The diblock copolymer poly（methyl methacrylate）-block-polytetrahydrofuran（PMMA-b-PTHF） was successfully synthesized by means of the coupling reaction of living cationic PTHF+, SbF-6 and living anionic PMMA-, Li+. Lithium chloride, which is frequently used as a ligand in the polymerization of （meth）acrylates, obstructs the coupling reaction between the anionic and the cationic precursors due to the combination of the chlorine anion with the PTHF cation. Thus, the anionic polymerization should be carried out in the absence of LiCl.
Four armed star shaped copolymer of methyl methacrylate(MMA)/ N cyclohexylmaleimide(NCMI) with heat resistance was synthesized by atom transfer radical copolymerization with the CuBr/bpy catalyst in anisole, initiated by tetra(bromomethyl)benzene. A linear plot of ln( 0/) versus reaction time was obtained by using anisole as solvent. In contrast, the use of cyclohexanone as solvent results in that the rate of copolymerization decreases as the reaction proceeds. Using anisole as the solvent in the copolymerization, the molecular weight of the resultant copolymer(measured by triple detection SEC) increased linearly with the increase of conversion, and the molecular weight distributions are narrow. The glass transition temperature of the resultant copolymer was higher than that of the pure PMMA. The synthesized four armed star copolymer was used as macroinitiator for the cationic polymerization of 2 methyl 2 oxazoline to yield star shaped poly(MMA co NCMI)/poly(2 methyl 2 oxazoline) block copolymers. The approximately linear increase of the molecular weight with the increase of reaction time and the low molecular weight distribution demonstrate a controlled chain extension reaction.
Atom transfer radical copolymerization(ATRP) of styrene(St) and N cyclohexylmaleimide(NCMI) with the CuBr/bpy catalyst in anisole, initiated by 1 phenylethyl bromide(1 PEBr) or tetra (bromomethyl)benzene(TBMB), afforded well defined copolymer with predetermined molecular weights and low polydispersities, M w/ M n<1.5. Other monomer pairs such as methyl methacrylate(MMA)/NCMI, St/ N phenylmaleimide, MMA/ N phenylmaleimide were studied, too. The influences of several factors, such as temperature, solvent and monomer’s ratio on the copolymerization with the CuBr/bpy catalyst system were subsequently investigated. The apparent activation energy of St(MMA)and NCMI was deduced from the kinetics figure of different temperatures. Using TBMB as the initiator produced four armed star copolymer. The heat resistance of the resultant copolymer has been improved by increasing the NCMI. [WT5HZ]
