The Synthesis And Properties Of Free Radical Photoinitiator With Low Migration And Toxicity

Photopolymerization technology is widely used in many fields because of its environmental protection. The photoinitiator is the key component in the photopolymerization system. It can produce active species through the chemical action to initiate the polymerization of system after absorbing light energy. However, photoinitiators with low molecular weight are easy to migrate to the surface of curing materials. The odor and toxicity will limit their application. Besides, in terms of the Norrish ? photoinitiators, tertiary amines are mostly applied in industry among H-donors. But tertiary amines at high concentrations have toxicity and strong odor, and it will affect the properties of end-products. The results showed that the migration ability of photo initiators is correlated with the relative molecular mass, and the migration ability of the photo initiators with high molecular weight is obviously decreased. The introduction of hydrogen donor groups into the molecular structure of the traditional Norrish II photoinitiators can reduce the adverse effect of amines in a certain extent.The purpose of this thesis is to prepare some free radical photoinitiators with low biological toxicity and low migration, but high initiating reactivity.The following are the main research contents and conclusions:(1) Two one-component Norrish II photoinitiators, MBPAcMP and MBPMP, are synthesized in this work. The polymerization kinetics at different condition is investigated by real-time infrared spectroscopy. The properties of UV absorption, photodegradation and migration are studied by UV absorption spectra. The cytotoxicity of materials is tested by MTT method. The results show the maximum absorption wavelength of MBPAcMP and MBPMP don't change significantly compared with MBP,but their photodegradation rates are both higher than those of MBP. After irradiating for 10 min, the absorbance at respective maximum absorption wavelengths of MBPAcMP, MBPMP and MBP decreased 20%, 11% and 3.4% respectively. MBPAcMP and MBPMP have high initiating reactivity when initiating the photopolymerization of monomer alone. The rate of migration of the photoinitiators remained in the curing system from the interior of the material to the surface is lower than that of the MBP/EDAB photoinitiation system. The materials obtained by the photopolymerization initiated by MBPAcMP and MBPMP have better biocompatibility and lower cytotoxicity than the material obtained by MBP/EDAB.(2) Two one-component bifunctional photo initiator, MBPAcPA and MBPPA are synthesized. Photodegradation of MBPAcPA and MBPPA are monitored by UV absorption spectra, both of them have high photodegradation efficiency. After irradiating for 10 min, the absorbance at respective maximum absorption wavelengths of MBPAcPA and MBPPA decreased 39% and 19% respectively, which is higher than MBP. The kinetics of photopolymerization show MBPAcPA and MBPPA with high initiating activity are efficient one-component Norrish ? photoinitiators,which can reduce the use of the amine in the system. Under the condition of the same molar concentration of light-absorbing group in the photoinitiator system, the final conversion rates of carbon carbon double bond initiated respectively by BP, MBPPA and MBPAcPA are 71%, 91% and 95%. Since the relative molecular mass of the two photoinitiators is high, their migration properties are degraded. Moreover, residual MBPAcPA and MBPPA can be incorporated into the cured product by amine alkyl radical during the photopolymerization process, which can reduce the migration of residual photo initiators and the toxicity of curing coating. The results of cytotoxicity test showed that the OD values of curing films obtained by the photopolymerization initiated by MBPPA and MBPAcPA are not significant different from those of the negative control, which means that MBPPA and MBPAcPA are non-toxic to L929 cells.(3) Bifunctional Norrish I photo initiator (1173AcPA) with low migration are synthesized. The test results show that the photodegradation rate and photo intiating activity of 1173 Ac PA have declined compared with Irgacure(?)1173. The intensity of the absorption peak at 243.6 nm of 1173AcPA decreased 44% after irradiating 120 s, which is lower than Irgacure(?)1173. Overall, 1173 Ac PA has certain photo initiation performance,the final conversion rates of EOEOEA initiated by 1173AcPA can reach 98%.We can know that the rate of migration of the 1173 Ac PA is lower than Irgacure(?)1173 by analyzing the migration performance of residual photo initiator in the curing product, which can reduce the toxicity of curing coating. The effects of different factors on photopolymerization are investigated by real-time infrared spectroscopy. The results show that the photopolymerization rate and the final double bond conversion of the monomer are enhanced with the increasing of the concentration of photo initiators and the light intensity. The more functionality of monomer has, the lower of the double bond conversion is. The in vitro cytotoxicity of the materials is characterized by MTT method. It turns out that the OD values curing film obtained by the photo polymerization initiated by 1173AcPA can reaches 99% of those of the negative control, and the film have good cell compatibility, which means that it's non-toxic to L929 cells.