Synthesis And Performance Of Hydrophilic Polysiloxane Modified Macromolecular Photoinitiators With Ionic Liquid Character

The water-borne photopolymerization technology has not only the advantages of low energy consumption,fast polymerization rate,and low polymerization temperature as those in traditional photopolymerization technology;but also has been widely acknowledged to exhibit the excellent environmentally friendly property because water replaces harmful monomers as diluents.Photoinitiators play a pivotal role in photopolymerization process,and their characteristics directly affect the photopolymerization rate and other aspects of photopolymerization formulations.However,commercial photoinitiators used for water-borne photopolymerization systems possess undesirable characteristics of poor water solubility,relatively strong odor and volatility,and high migration behavior from cured films.In order to solve these problems,we have designed and synthesized a hydrophilic imidazolium-containing polysiloxane-polyether block macromolecular photoinitiator with new desirable properties involving good water-solubility,low volatility and migration,and excellent thermal stability for water-borne photopolymerization systems,through the combining the advantages of excellent solubility and non-volatility of ionic liquids(ILs)and good chemical/thermal stability and low surface energy of polysiloxanes.The main research contents and conclusions:1.Three hydrophilic polysiloxane-polyether block a-hydroxy alkylphenones macromolecular photoinitiators with ionic liquid character([Si-En-2959Im][TsO](n = 1,3,5)were designed and synthesized as a novel green photoinitiator based on polysiloxane,traditional photoinitiator 2-hydroxy-1-[4-(2-hydroxy ethoxy)phenyl]-2-methyl propan-1-one(2959)and imidazolium.Their structures were confirmed through'H-NMR,29Si-NMR and FTIR.The water-solubility,volatility,photodegradation mechanism,migration of photolysis fragments and antibacterial properties of[Si-En-2959Im][TsO]were investigated by TGA,UV,ESR,FTIR and LC-MS.The research results showed that[Si-En-2959Im][TsO]had good solubility in water and good thermal properties and low saturated vapor pressure compared to Irgacure 2959.The[Si-En-2959Im][TsO]not only can effectively initiate photopolymerization,but also can effectively hinder the migration of photolysis fragments from the cured material.In addition,the UV cured films prepared using[Si-En-2959Im][TsO]possess effective antibacterial activity,demonstrating that[Si-En-2959Im-A][TsO]are effective antibacterial agent.The[Si-En-2959Im][TsO]should have potential applications in preparing more environmentally friendly and antibacterial materials.2.To investigate the effect of the introduction of acrylate double bond into the hydrophilic polysiloxane-polyether block a-hydroxy alkylphenones macromolecular photoinitiators on the performances of the photoinitiators,three water-soluble polymerizable polysiloxane-polyether block a-hydroxy alkylphenones macromolecular photoinitiators with ionic liquid character([Si-En-2959Im-A][TsO](n = 1,3,5)were designed and synthesized as novel environmentally friendly photoinitiators based on imidazolium,traditional photoinitiator 2-hydroxy-1-[4-(2-hydroxy ethoxy)phenyl]-2-methyl propan-1-one(Irgacure 2959),and polysiloxane.Their structures were confirmed through 1H-NMR,29Si-NMR and FTIR.The water-solubility,volatility,photodegradation mechanism,migration of photolysis fragments and antibacterial properties of[Si-En-2959Im-A][TsO]were investigated by TGA,UV,ESR,FTIR and LC-MS.In addition,the effect of the introduction of acrylate double bond on the performance of the photoinitiators was investigated by comparing with[Si-En-2959Im][TsO].The research results showed that[Si-En-2959Im-A][TsO]had good solubility in water and thermal properties and low saturated vapor pressure compared to Irgacure 2959.The introduction of double bonds did not affect the water solubility of[Si-En-2959Im-A][TsO],but their thermal stability and low volatility slightly were increased.The[Si-En-2959Im-A][TsO]not only can effectively initiate photopolymerization,but also can effectively hinder the migration of photolysis fragments from the cured material.In addition,the UV cured films prepared using[Si-En-2959Im-A][TsO possess effective antibacterial activity,demonstrating that[Si-En-2959Im-A][TsO]are effective antibacterial agent.Cured films initiated by[Si-En-2959Im-A][TsO]have good thermostability compared with that by 2959.The[Si-En-2959Im-A][TsO]should have potential applications in preparing more environmentally friendly and antibacterial materials.3.In order to study the effects of different anion structures on the water solubility and photoinitiating performances of polysiloxane block a-hydroxy alkylphenones macromolecular photoinitiators with ionic liquid character,five polysiloxane block macromolecular photoinitiators containing different anion structures with ionic liquid character.([Si-2959Im][X](X = Br-,Ph4B-,TsO-,NO3-,CF3COO-))were designed and synthesized as novel environmentally photoinitiators based on imidazolium,Irgacure 2959 and polysiloxane.Their structures were confirmed through 1H-NMR,29Si-NMR and FTIR.The water-solubility,volatility,UV absorption,photodegradation mechanism,photoinitiating property and migration of photolysis fragments of[Si-2959Im][X]were investigated by TGA,UV,ESR,FTIR and LC-MS.Mechanical properties of the cured films initiated by[Si-2959Im][X]were investigated.The research results showed that the structure of anion can significantly affect the water-solubility of the photoinitiators.The order of water-solubility is Ph4B-<Br-<TsO-<NO3-<CF3COO-.The photoinitiators with different anions have good thermal stability and low vapor pressure.In addition,the structure of anion affects the thermal stability and saturated vapor pressure of ionic liquid photoinitiators.The order of thermal stability is CF3COO-<NO3-<Ph4B-<Br-<TsO-,and the order of saturated vapor pressure is CF3COO-<NO3-<Ph4B-<Br-<TsO-.The electron-donating ability of different anions influence the molar extinction coefficient of[Si-2959Im][X],and the order is Ph4B->Br->NO3->TsO->CF3COO-.The[Si-2959Im][X]not only can effectively initiate photopolymerization,but also can effectively hinder the migration of photolysis fragments from the cured material.