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Title: Conformational Asymmetry and Quasicrystal Approximants in Linear Diblock Copolymers

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Journal Article: Publisher's Accepted Manuscript
Journal Name:
Physical Review Letters
Additional Journal Information:
Journal Volume: 118; Journal Issue: 20; Related Information: CHORUS Timestamp: 2017-05-16 22:13:51; Journal ID: ISSN 0031-9007
American Physical Society
Country of Publication:
United States

Citation Formats

Schulze, Morgan W., Lewis, Ronald M., Lettow, James H., Hickey, Robert J., Gillard, Timothy M., Hillmyer, Marc A., and Bates, Frank S. Conformational Asymmetry and Quasicrystal Approximants in Linear Diblock Copolymers. United States: N. p., 2017. Web. doi:10.1103/PhysRevLett.118.207801.
Schulze, Morgan W., Lewis, Ronald M., Lettow, James H., Hickey, Robert J., Gillard, Timothy M., Hillmyer, Marc A., & Bates, Frank S. Conformational Asymmetry and Quasicrystal Approximants in Linear Diblock Copolymers. United States. doi:10.1103/PhysRevLett.118.207801.
Schulze, Morgan W., Lewis, Ronald M., Lettow, James H., Hickey, Robert J., Gillard, Timothy M., Hillmyer, Marc A., and Bates, Frank S. Tue . "Conformational Asymmetry and Quasicrystal Approximants in Linear Diblock Copolymers". United States. doi:10.1103/PhysRevLett.118.207801.
title = {Conformational Asymmetry and Quasicrystal Approximants in Linear Diblock Copolymers},
author = {Schulze, Morgan W. and Lewis, Ronald M. and Lettow, James H. and Hickey, Robert J. and Gillard, Timothy M. and Hillmyer, Marc A. and Bates, Frank S.},
abstractNote = {},
doi = {10.1103/PhysRevLett.118.207801},
journal = {Physical Review Letters},
number = 20,
volume = 118,
place = {United States},
year = {Tue May 16 00:00:00 EDT 2017},
month = {Tue May 16 00:00:00 EDT 2017}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1103/PhysRevLett.118.207801

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Cited by: 12works
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  • We use a Landau theory to study the instability of the homogeneous state of a mixture of linear random copolymers and diblock copolymers. Interesting features of the calculated structure factors for different components of the mixture are found, which can be directly compared with scattering experiments with selectively deuterated samples. We also investigate the least stable concentration fluctuations and find four different types of segregation modes at the spinodal depending upon the characteristics of the mixture (e.g., average compositions, statistical correlation lengths and volume fractions). The different segregation modes are also indicative of the kinetic pathways leading to the formationmore » of ordered microstructures. Experiments probing these pathways are suggested. (c) 2000 American Institute of Physics.« less
  • Diblock copolymers with extreme architectural asymmetry, namely dendritic-linear coil molecules, have recently been exploited in the construction of well-defined Langmuir-Blodgett monolayers1 and the chemical alteration of bulk material surfaces via adsorption. Others have studied the assembly of dendritic-linear hybrid blocks in aqueous solution for solute encapsulation. These studies of supramolecular assembly and surface adsorption/assembly exploit the high density of chemical functionality on the periphery of dendritic molecules and the disparate chemical nature inherent in block copolymers for structure formation via self-assembly from solution. To understand the effects of the architectural asymmetry present in dendritic-linear coil block copolymers on supramolecular self-assemblymore » and structure formation, the bulk phase behavior of two series of benzyl ether dendrimer-polystyrene (PS) linear coil diblocks was characterized.« less
  • Double-crystalline diblock copolymers of linear polyethylene (LPE) and hydrogenated polynorbornene (hPN) are synthesized, and their crystallization behavior and morphology are examined using small-angle (SAXS) and wide-angle X-ray scattering (WAXS). In symmetric hPN/LPE diblocks with molecular weights above 50 kg/mol, the hPN block has previously been shown to crystallize first and set the solid-state microstructure. Two-dimensional WAXS on hand-drawn fiber specimens reveals that the LPE crystals formed in confinement stack orthogonally to the hPN crystals. By adjusting total molecular weight, the order of block crystallization may be reversed, even while holding the block length ratio fixed. At a diblock molecular weightmore » of 20 kg/mol, simultaneous time-resolved SAXS/WAXS reveals that the LPE block crystallizes first, even when LPE is the minority component, and restricts hPN to crystallize between the LPE lamellae. The relative orientation of the LPE and hPN crystals in the lower molecular weight diblocks is examined by modeling changes in the SAXS primary peak intensity on cooling two diblocks through the hPN crystal-crystal transition, where hPN densifies as it adopts a rotationally ordered crystal structure. Only a perpendicular stacking of hPN and LPE crystals consistently yields the large reduction in primary SAXS peak intensity observed for both diblocks. Thus, even though the templating block switches from hPN to LPE as the diblock molecular weight is reduced, the orthogonal stacking motif is retained for both high- and low-molecular-weight copolymers.« less
  • Rheological evidence of composition fluctuations in disordered diblock copolymers near the order disorder transition (ODT) has been documented in the literature over the past three decades, characterized by a failure of time–temperature superposition (tTS) to reduce linear dynamic mechanical spectroscopy (DMS) data in the terminal viscoelastic regime to a temperature-independent form. However, for some materials, most notably poly(styrene-b-isoprene) (PS–PI), no signature of these rheological features has been found. We present small-angle X-ray scattering (SAXS) results on symmetric poly(cyclohexylethylene-b-ethylene) (PCHE–PE) diblock copolymers that confirm the presence of fluctuations in the disordered state and DMS measurements that also show no sign ofmore » the features ascribed to composition fluctuations. Assessment of DMS results published on five different diblock copolymer systems leads us to conclude that the effects of composition fluctuations can be masked by highly asymmetric block dynamics, thereby resolving a long-standing disagreement in the literature and reinforcing the importance of mechanical contrast in understanding the dynamics of ordered and disordered block polymers.« less
  • A two-dimensional quasicrystal with fivefold symmetry and two large-unit-cell crystalline approximants in an Al{endash}Co{endash}Ni{endash}Tb alloy, which were observed in previous studies, are suggested to be composed of the same kind of atom cluster. Some characteristics of the atom cluster can be deduced from a high-resolution electron microscopy image of the Al{endash}Co{endash}Ni{endash}Tb quasicrystal when the image is associated to a fivefold aperiodic tiling. By using the cut-and-projection method, a quasiperiodic tiling generated by an irrational projection is proposed as an ideal quasilattice of the Al{endash}Co{endash}Ni{endash}Tb quasicrystal; in the meantime, periodic tilings generated by a rational projection present the lattices of themore » crystalline approximants. {copyright} {ital 1996 Materials Research Society.}« less