Study On Properties Of Gradient Polymer Initiated By Polymerizable Polysiloxane Photoinitiator And Synthesis Containing-Si Bisacylphosphine Oxide Photoinitiator

UV curing technology is a kind of environment-friendly green technology in which photoinitaitors play an important role. The photoinitiators significantly iniflucence the degree and rate of photopolymerization, which have a direct impact on the performance of UV curing materials. Therefore, the photoinitiators with special function, high efficiency and environmental protection have drawn much attention. In this paper, we firstly investigated the gradient distribution of the degree of the photopolymerization initiated by the polysiloxane-based polymerizable photoinitiator and gradient properties of the obtained gradient polymer, and their internal connection. Moreover, It is difficult to prepare gradient material with integrated performances only depending on a single component or molecular weight gradient, which will restrict its application. Hance, it is important to design and synthesize containing silicon macromolecular photoinitiator for the preparation of double or multiple gradient polymers. Bisacylphosphine oxide (BAPO) can initiate secondary polymerization of monomers by the irradiation of different wavelength light. Based on the feature of BAPO, we design containing-Si bisacylphosphine oxide photoinitiator (Si-BAPO) which combine the low surface tension and energy of polysiloaxane and the feature of BAPO. The photoinitiator Si-BAPO not only control molecular weight gradient, but also component gradient, because Si-BAPO can spontaneously form concentration gradient and condary polymerization of monomers, which will provide a simple, controllable and environmentally friendly method for preparing double gradient polymer. The synthesis reaction of Si-BAPO was studied, which can provide theoretical basis for the preparation of double gradient polymer.The detailed research contents and conclusions are as follows:1、The properties of photoinitiator HHMP-Si-CC were investigated. The UV absorption spectra showed that HHMP-Si-CC had a maximum absorption peak at 275nm. The kinetics of photopolymerization indicated that HHMP-Si-CC efficiently initiated photopolymerzation. HHMP-Si-CC had relatively good self-floating ability and spontaneously formed a gradient distribution of concentration in the monomer after standing for a designated time. The film prepared by using HHMP-Si-CC had good hydrophobic property. The polymer initiated by HHMP-Si-CC presented a gradient change in the degree of polymerization, molecular weight, thermostability and glass transition temperature (Tg.). SEM images of curable films initiated by HHMP-Si-CC mitigated the oxygen inhibition to a certain degree due to the enrichment of the photoinitiator HHMP-Si-CC in the surface. Moreover, high performance liquid chromatography (HPLC) demonstrated that the migration of photolysis fragments of HHMP-Si-CC toward the cured material surface was mitigated significantly. The film initiated by HHMP-Si-CC had good yellowing resistance.2、The synthetic routes of Si-BAPO were discussed. We found that the C-P bond is very weak that easily is influenced by the catalysts and reaction conditions. The purification method of BAPO is improved. The by-products were washed by solvents to avoid the loss of products in the silica gel chromatography and the yield of BAPO is increased.3、The carbonylation reaction of C-P bond was tried based on bromobenzene and diphenyl phosphine as raw materials. However, the carbonylation reaction has failed due to the unsuitable experimental conditions.