Study On The Fabrication And Stability Of Multifunctional Silver Nanowires-based Transparent Conductive Film On Polycarbonate Substrate

Polycarbonate(PC)transparent parts have been widely used in aerospace,national defense and other fields because of their excellent comprehensive performance.On the basis of considering both optical and mechanical properties,PC combined with functional coating would be endowed with more performances.For example,conductive coating could serve as transparent electrode,electric heater and so on.As a new type of transparent conductive material,silver nanowires(AgNWs)have been widely used as transparent conductive films due to their excellent conductivity,high transmittance and high aspect ratio.AgNWs also exhibit great engineering value as conductive functional coatings on transparent polymer substrates.However,it is difficult for AgNWs to be well dispersed and bonded on PC because that PC surface has few active groups and shows poor hydrophilicity.In addition,high contact resistance of AgNWs also needs to be addressed.In this thesis,the transparent conductive AgNWs film was fabricated on PC through the substrate modification and vacuum assisted hot embossing(VHE),and its stability in various extreme environments,applications in electric heating and electromagnetic shielding were studied.The main contents are as follows:(1)The effects of the modification time of polydopamine(PDA),the spinning cycles of AgNWs solutions and the process parameters of VHE on the photoelectric properties and stability of transparent AgNWs conductive films coated PC(PDA@PC/AgNWs)were investigated.The results shown that PDA with abundant functional groups such as hydroxyl and amino groups could improve the hydrophilicity of PC and the dispersion of AgNWs on PC surface.Furthermore,the VHE process caused welding of lap joints between AgNWs and effectively reduced the contact resistance of AgNWs without loss of transparency.Additionally,the AgNWs network could be semi-embedded in the PC substrate by VHE process,so that the film could maintain good electrical conductivity after hydrothermal aging and ultraviolet radiation for 168 h,respectively,and exhibited excellent stability when subjected to for more than 100 times and mechanical bending for 2000 times.These properties make the transparent conductive films on transparent polymer substrate show great potential in practical applications.(2)Tannic acid(TA)was used to modify the surface of PC,combined with the optimized VHE process,TA@PC/AgNWs thin film with high transparency,low sheet resistance,excellent stability was obtained.The high light transmittance and abundant hydrophilic groups of TA endowed the conductive film with high transparency(82%),and well hydrophilicity.Furthermorelow,the VHE process would reduce the sheet resistance to 11.2(?)/sq.In terms of electric heating function,the film could be heated to 55 ~oC only after 25 s under 5 V DC voltage,which had a fast response time,and the temperature distribution is uniform,showing good defogging performance.In terms of electromagnetic shielding,the shielding effect of single-period film in the X band(8.2～12.4 GHz)was about 26.8 d B.By preparing multi-period thin films,the shielding efficiency was increased to 41 d B,and it still maintained 90%electromagnetic shielding effectiveness after 1000 cycles of bending.