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Title: Effect of sequence dispersity on morphology of tapered diblock copolymers from molecular dynamics simulations

Tapered diblock copolymers are similar to typical AB diblock copolymers but have an added transition region between the two blocks which changes gradually in composition from pure A to pure B. This tapered region can be varied from 0% (true diblock) to 100% (gradient copolymer) of the polymer length, and this allows some control over the microphase separated domain spacing and other material properties. We perform molecular dynamics simulations of linearly tapered block copolymers with tapers of various lengths, initialized from fluids density functional theory predictions. To investigate the effect of sequence dispersity, we compare systems composed of identical polymers, whose taper has a fixed sequence that most closely approximates a linear gradient, with sequentially disperse polymers, whose sequences are created statistically to yield the appropriate ensemble average linear gradient. Especially at high segregation strength, we find clear differences in polymer conformations and microstructures between these systems. Importantly, the statistical polymers are able to find more favorable conformations given their sequence, for instance, a statistical polymer with a larger fraction of A than the median will tend towards the A lamellae. The conformations of the statistically different polymers can thus be less stretched, and these systems have higher overall density.more » Consequently, the lamellae formed by statistical polymers have smaller domain spacing with sharper interfaces« less
Authors:
 [1] ;  [2] ;  [2] ;  [2]
  1. The Ohio State Univ., Columbus, OH (United States). William G. Lowrie Dept. of Chemical and Biomolecular Engineering; California Inst. of Technology (CalTech), Pasadena, CA (United States). Division of Physics, Mathematics and Astronomy
  2. The Ohio State Univ., Columbus, OH (United States). William G. Lowrie Dept. of Chemical and Biomolecular Engineering
Publication Date:
Grant/Contract Number:
SC0014209; 1454343; SC0014458
Type:
Accepted Manuscript
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 145; Journal Issue: 23; Journal ID: ISSN 0021-9606
Publisher:
American Institute of Physics (AIP)
Research Org:
The Ohio State Univ., Columbus, OH (United States). William G. Lowrie Dept. of Chemical and Biomolecular Engineering
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE
OSTI Identifier:
1465369
Alternate Identifier(s):
OSTI ID: 1336839; OSTI ID: 1468591