| Photobase generators as a new initiator, it can produce free radicals and amines under UV irradiatiton. In this paper, two ketoneammonium organoborates and their polymers were synthesized by2-(Dimethylamino)ethyl methacrylate and tetrapheny-boron anion.The structure of products and the intermediates were characterized by melting point、UV-vis、FT-IR、H1NMR、TGA.The relationship between photophysics of these quaternary ammonium salts and structures was investigated, the photoactive-ties of those salts were also studied.1. These salts were synthesized by two steps and the structure of products were confirmed by UV-vis, FT-IR and H1NMR. Ⅰ-2is acetophenoneammomium salt, Ⅱ-2is4’-Hydroxyacetophenone ammomium salt. Ⅰ-3、Ⅱ-3were their polymers. The TGA and their melting point showed their good thermal stability.2. The photophysics of quaternary ammomium salts showed that the wavelength range of their UV absorption is between220nm-350nm in acetonitrile. The λmax of absorption only depends on the chromophore. Neither the tertiary amine including substituents on the nitrogen atom nor the structure of the counterion had much influence on either the extinction coefficient or the wavelength of maximum absorption. The wavelength of maximum absorption of Ⅱ-3is about310nm, showed the "red shift" with intramolecular hydrogen bonds.3. The kinetics of photolysis of quaternary ammomium salts in acetonitrile was determined. The results showed that the photolysis reaction of PBGs is a first-order reaction. For Ⅱ-2,the kinetic equation of the photolysis reaction is:Rd∝0.887[Ⅰ]. Solutions of Ⅰ-2、Ⅱ-2were prepared by dissolving Ⅰ-2、Ⅱ-2(0.01mmol) in a mixture of DMF(8mL) and H2O (2mL). The changes in PH were observed as a function of the irradiation time upon irradiation with UV light. The PH of Ⅰ-2increased from7.43to9.61, and the Ⅱ-2increased from6.98to9.08.4. The photopolymerization kinetics of TMPTA、HDDA and PUA photoinitiated by the quaternary ammomium salts were monitored. The influence of temperature, initiator concentration and atmosphere on photopolymerization was investigated. The results surgested that the quaternary ammomium salts can initiate the free radical photopolymerization efficiently. For the air system, the reactivity decreased in the order of:Ⅱ-3>Ⅰ-3>Ⅱ-2>Ⅰ-2; In N2, the reactivity decreased in the order of: Ⅱ-2>Ⅱ-3>Ⅰ-3>Ⅰ-2.5. After UV irradiation, The salts can generate bases which can initiate the thermal curing of epoxy compounds. The curing of epoxy resin(E-44) was studied by using different salts after UV irradiation. Under the same condition,the conversion of epoxy group depends on the salts. the curing conversion decreased in the order of:Ⅱ-3>Ⅰ-3>Ⅱ-2>Ⅰ-2.6. The conversion of epoxy group depends on the curing temperature, prebake and postbake can improve the conversion of E-44more effective.The conversion can reach82.1%. |
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