PREPARATION OF STEREOREGULAR UNIFORM POLY MER ARCHITECTURES

Stereoregular poly(methyl methacrylate)s (PMMAs) having a functional g roup at their terminating chain-end were prepared by stereospecific li ving polymerization. The resulting enc-functional PMMAs were fractiona ted into uniform polymers by means of supercritical fluid chromatograp hy (SFC). The uniform PMMAs thus obtained were effectively used as bui lding blocks to construct stereoregular uniform polymer architectures, such as stereoblock, star, and comb-like polymers. Stereoblock PMMA w ith uniform block lengths (uniform stereoblock PMMA) was prepared by c oupling reaction between isotactic (it-) and syndiotactic (st-) PMMAs having a hydroxyl end group, followed by GPC or SFC separation. The re sulting uniform stereoblock PMMA was found on the basis of GPC analysi s to form intra- and intermolecularly associated stereocomplexes in ac etone. Uniform isotactic and syndiotactic three-arm star PMMAs were al so prepared by the coupling reaction between PMMA-OHs and 1,3,5-benzen etricarbonyl trichloride. Stereoregularity of the branches was found t o affect the branching effect on the solution viscosity of the star po lymers. Polymerizations of uniform st-and it-PMMA macromonomers were c arried out with radical and anionic initiators. The products were sepa rated by GPC or SFC into uniform oligo(macromonomer) s, whose solution viscosities clearly showed branching effect. Anionic copolymerization of the uniform macromonomers with DPs of prime numbers (25 and 31) ga ve the products consisting of copolymer homologues each of which has a number of monomer units different from the others, and the products c ould be fractionated into each component by means of:SFC. Quantitative analysis of the product distribution by SFC gave information on the r eactivities of macromonomers and propagating anions.