Continuous Fabrication And Properties Of Flexible Carbon Nanotube/Polycarbonate Transparent Conductive Film

Transparent conductive film?TCF?is a uniform film with both good conductivity and transmittance in the visible spectrum by physical or chemical coating method.At present,indium tin oxide?ITO?plays a leading role in the market applications of TCF.However,due to the scarcity of indium and the brittleness of ITO itself,it can't meet the long-term development of flexible electronic equipments.Therefore,people have begun to explore new alternative materials,in which the combination of carbon nanotubes?CNTs?and flexible matrix are widely studied.In this paper,polycarbonate?PC?is used as matrix,multi walled carbon nanotubes?MWNTs?and single-walled carbon nanotubes?SWNTs?are employed as conductive particles.MWNTs/PC transparent conductive films and SWNTs/MWNTs/PC transparent conductive films are continuously prepared by the self-designed roll-to-roll?R2R?spraying technique,and the main contents and conclusions are as follows:?1?The continuous fabrication and properties of MWNTs/PC transparent conductive filmsUltrasonic treatment and centrifugal separation method are used to prepare the 0.01 wt%MWNTs dispersion.And MWNTs/PC transparent conductive films are prepared by R2R spraying technique.The optical and electrical properties and the content of MWNTs of films are systematically investigated as a function of the spraying cycles.The results show that the transmittance linearly decreases with the increasing spraying cycles,and the sheet resistance can't be significantly reduced after 3spraying cycles.The content of MWNTs has a linear relationship with the spraying cycles.It is considered that the MWNTs/PC transparent conductive film with 3spraying cycles?PM₃?has the optimum transparency and conductivity.Thus,we choose PM₃ for further study.The mechanical flexibility of PM₃ is systematically investigated through inner and outer bending and cyclic fatigue tests with the resistance monitoring.It is shown that the relative resistance change is not so obvious,indicating its good flexibility.Subsequently,PM₃ is simply treated by hot pressing?PM₃/HP?.The adhesive properties of PM₃ and PM₃/HP are detected by 3M tape.It is found that the interface interaction between MWNTs and PC film is significantly improved by hot pressing.Finally,the sensitive behavior of PM₃ and PM₃/HP to 3different organic vapors is investigated.The results show that the sensitivity of PM₃/HP to any tested organic vapor is significantly lower than PM₃,but the cycle stability is higher than PM₃.In addition,PM₃ and PM₃/HP have the best sensitivity and cycle stability of organic vapor for toluene.This provides an effective way for the scalable fabrication of transparent organic vapor sensors.?2?The continuous fabrication and properties of SWNTs/MWNTs/PC transparent conductive filmsTo simultaneous improve the conductivity as well as adhesion,SWNTs and MWNTs are used jointly in the following section.On the basis of the MWNTs/PC transparent conductive film with 1 spraying cycle?PM₁?,SWNTs/MWNTs/PC transparent conductive films are prepared by R2R spraying cycles of SWNTs dispersion.The optical and electrical properties of films are systematically investigated as a function of the spraying cycles.The results show that the surface resistivity of SWNTs/MWNTs/PC transparent conductive film with 1 spraying cycle?PM₁S₁?reveals a mean value of 3 kW/sq and a standard deviation of 1 kW/sq.And it still keeps good transmittance of 82%which only decreases 6%compared with PC film.To better understand the transmittance and conductivity of films,surface morphology of PM₁S₁ is observed by SEM.Subsequently,FTIR,XRD,Raman and DSC are analyzed for PM₁S₁,indicating the existence of strong interface interaction between the PC and CNTs.Then,adhesion tests and outdoor environment tests for PM₁S₁ are carried out,indicating that good adhesiveness and environmental stability.The mechanical flexibility of PM₁S₁ is systematically investigated through inner and outer bending and cyclic fatigue tests with the resistance monitoring.It is shown that the relative resistance change is not so obvious,indicating its good flexibility.At last,the opaque-to-transparent transition and switchable thermochromism of PM₁S₁ are studied.The results show that this opaque-to-transparent or color-changing can be switchable with the switch of voltage.This provides a good direction for the development of flexible smart window,which has important reference value.