Linear rod-coil multiblock oligomers with a repeating unit-dependent supramolecular organization

Citation
M. Lee et al., Linear rod-coil multiblock oligomers with a repeating unit-dependent supramolecular organization, MACROMOLEC, 34(6), 2001, pp. 1987-1995
Citations number
31
Categorie Soggetti
Organic Chemistry/Polymer Science
Journal title
MACROMOLECULES
ISSN journal
00249297 → ACNP
Volume
34
Issue
6
Year of publication
2001
Pages
1987 - 1995
Database
ISI
SICI code
0024-9297(20010313)34:6<1987:LRMOWA>2.0.ZU;2-S
Abstract
A series of linear rod-coil multiblock oligomers of the (rod-coil)(n) type (n = 1, 2, 3, 13) consisting of a rigid rod segment made up of three biphen yls connected though methylene ether linkages and a poly(propylene oxide) w ith degree of polymerization of 13 as a coil segment were prepared, and the ir thermal behavior and supramolecular organization in the solid and melt s tates were investigated. In opposition to the behavior of conventional olig omers, transition temperatures of these multiblock oligomers associated wit h both crystalline melting and isotropization decrease With increasing the number of repeating units (n). Small- and wide-angle X-ray diffraction inve stigations were carried out to elucidate the details of supramolecular stru cture. All of the oligomers were observed to be self-organized into ordered supramolecular structures that differ significantly on variation of the nu mber of repeating units. The (rod-coil)(1) shows a lamellar crystalline and a bicontinuous cubic liquid crystalline structures. In contrast, the (rod- eoil)(2) shows a 2-D rectangular crystalline and a tetragonal columnar liqu id crystalline structures, while the (rod-coil)(3) and the (rod-coil)(13) d isplay a hexagonal columnar structure in both their solid and melt states. These results demonstrate that systematic variation of the number of repeat ing units in the rod-coil multiblock oligomers can provide a strategy to re gulate the supramolecular structure, from 1-dimensional lamellar, a-dimensi onal rectangular to 2-dimensional hexagonal structures in the solid state a nd from bicontinuous cubic, tetragonal columnar to hexagonal columnar in th e melt state.