by spectroelectrochemical methods.These anodically colored polymer films not only showed good electrochromic properties but also exhibited high optical contrast ratio of transmittance with a color changing from yellow to green.After 100 cyclic switches,the polymer films still maintained excellent stability of redox and electrochromic activity.In the third part,maleimide containing carbazole was acquired through a two-step method.The obtained maleimide,vinylcarbazole and graphene were generated composited through radical reaction in the present of initiator.The prepared composite had good thermal stability,good film-forming property and excellent electrochromic property due to the high charge mobility of carbazole.This paper has provided some methods and ideas for design and synthesis a new type of multifunctional polymer materials,and a certain theoretical support to understand the electrochromic mechanism of multi-functional polymer.