No abstract

No abstract

No abstract

Poly(methyl methacrylate)-6-poly(i eri-butyl acrylate) (PMMA-6-PtBA) copolymers have been successfully synthesized by the sequential anionic polymerization of methyl methacrylate (MMA) and tertbutyl acrylate (tBA) in THF at -78 °C. Although the order of monomer addition makes a difference on the initiation efficiency, it has no significant effect on the final achievement. Monoand bifunctional initiators based on alkali metals can be used. When the initiators are modified by LiCl as a ligand, the polymerization of each block appears to be living, the molecular weight and composition can be predicted, and the molecular weight distribution is narrow. Size exclusion chromatography supports the absence of homo-PtBA in the PtBA-6-PMMA samples. The PtBA blocks can be quantitatively hydrolyzed into polyacid ones as supported by titration and NMR analysis.

Different polystyrene (PS)-poly(tert-butyl acrylate) (PtBuA) block copolymers have been synthesized by first preparing "living" PS using mono-or difunctional initiators, followed by polymerization of tBuA in THF at -78 °C. The chain length of PtBuA blocks can be controlled in a predictable way with a very narrow molecular weight distribution when polystyrene macroanions are modified by LiCl as a ligand. Diand triblock copolymers are obtained essentially free from homopolystyrene as shown by gel permeation chromatography. The phase morphology of a diblock copolymer of about 50/50 molar composition consists of randomly distributed, short alternating lamellae of PS and PtBuA. The PtBuA blocks can be quantitatively hydrolyzed into polyacid blocks as supported by titration, NMR, and IR analysis. Subsequent neutralization of the polyacid block with a variety of bases leads to two-phase copolymers containing an ionomer type of component.