A solid-state 13C-NMR study of the mesophases of PEIM-9 (poly(4,4′-phthaloimidobenzoylnonamethylene-oxycarbonyl))

✍ Scribed by Jinlong Cheng,; Wei Chen; Ricardo Pardey; Stephen Z. D. Cheng; Bernhard Wunderlich

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 279 KB
• Volume: 10
• Category: Article
• ISSN: 1042-7147
• DOI: 10.1002/(sici)1099-1581(199908)10:8<501::aid-pat902>3.0.co;2-2

✦ Synopsis

On cooling from the melt, poly(4,4'-phthaloimidobenzoylnonamethyleneoxycarbonyl) (PEIM-9) forms a monotropic, smectic liquid crystal phase (T i = 369.2 K). The main driving force for this mesophase formation is the attainment of nanophase separation of the mobile nonamethylene spacer from the geometrically rigid, but irregular, phthaloimidobenzoyl group, coupled with partial conformational ordering of the CH 2 groups (about 20% of the CH 2 groups attain trans-conformations). It is shown by nuclear magnetic resonance that PEIM-9 consists at room temperature of two motionally distinguishable components. One is the liquid crystal that remains mobile to its glass transition temperature (T g % 323 K), the other a more rigid crystal with a large degree of conformational disorder. In this crystal phase (T m % 415 K) the conformationally disordered nonamethylene spacer has a similar amount of disorder than in the liquid crystal phase and the phthaloimidobenzoyl group is also not fully ordered. Even after long-term annealing, all molecules remain conformationally disordered, but T m increases to about % 437 K.