Preparation And Application Of Photo-cross-linkable Polyethersulfone Materials

Polyethersulfone is a kind of high-performance, full aromatic special engineering plastics. As its excellent adhesion to iron, aluminum and other metals, PES can complexed with PTFE to formed special functinal non-stick coating with many special features such as corrosion resistance, radiation resistance, good insulation, flame retardant, non-toxic, low friction and so on. However, the traditional PES paint, whether dissolved in organic solvent or dispersed in water, need to be sintered through a high temperature process nearly 400℃. The introduction of thermo cross-linked groups to PES can lower down its cross-linking temperature, but decreases slightly, which is not consistent with the current energy saving trend. UV curing is an environmental technology which can obtained a high cross-linking degree at room temperature, has lots of superiority such as environmentally friendship, high efficiency, economy, energy conservation and so on. Following the increasingly stringent requirements of environment, UV curing developes unprecedentedly, and has been widely used in electronic packaging materials, surface protection of plastic workpiece, wood floor polishment, automobile finish repairment and other industries. The introduction of UV cross-linking into PES to solve the problem of low-temperature cross-linking and increasing the solvent resistance and dimensional stability is very attractive. But for the high Tg characteristics of PES inherents, the photosensitive properties of UV cross-linkable PES preparared by the common UV curing method is not high enough to meet the demand of high-speed processing. Therefor the study of how to enhance the photosensitivity of the UV cross-linking PES is necessary. The working purpose of this paper is to investigate the methodology used to maximize the photosensitive of UV cross-linkable PES. On such a basis, an anti-corrosion coating materials will be developed. The detailed research contents and results are summarized as follows:In this paper, a novel photocrosslinkable polyethersulfone(AS-PES) was synthesized by a new monomer, 3,3'-diallyl-4,4'-dihydroxydiphenysulfone. It was characterized by FTIR, UV-vis, 1H NMR, DSC, WAXD, GPC and TGA. UV cross-linking reaction occurred with the presence of photoinitiators, and a thermoset materials was obtained. The thermal stability of cross-linked material reduced slightly compared to the former, and its thermal performance was greatly improved.Multi-functional thiolphenol CMDPS, BMPS and TMPSPB was obtained through the nucleophilic substitution reactions. FTIR, 1H NMR, and MS analysis showed that the target product was successfully prepared and had a highly yield. UV cross-linking reaction of AS-PES and thiolphenols was studied by RT-FTIR. By adding mercaptan compounds, the UV cross-linking reaction rate and the double bond conversion rate of AS-PES had been greatly improved; the reaction could carried out in the air. UV cross-linking reaction of AS-PES and mercaptan was 1:1, chain growth was the gradual increase in free radical reactions, while the chain termination was double-base termination reaction; the reaction rate Rpα[C=C]1[SH]0, that means the reaction rate was proportional to the double bond concentration and had little to do with the concentration of thiols; reaction rate raised with the thiol compounds functionality .The results of UV curing process showed that: without photoinitiator the photo-crosslinking reactions of AS-PES/BMPS coud also occured; TPO was the best photoinitiator for the suited system; light intensity greated, the light reaction rate of AS -PES/BMPS system greated. TGA curves of the cured product showed that the thermal stability of the product was cutted down by the adding of the thiol compounds, and the greater amount of thiol blended in, the greater damage appeared.The AS-PES/BMPS/P-POSS nanocomposites was prepared by solution blending of P-POSS to AS-PES/BMPS. XRD and SEM results showed that the P-POSS dispersioned in AS-PES/BMPS with a molecular size when its P-POSS content was 1 wt%, and 3 wt%, and the P-POSS crystalline phase appeared when it reached 5 wt%. Its thermal stability was markedly improved, and the composite material had a higher Tg compared to AS-PES/BMPS. When 3 wt% P-POSS was added, the tensile strength of composite increased of about 15% than AS-PES/BMPS, P-POSS had slightly effect to the elastic modulus of the material.A series of novel thiol end-capped linear polyether sulfone (M-LPES) and hyperbranched poly ether sulfone (M-HPAES) were prepared by the the nucleophilic substitution reaction of home-made chlorine capped linear polyether sulfone and hyperbranched polyarylether sulfone. By blending them with V-POSS, a new UV cross-linkable polyethersulfone nanohybrid system—M-LPES/V-POSS and M-HPAES/V-POSS were prepared. FTIR data showed that the blending system had a high crosslinking rate and a higher double bond conversion rate. XRD and SEM showed that organic-inorganic hybrid materials decentralized on nano-scale.