Storage Stability Of Thiol-ene And Application In Photopolymerization

As an environmentally friendly green technology,photopolymerization has been widely studied based on the advantages of fast-curing,low-pollution,energy-saving,and excellent performance of polymers.With the development of photopolymerization technology is gradually becoming comprehensive,thiol-ene photopolymerization has triggered a wave of research and exploration based on various advantages,and its application in the field of photopolymerization has been flourishing.However,the poor storage stability limits the application of thiol-ene photopolymerization to the large-scale industrial development.For specific thiol-ene systems,the reaction mechanism is also unclear and lacks sufficient studies.Although various schemes have been reported to improve the storage stability of thiol-ene systems,they all have various defects.Therefore,the study of the reaction mechanism and storage stability of thiol-ene is of great significance for its development.In this research,the storage stability of thiol-ene and application in photopolymerization were investigated.The main researches were as follows:1.The storage stability of several thiol-ene systems was systematically investigated using the primary and secondary thiols.Among them,the diethylbenzene(DVB)system exhibited the best normal and high temperature storage stability,which was attributed to the moderate double bond electron cloud density,the conjugated structure and the low activity of the chain propagation product.The reaction mechanisms were clarified for specific thiol-olefin systems,such as DVB system,acrylate(TPGDA)system and triallyl isocyanurate(TTT)system by introducing base catalyst(DBN)and phenolic stabilizer(MHQ).2.The effect of thiol substitution on the thermal,mechanical and optical properties of the system has been investigated in radical thiol-ene photopolymerization.2° thiol has lower photopolymerization activity.In terms of polymer properties,for TTT systems with no chain growth,there is basically no difference in hardness,network thermal properties and glass transition temperature(Tg)between the primary and secondary thiol systems,with slight differences in optical and swelling resistance properties due to differences in the proportion of elemental sulfur and the influence of methyl groups;For DVB and TPGDA systems with chain growth,the differences in performance are mainly due to the different network content of thioether bond caused by the different thiol conversion rates.3.Combining the advantages of the DVB system,photoinduced thiol-ene optical adhesives with high stability storage were prepared using4-mercaptomethyl-3,6-dithiol-1,8-octanedithiol(MDO)and DVB as raw materials.The MDO-DVB system exhibited excellent storage stability in both high temperature and normal temperature storage environments.Besides,the MDO-DVB system also has good photopolymerization reaction activity,in which the DD1 system can be completely converted within 530 s.The MDO-DVB adhesive has excellent bonding strengths of 2.1 MPa,1.9 MPa and 1.7 MPa on polar glass sheets,respectively,according to the bonding method in this research.Meanwhile,MDO-DVB polymer has excellent physical and optical properties,including DD1 with an optical transmittance of 94% and a film refractive index of 1.613;MDO-DVB adhesive has low swelling properties varieties of solvent environments,which is necessary for the application of the material in liquid environments,and these advantages provide new ideas and perspectives for bonding in optical aspects.