The Living Feature of the ATRP Macroinitiators in Different Catalytic Systems

Atom transfer radical polymerization (ATRP) has achieved widespread use in living polymerization. However, until now there has been little report that macroinitiators initiate polymerization in different catalytic systems. The preparation of bromine-terminated polymethyl methacrylate (PMMA-Br) and chlorine-terminated PMMA (PMMA-Cl) were carried out via reverse atom transfer radical polymerization (RATRP). The PMMA with halogen termination and narrow polydispersity (Mn = 12,000-15,000 g/mol, Mw/Mn = 1.1-1.2) were used as macroinitiators. The block copolymer of polymethyl methacrylate and polyacrylonitrile (PMMA-b-PAN) was prepared in different catalytic systems through normal ATRP. The analyses of the H-1 NMR showed that the PMMA prepared by RATRP were end-functionalized by halogen atoms, demonstrated the activities of the PMMA macroinitiators. The molecular weight and polydispersity index (PDI) of the polymers were analyzed using gel permeation chromatography (GPC). The results indicated that the block polymers that the molecular weight of the block copolymer after chain extension has increased significantly and the molecular weight distribution is narrow (Mn = 17,000-25,000 g/mol, Mw/Mn = 1.1-1.3). The kinetics of these polymerization processes were studied as a function of monomers to the macroinitiator molar ratio. It was found that the polymerizations in different catalytic systems coincidence first-order kinetics with respect to monomers. [GRAPHICS] .

Automated summary

This study successfully synthesized PMMAs with halogen termination as macroinitiators through RATRP, which showed narrow molecular weight distribution and good activity. These PMMA macroinitiators were able to initiate the synthesis of PMMA-b-PAN block copolymers in different catalytic systems, resulting in a significant increase in molecular weight. The polymerizations in different catalytic systems followed first-order kinetics with respect to monomers.