New Types of Stereocomplexes of Steroregular Poymethacrylates

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Syndiotactic (st-) polymers of methacry lates with promary and secondary ester groups, prepared by the syndiotactic-specific libing polymerization with t-C_4H_9Li/R_3Al, were found to form stereocomplexes with isotactic (it-) PMMA by annealing in the solid state or by mixing in certain solvents such as acetone and toluene. Melting points of the complexes depend on the structure of the ester group and can be changed in a side range of temperature, st-Phlymers of tertiary esters did not form the complex. Effects of anneal conditions, molecular weight , and tacticity on the melting point of the complex were studied in some detail for the combinationof st-poly(benzyl methacrylate0 and it-PMMA.st-Random copolymers of MMA with several alkyl methacrylates also formed stereocomplexes with it-PMPMA, whose nelting point could be changed continuously by changing the composition in a certain tange of temperatuer. st-Block copolymers of PMMA and poly(benzyl methacry-late) formed stereocomplexes with it-Pmma which showed two melting points as far as the block lengths are long enough for the two thpes of the complexes to form independently. Stereoblock PMMA, it-PMMA-block-st-PMMA, and stereoblock copolymer, it-PMMA-block-st-poly(butyl methacrylate), were found to form stereocomplexes more easily than the corresponding mixtures. PMMA graft polymers in which the stereogragularity of the main chain and side chains are opposite, ie. isotactic and syndiotactic, were also found to form stereocomplex. Triblock copolymers with a flexible polyisobuty lane (PIB) meddle segment and stereoregular PMMA outer blocks formed stereocomplex with PMMA.The blend comprised amorphous region (PIB) and crystalline region (stereocomplex), and si expected to exhibit elastomeric propeties under ballanced composition of two types of segments.