| Abstract: | The glass transition temperature and heat capacity have been determined by differential scanning calorimetry on samples of heterotacticlike monodisperse poly(methyl methacrylate) (PMMA). The nuclear magnetic resonace spectra of these samples reveal that they contain a larger percentage of mr triads (ca. 51%) than atactic polymers and that their microstructure may be predominantly stereoregular because of an abundance of mrrr sequences. We combine our Tg values with data from the literature for PMMAs of other tacticities, in order to analyze the correlation of Tg with tacticity. In this analysis, we consider PMMA as a steric copolymer formed by mm, mr, and rr triads. |
