Study On Chemiluminescence Induced Free Radical/Cationic Photopolmerization

Photopolymerization with the characteristics of energy saving,environmental protection,high efficiency and speed has been widely used in the fields of coatings,3D printing,optical devices and polymer synthesis.At present,most photopolymerization reactions are completed under the irradiation of external light sources,such as mercury lamps,LED lamps or lasers.These light sources not only require continuous external energy supply and complex equipment,but also the limited penetration depth of light,leading to the limited application range of photopolymerization.Chemiluminescence(CL)is the process of generating photons through chemical reactions in chemical or biological environments.CL has the advantages of great biocompatibility,uniform light intensity,flexible selection of light-emitting sites within the system,etc.,which can effectively make up for the shortcomings of traditional light sources in photopolymerization.In this article,CL is used as the internal light source to induce the decomposition of free radical/cationic photoinitiators,and then initiate free radical/cation photopolymerization reactions,and further realize the post-functionalization of photopolymerization materials.In the first part of this article,CL induced photopolymerization of thiol-ene was studied.Peroxyoxalate CL(PO-CL)system is used as a light source to excite the free radical photoinitiator I-819 to undergo photolysis,and then generate active free radicals.The generated active free radicals can effectively initiate the free radical photopolymerization reaction of thiolacrylate and thiol-allyl systems in the presence and absence of oxygen.On this basis,hydrogel was prepared by CL induced thiol-ene photopolymerization,which has potential application value in the field of biomedicine.In order to further expand the application scope of CL induced photopolymerization,the second part of this article uses long conjugated sulfonium salt as a cationic photoinitiator to explore CL induced cationic photopolymerization.Sulfonium salt can break the S-C bond under CL irradiation,and the generated protic acid can induce photopolymerization of three common cationic monomers,cyclohexene oxide,N-vinylcarbazole and n-butylvinylether.In addition,CL induced cationic photopolymerization has dark reaction characteristics,which can effectively improve light utilization efficiency.Furthermore,CL induced the photocrosslinking reaction of multifunctional cationic monomers,and prepared functional materials with aggregation-induced emission effect.Considering that long conjugated sulfonium salts have complex synthetic routes and poor solubility,the third part of this article uses commercial ferrocenium salts(I-261 and I-262)as visible light cationic photoinitiators to explore CL induced cationic light polymerization.The end of absorption wavelength of ferrocenium salts can be extended to the visible light region,which can match the emission wavelength of CL.Under CL irradiation,both ferrocenium salts can undergo photolysis,and the Lewis acid produced can effectively induce cationic photopolymerization of cyclohexene oxide,N-vinylcarbazole and n-butylvinylether.The influence of initiator concentrations,initiator types and different cationic monomers on photopolymerization kinetics were systematically studied.Furthermore,CL induced the photocrosslinking reaction of multifunctional cationic monomers to prepare functional materials with upconversion emission effects.