Free Radical Polymerization Of Methacrylates Initiated By N,N-dimethylaniline And Ethy ?-bromophenylacetate Under Visible Light

Visible light-induced radical polymerization has become a hotspot in polymer chemistry in recent yearsbecause of its mild reaction conditions low energy consumption, green environmental and so on. At present, visible light photosensitizers or visible light catalysts are mostly transition metal compounds and heterocyclic or polycyclic organic compounds. These catalysts/initiators also present some challenges in the preparation of large quantities polymers. Therefore, the development of simple and inexpensive visible light-induced radical polymerization new system is still one of the critical issues of polymer chemistry.1. In this paper, N,N-dimethylaniline (DMA) was used as a visible light photoinitiator to initiate methyl methacrylate (MMA) polymerization, but the efficiency of DMA was low. The polymerization rate could be accelerated and the efficiency of DMA could also be improved whenethy a-bromophenylac--etate (EBP) was added in the reactant, but EBP alone couldn't initiate the polymerization. The polymerization rate increased with increasing DMA or EBP, but the number-average molecular (Mn) weights were around 30000 g/mol. Mn was related to solvents. The results showed that Mn was high in highly polar solvent. The rate of polymerization increased first and then decreased with increasing the amount of EBP with DMA as solvent, the polymerization rate was fastest at [EBP]/[MMA]=0.5%. The polymerization could be switched between "on" and "off" in response to visible light immediately.2. The "living" radical polymerization was succeefully achieved at the ratio of [DMA]/[EBP]/[CTP]=5:1:2, when 6-Phenyl-6-thioxo-5-thia-4-c--yano-4-methylhexanoic acid (CTP) added into the system. Mn and monomer conversion had a good linear relationship; the polydispersity index was relatively low (about 1.1). In DMSO, anisole and DMF these thress solvents,the polymerization reaction was the fastest in DMSO, followed by anisole, and finally in DMF, but the polydispersity index in DMSO was relatively wide.Benzyl methacrylate (BnMA) and 2-hydroxypropyl methacrylate (HPMA)were also achieved "living" radical polymerization under this system.