Prepared Structure Controllable Polymer Emulsion By Amphiphilic ATRP Initiator

In recent years, atom transfer radical polymerization (ATRP) has attracted much interest and been widely studied. As one of the most important living/controlled radical polymerization, ATRP has many advantages such as controllable polymer molecular weight, narrow molecular weight distribution, designable molecular structures and so on. Moreover, ATRP can be conducted in various reaction systems such as bulk, solution, emulsion and suspension. But with the enhancing awareness of environment protection, ATRP emulsion polymerization with water as dispersing media is more appreciated by people. And this technology can prepare security environmental protection polymer emulsion which present controlled molecular weight and narrow polydispersity. However, direct ATRP reactions catalyzed by Cu(I) or other low-valent metal ions are sensitive to air, and low-valent metal ions are easily oxidized, sometimes pretreatment of Cu(I)X (X = Cl, Br) for removing possible Cu(II)X impurity is required before the reactions. This problem has been solved by activator generated by electron transfer (AGET) ATRP which applies high-valent metal ions together with appropriate reducing agents, and has overcome the disadvantages of direct ATRP. Therefore, AGET ATRP is more suitable for aqueous phase emulsion polymerization by contrast.In common emulsion polymerizations, however, conventional small molecular emulsifiers must be added to stabilize the reaction system. These small molecular emulsifiers will stay in the final polymers, causing negative effects on the electrical, optical, surface, water resistance of the polymer products. Therefore, in order to avoid these drawback, using reactive surfactants, amphiphilic macro-emulsifiers, and surface-active ATRP initiators in emulsion systems to realize ATRP emulsifier-free emulsion polymerizations become more important.In this thesis, we have first designed and synthesized a anionic surface-active ATRP initiator, and then applied it into emulsion polymerization. Use the ATRP initiator, surfactant-free emulsion polymerizations of some kinds of monomer were implementation under AGET ATRP conditions, and prepared successfully well-controlled polymer emulsion. The main content and achievement of this thesis are as follows: In chapter 2, the novel anionic surface-active ATRP initiator disodium 4-(10-(2-bromo-2-methylpropanoyloxy)decyloxy)-4-oxo-2-sulfonatobutanoate were synthesized efficiently in three steps. The controlled radical emulsion polymerizations of MMA were realized without any added surfactants under AGET ATRP conditions, in which the amphiphilic initiator functioned as both an ATRP initiator and a latex stabilizer.In chapter 3, three fluorinated polymers PTFEMA,PHFBMA,PDFHMA have been prepared successfully in emulsion system using the surface-active ATRP initiator. But it needs to be pointed out that nonionic surfactant OP-10 were required to form synergistic stabilizers with the ATRP initiator during polymerization process because of high hydrophobicity of fluoro monomers. The experimental results demonstrated that the polymerization process of fluoro monomers also has living/controlled characteristics, and the expected molecular weight, narrow molecular weight polydispersity polymer emulsion were obtained. Moreover, the results of contact angle determination indicated that the three fluorinated polymers were all reveal low surface energy.In chapter 4, by employing fluoro monomers and styrene as reactants, AB type block fluorinated copolymers with well-defined structures were prepared in"one pot"by using the ATRP initiator and OP-10 under AGET ATRP in emulsion conditions. Kinetic studies of the emulsion polymerization of PTFEMA-b-PS demonstrated that the polymerization process of two monomers were all have living/controlled characteristics. Surface studies and water absorption determination indicated that the fluorinated block copolymers reveal lower surface energy and stronger hydrophobic property compared with those non-fluorinated polymers, which has promising applications as low surface energy materials and waterproofing coatings.