부산대학교 도서관

Stereocomplex formation between uniform isotactic (it-) and uniform syndiotactic (st-) PMMAs in solution was studied by NMR spectroscopy coupled to size-exclusion chromatography (SEC-NMR) and by diffusion-ordered NMR spectroscopy (DOSY). A pair of uniform PMMAs with a chain-length ratio of st-/it-=2 was adopted in the present work because our previous study on the stereocomplexation between it-46mer and st-46mer suggested complexation stoichiometry of st-/it-=2(w/w) [Macromol. Chem. Phys., 202, 3081 (2001)].An equimolar mixture of it-24mer (mm=96%) and st-48mer (rr=98%) in acetone/acetone-d6 (95/5) was allowed to stand at −15°C for 24h, and then subjected to SEC-NMR. An elution peak attributable to stereocomplex was observed between the elution peaks due to non-complexed it-24mer and st-48mer. On the other hand, DOSY analysis of the equimolar mixture showed a unimodal, narrow distribution of self-diffusion coefficient (D). The mean D of the complex was smaller than those of each individual it-24mer and st-48mer.