Abstract
Two crystal phases of poly(L-lactide) and that of the racemate of poly(L-lactide) and poly(D-lactide) can be grown epitaxially on one and the same crystalline substrate, hexamethylbenzene (HMB), which had been shown by Zwiers et al. to form a eutectic with these polymers. The stable α-crystal modification of the optically active polymer, based on a 103 helix conformation (for PDLA; 107 for PLLA), is obtained for Tc near 155 °C. A new crystal modification is produced by epitaxial crystallization at slightly lower Tc (≈140 °C). The crystal structure of this new form is established by electron diffraction and packing energy analysis. Two antiparallel helices are packed in an orthorhombic unit-cell of parameters a = 9.95 angstroms, b = 6.25 angstroms and c = 8.8 angstroms. The racemate of poly(L-lactide) and poly(D-lactide) also crystallize epitaxially (at ≈165 °C) on HMB, which appears to be a very versatile substrate.
Original language | English |
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Pages (from-to) | 8909-8919 |
Number of pages | 11 |
Journal | polymer |
Volume | 41 |
Issue number | 25 |
DOIs | |
Publication status | Published - Sept 8 2000 |
Externally published | Yes |
Keywords
- Crystal structure
- Epitaxy
- Polylactide
ASJC Scopus subject areas
- Organic Chemistry
- Polymers and Plastics
- Materials Chemistry