Synthesis And Polymeric Properties Study Of New Photointiators Containing Benzophenone Groups

Photopolymerization, as a new-type environmental-friendly technology, has widely potential applications in medical and industrial aspects such as electron, medicine and biology fields for its properties of efficiency, speed and economic benefit etc. Photoinitiators are essential parts in photopolymerization system. Benzophenone, as a kind of hydrogen-capturing photointiator, has been widely used in UV-curing field due to its simplicity in synthesis and cheapness in price. However, the short absorption wavelength has limited its widely application in industry field, thus, new-type visible light photointiators containing benzophenone groups have been designed and synthesized successfully in our work, by which the UV-Visible band of photointiators could display obviously a red-shift to visible light region by connecting the different organic chromophores.Photoinitiators including C1、C2、C4、C5、C9 and C10 are used for the photoinitiation polymerization of MMA under visible light irradiation which was measured by photo-DSC, and the exothermic curves and the kinetics of this photoinitiation polymerization indicats that the photoinitiators containing electron-donating group such as methyl shows a more effective performance than that photoinitiators containing electron-drawing group such as nitro group. Simultaneously, it demonstrates that the amount of benzophenone parts contained in photoinitiators could be favorable for photopolymerization. In addition, we find that photoinitiability of photointiators is more effective than photosensitizers through comparing the kinetics of photointiators with that of photosensitizers, these results demonstrate that the active free radicals produced by the intramolecular photoinduced electron transfer process are more efficiently and frequently than that generated in intermolecular photoinduced electron transfer process.We apply electrochemical method to measure and analyze the chemical properties of photointiators and demonstrate that the chemical activity of C1 is much larger than that of C2. The further calculation by Laviron equation indicates that the number of electron transfer of C10 is much more than that of C9 in the similar chemical environment. This result means that the chemical activity of C10 is much greater compared with photointiator C9.