Synthesis And Properties Research Of Photosensitive Polyimide

Due to high temperature working environment, optical fiber coating not only needs to satisfy ordinarily performance but also to meet the requirement of heat-resistant in some fields. Photosensitive polyimide(PSPI) that possess both heat-resistant and sensitive properties has attracted great interests in many fields, such as microelectronic industry, avigation, photoelectricity and so on. By making use of UV curing technique, the modifying PSPI can be used as oligmer to develop heat-resistant optical fiber coating.On the basis of reference to synthetic methods of Polyimide, PSPIs' molecules were designed and technical process was selected . PSPIs were prepared by the method of solution polycondensation at room temperature and chemical imidization at high temperature, which selectting hydroethyl acrylate(HEA), pentaerythritol triacrylate(PETA) and maleic anhydride(MA) as photosensitive group respectively. It is find that the properties of PSPI which end-capped with MA was better. photosensitive group was introduced successfully and the heat- resistant property was remained. In this paper, reaction kinetics was also studied.In order to improve the Solubility of PSPI, a series of cocondensation type PSPIs that end-capped with HEA have been synthesized from phyromellitic dianhydride (PMDA), 4,4'-diaminodiphenyl ether (ODA), dimethyl phenylamide(DMPA) and diamino-diphenyl sulphone(DDS). Their properties and structures were characterized by the means of Fourier transform infrared spectroscopy (IR), differential scanning calorimetry(DSC), thermogravimetric analysis (TGA), X-ray powder diffraction (XRD) and so on. The relationships between structure and properties of PSPIs were discussed. Experiment results show that the solubility and crystalline were improved by copolymerization method. At the same time,the excellent heat-resistant properties of PSPIs were maintained.The kind and mole ratio of diamines have some impacts on the properties of PSPIs.The intrinsic viscosity of PSPIs was 1.08dL/g~1.38dL/g. The sequence of thermal stability was PSPI(I) >PSPI(III) >PSPI(II).Their thermal decomposition temperatures all above 530℃.The glass transition temperature showeda similar change tendency as that of the thermal stability,which was 319.30°C,298.62°C,293.30°C. At the same time,the properties of UV curing coating by using PSPI( II) as oligmer was tested.