A Model Semi-Crystalline Polymer With a Strictly Monodisperse Distribution of Lamellar Thickness.
Abstract
We have succeeded in synthesizing a model polymer which, by chemical design of the chains, is forced to crystallize into crystals of identical thickness. This goal was reached with a polyester of formula (-O(CH_2)_44O(CO)X(CO)-)_m, where X is a straight trimethylene unit bearing a pendent propyl group on the central carbon atom. This polymer adopts the orthorhombic packing of n-alkanes, with rejection of the pendent propyl groups outside the crystals, and electron-rich ester functions decorating the surfaces of the lamellae, which allows an unambiguous determination of lamellar thickness by small-angle X-ray scattering. For all crystallization temperatures investigated, the polymer was found to crystallize in lamellae of strictly 5.8 nm (+/-0.1 nm), in good agreement with the computed extended length of the long alkane sequence. Although all lamellae are strictly of identical thickness, they crystallize and melt at different temperatures (over 10-15^oC), giving rise to multiple melting and crystallization peaks.
- Publication:
-
APS March Meeting Abstracts
- Pub Date:
- March 2001
- Bibcode:
- 2001APS..MARQ18011J