Application of oleic acid imidazoline in atom transfer radical polymerization

Reverse atom transfer radical polymerization (RATRP) of styrene (St) and electron transfer for atom transfer radical polymerizationCAGET ATRP) of methyl methacrylate (MMA) were studied using oleic acid imidazoline (OLC) as ligand, the relation of the monomer conversion measured by the weight method and the molecular weight (M _n) and the molecular weight distribution measured by Gel Permeation Chromatography(GPC) were discussed, respectively. The polymeric kinetics and kinetic parameters of RATRP of St and AGET ATRP of MMA were also investigated. The results showed that the RATRP of St could be successfully carried out using OLC as ligand, hydrogen peroxide tert-butyl as initiator and FeCl ₃, CuCl ₂ or NiCl ₃ as catalysts: the polymerization exhibited first order kinetics and the activity could be well-controlled. For the system of TBHP/CuCl ₂/OLC, the rate was fast, the molecular weight distribution was as narrow as 1.29 and the initiation efficiency was high (f=0.89). The AGET ATRP of MMA was also carried out in the presence of ethyl 2-bromopropanoate as initiator and OLC as ligand that served not only as ligand but also as reducing agents and also showed first order kinetics. Well-controlled poly(methyl methacrylate) (PMMA) with low molecular weight distribution (1.24) was prepared in the presence of Cu(II)Cl ₂/OLC. The comparison of the kinetic parameters indicated Apparent Rate Constant (k _app) and Concentration of Propagating Radicals of AGET ATRP of MMA were 4.33 × 10 ^-4 s ^-1 and 4.351 × 10 ^-7 mol/L, respectively, higher than those of RATRP of St.