Perforated Layer Structures in Liquid Crystalline Rod-coil Block Copolymers
We report a novel observation of the tetragonal perforated layer structures in a series of rod-coil liquid crystalline block copolymers (BCPs), poly(styrene-block-(2, 5-bis[4-methoxyphenyl]oxycarbonyl)styrene) (PS-b-PMPCS). PMPCS forms rigid rods while PS forms the coil block. Differential scanning calorimetry (DSC), polarized light microscopy (PLM), small-angle X-ray scattering (SAXS), wide-angle X-ray diffraction (WAXD), and transmission electron microscopy (TEM) techniques were used to investigate these rod-coil molecules, and a perforated layer structure was observed at {sup fPMPCS} {approx} 0.37 in relatively low molecular weight (M{sub w}) samples and {approx}0.5 in high M{sub w} PS-b-PMPCS. This substantial phase boundary shift was attributed to the rod-coil nature of the BCP. The perforation obeys a tetragonal instead of hexagonal symmetry. The 'onset' of perforation was also observed in real space in sample PS{sub 272}-b-PMPCS{sub 93} ({sup fPMPCS} {approx} 0.52), in which few PS chains punctuate PMPCS layers. A slight increase in f{sub PS}, by blending with PS homopolymer, led to a dramatic change in the BCP morphology, and uniform tetragonal perforations were observed at {sup fPMPCS} {approx} 0.48.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source
- Sponsoring Organization:
- Doe - Office Of Science
- DOE Contract Number:
- DE-AC02-98CH10886
- OSTI ID:
- 913904
- Report Number(s):
- BNL-78472-2007-JA; JACSAT; TRN: US200804%%116
- Journal Information:
- J. Am. Chem. Soc., Vol. 127, Issue 44; ISSN 0002-7863
- Country of Publication:
- United States
- Language:
- English
Similar Records
Thin Film Self-Assembly of a Silicon-Containing Rod–Coil Liquid Crystalline Block Copolymer
Influence of LC Content on the Phase Structures of Side-Chain Liquid