Synthesis Of Novel Photothermal C-S Weak Bond Initiators And Study On Initiating Polymerization Of Olefin Monomers

In recent years,with the rapid development of polymer science,synthesis of new radical polymerization initiators has always been a hot topic.In this context,our laboratory has synthesized the C-O weak bond structure of the monoester(such as ethyl benzoyl lactate)and diester initiators(such as 2,8-dibenzoyloxy Azelaic acid diethyl ester),and found that both of them could initiate the polymerization of acrylic monomers and show a good effect of initiating polymerization.On the basis of this,as the heteroatom sulfur and oxygen have a similar electronic structure,the laboratory has also synthesized some new types of initiators with C-S weak bond,found that they can also initiate polymerization.But,the efficiency of polymerization initiated by these initiators needs to be further improved.So,the subject proposed to modify the initiator,and synthesized a series of new initiators containing C-S weak bond.The modification mechanism of these type of initiators was studied.At the same time,the subject also studied on initiating the polymerization mechanism of olefinic monomer initiated by these initiators.In this paper,6-methyl-2-[(1-phenylethyl)-thio]-benzoxazole,2-[(1-phenylethyl)Thio]-benzoxazole and 6-nitro-2-[(1-phenylethyl)-thio]-benzoxazole were synthesized.The structure of three initiators was determined by FT-IR,1H-NMR,13C-NMR and MS characterization methods.Designing related experiments proved that the three initiators can initiate the polymerization of olefinic monomer.In order to study the effect of polymerization initiated by three initiators,polymerization experiments was carried out to change the polymerization temperature,polymerization time,monomer concentration and initiator concentration respectively under light and heating polymerization.What's more,some new research,the two initiators were blended according to a certain molar ratio to explore whether the active polymerization can be achieved under photo polymerization,has been carried out.The results showed that all of them could initiate heat polymerization,and 6-methyl-2-[(1-phenylethyl)-thio]-benzoxazole and 2-[(1-phenyl ethyl)-thio]-benzoxazole could initiate photo polymerization.In general,6-methyl-2-[(1-phenylethyl)-thio]-benzoxazole showed good initiation effect under heat and light initiation polymerization.As for the mixture initiation system according to a certain molar ratio,it showed a better trigger effect,although did not achieve living polymerization.Finally,the article made a simple inquiry on the initiation mechanism of this type of initiator.