Novel Living Radical Polymerization System And Its Application

Organotellurium compounds mediated living radical polymerization (TERP) is one of the most robust tools of living free radical polymerizations (LRP). However, synthesis and purification of organotellurium compounds are time-consuming and to be operated in an inert atmosphere due to their extremely sensitive to trace oxygen. In this article, a simple process of TERP, operating in open air, has been reported. It has demonstrated that the crude organotellurium compound, ethyl2-phenyltellanyl-2-methylpropionate, could mediate2,2’-azobis (isobutyronitrile) initiated styrene (St) and butyl acrylate (BA) polymerization as an LRP system. For the bulk and solution polymerization of St and the solution polymerization of BA, the molecular weights of produced polymers increased linearly with the monomer conversions. During the same time, the molecular weight distributions kept between1.2-1.5. With the sequential monomer addition technique, a clean diblock polymer of PS-b-PBA was also obtained.A novel visible light induced Ir (ppy)3catalyzed polymerization was used to perform the polymerization of alkynyl monomers. Propargyl methacrylate was used as model monomer, the polymerization was performed free of crosslinking behavior. The molecular weights of produced polymers increased linearly with the monomer conversions. During the same time, the molecular weight distributions kept between1.2-1.5. The alykne unit on the polymer product was kept intact after the polymerization.A novel visible light mediated polymer surface grafting polymerization and post polymerization thio-yne click chemistry process with the sole photoredox catalyst tris-(2-phenylpyridine)iridium (Ir(ppy)3) was developed. Surface initiated photoredox catalyst controlled radical polymerization (SI-PRCRP) with different monomers, such as methyl methacrylate (MMA), propargyl methacrylate (PMA) and trifluoroethyl methacryalte (TFEMA) was investigated. The livingness of SI-PRCRP was demonstrated by the linear increasing of the graft yield (GY, weight of polymer brushes grafted on the substrate surface per square centimeter) with the light irradiation time and the block grafting polymerization. Then, the propargyl groups of the PPMA grafting chains were reacted with pentaerythritoltetra-(3-mercaptopropionate)(PETMP) via thiol-yne click mechanism in order to introduce thiol groups on the LDPE surfaces. The FTIR and XPS spectra revealed the successful introduction of the grafting chains and thiol groups by click chemistry. The existence and reactivity of thiol groups immobilized on the LDPE-g-PPMA were further demonstrated by the thiol-ene click chemistry with N-(1-pyrenyl) maleimide. In summary, this method offers a versatile platform for introducing high concentration of desired functional groups onto the surface of polymeric materials.