Synthesis of Poly(n-butyl acrylate) Homopolymers by Activators Generated by Electron Transfer (AGET) ATRP Using FeCl3·6H2O/Succinic Acid Catalyst

Awell-defined poly(n-butyl acrylate) (PBA) homopolymer was prepared by activators generated by electron transfer (AGET) ATRP at 90°C in N,N-dimethylformamide using ferric chloride hexahydrate (FeCl3.6H2O)/succinic acid (SA) as a catalyst and ethyl 2-bromoisobutyrate as an initiator. Ascorbic acid was selected as a reducing agent. The kinetic results showed that a linear increase of molecular weights of polymers with monomer conversion and a relatively narrow polydispersity ( 1.25), when the conversion is beyond 40%, is an indication of a polymerization controlled by AGET ATRP of n-butyl acrylate (nBA). That is to say, (FeCl3.6H2O)/SA catalyst complex is demonstrated to be highly efficient for the AGET ATRP of nBA. The effects of different molar ratios of [FeCl3.6H2O]/[SA] and the concentration of ascorbic acid on polymerization rate were investigated. The maximum polymerization rate was obtained at molar ratio of [FeCl3.6H2O]/[SA] = 1:2 and gave the best control of molecular weight and the distribution of polymer molecular weight. The polymerization reaction rate decreased when the higher or lower molar ratio of [FeCl3.6H2O]/[SA] was employed. The polymerization rate increased with higher content of ascorbic acid. The effects of different solvents on the polymerization were investigated. The experimental results showed that the polymerization rate was faster in polar solvent (such as DMF) than that in non-polar solvent (such as benzene). The obtained polymers had higher molecular weights with narrow distribution of molecular weight in DMF than that in benzene.Moreover, the obtained PBA was used as a macroinitiator in the chain extension experiment via AGET ATRP. The molecular weight of polymer increased after chain extension experiment. The chain extension experiment confirmed the living character of the polymerization system. The resultant PBA was characterized by 1H NMR, FTIR and gel permeation chromatography.