Study Of Self-coordination Atom Transfer Radical Polymerization

Atom Transfer Radical Polymerization (ATRP) is one of the most widely used method for controlled polymerization in labs. The metal/ligand complex plays the key role in catalyzing the controlled polymerization, and thus it is of great importance to study and develop novel catalyst systems.Poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA), poly(2-(dimethylamino) ethyl acrylate) (PDMAEA), poly(2-(diethylamino)ethyl methacrylate) (PDEAEMA) are all very important cationic polymers and have a great many of applications. However, the ligands used to controlled synthesize them by ATRP are either highly cost or deeply dependent on laboratory synthesis. For example, the most widely used ligand for ATRP of DMAEMA is HMTETA, which is quite expensive. For DMAEA, HMTETA cannot even catalyze it to perform ATRP. Only ligands with much higher catalyzing ability can satisfy this goal, but such liands are often greatly dependent on laboratory synthesis.In lab we found DMAEMA, DMAEA and DEAEMA can perfom ATRP without ligands added in the reation system, and we called this as"self-coordination ATRP". By self-coordination ATRP well controlled Poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) with molecular weight of about 10000, molecular weight distribution of around 1.2 was successfully synthesized. Kenetic study verified the"live"property of this polymerization peocess. What's more, by the similar method we achieved the controlled polymerization of 2-(dimethylamino) ethyl acrylate (DMAEA) and 2-(diethylamino)ethyl methacrylate (DEAEMA). The"live"property of polymerization process of DMAEA at three different temperatures was also verifed.Next the mechanism of self-coordination ATRP was studied. The electron spin resonance (ESR) spectrums demonstrated the existence of Cu(II) and stable radicals during the polymerization process. With the help of theoretical calculation we proposed the stable complex structure and coordination mechanism of Cu(I)/DMAEMA. We gained the bond length and angle about the complex structure. Additionally, we compared the coordination activity energy of Cu(I)/DMAEMA with HMTETA/Cu(I), and applied XAFS to verify related conclusions.Using CuBr/DMAEA,CuBr/DMAEMAå’ŒCuBr/DEAEMA three coordination systems we all successfully synthesized well controlled poly(methyl methacrylate) (PMMA) homopolymers by ATRP. Its molecular weight distribution can be within 1.2~1.4. Each of the polymerization system was confirmed as controllable by dynamic tracing of the polymerization process.