Atom Transfer Radical Polymerization Of Methacrylates Mediated By Iron(Ⅲ) Catalyst

In this thesis, atom transfer radical polymerizations (ATRPs) of oil-soluble monomer methyl methacrylate (MMA) and water-soluble monomer poly(ethylene glycol) monomethyl ether methacrylate (PEGMA) were mediated by different iron(Ⅲ) catalyst systems, respectively. The work can be summarized as follows:(1)Atom transfer radical polymerization with activators generated by electron transfer (AGET ATRP) of MMA using a novel bimetallic catalyst system based on FeCl3·6H2O/CuCl, using tris(3,6-dioxaheptyl)amine (TDA-1) or triphenylphosphine (PPh3) as a ligand and ethyl2-bromoisobutyrate (EBiB) as an initiator, was carried out in bulk in the presence/absence of oxygen (air) at90℃for the first time. The kinetics of the polymerizations was studied. At the same time, different reference experiments for the mono-metallic catalyst system were also investigated. By comparison to these mono-metallic catalyst systems, both the polymerization rate and controllability over molecular weight and molecular weight distribution were enhanced for the bimetallic catalyst system (i.e., a monomer conversion of90%was obtained in2hours of reaction time). The polymerization kinetics showed the features of "living"/controlled radical polymerization. For example, Mn,GPC values of the resultant polymers with narrow molecular weight distribution increased linearly with monomer conversion. In general, CuCl may not only act as a reducing agent but also a co-catalyst.(2) Atom transfer radical polymerizations of PEGMA using EBiB or2-bromobenzeneacetic acid methyl ester (EBPA) as an initiator in bulk with low-toxic iron catalyst system, including iron chloride hexahydrate (FeCl3·6H2O) and triphenylphosphine (PPh3), were carried out successfully. Effect of polymerization temperature and catalyst concentration on the polymerization of PEGMA was investigated. The polymerization kinetics showed the features of "living"/controlled radical polymerization. For example, Mn,GPCc values of the resultant polymers with narrow molecular weight distribution increased linearly with monomer conversion. A faster polymerization of PEGMA could be obtained in the presence of a reducing agent Fe(0) wire or ascorbic acid. For example, in the case of Fe(0) wire as the reducing agent, a monomer conversion of80%was obtained in80min of reaction time at90℃.(3) Living radical polymerizations of PEGMA in the presence of EBiB and2-cyanoprop-2-yll-dithionaphthalate (CPDN) were carried out. CPDN can act as a pseudo-halogen or a chain transfer agent in the polymerization process. Effect of polymerization temperature and the concentration of CPDN on the polymerization of PEGMA was investigated. Besides, the introduction of CPDN can result in controlled radical polymerization of PEGMA at lower temperature (50℃,30℃). The polymerization kinetics showed the features of "living"/controlled radical polymerization. For example, Mn,GPC values of the resultant polymers with narrow molecular weight distribution increased linearly with monomer conversion. In addition, the polymerization of PEGMA using CPDN as initiator was well-controlled in the absence of EBiB.