Title: Bottlebrush Block Polymers: Quantitative Theory and Experiments

Abstract

The self-assembly of bottlebrush block polymers into a lamellar phase was investigated using a combination of experiment and self-consistent field theory (SCFT). Nine diblock bottlebrush polymers were synthesized with atactic polypropylene side chains (block A) and polystyrene side chains (block B) attached to poly(norbornene) backbones of various contour lengths, L, and the resulting lamellar structures were analyzed using small-angle X-ray scattering. The scaling of the lamellar period, d0 ~ Lγ, exhibited an increasing exponent from γ ≈ 0.3 at small L to γ ≈ 0.9 at large L. The small exponents occurred for starlike molecules where the size of the side chains is comparable to L, while the larger exponents occurred for the more brushlike molecules where the side chains extend radially outward from the backbone. The bottlebrushes were then modeled using flexible side chains of types A and B attached to a semiflexible backbone with an adjustable persistence length, ξb. The resulting SCFT predictions for d0 showed remarkable quantitative agreement with the experimental data, where ξb was similar to the radius of the bottlebrushes. The theory was then used to examine the joint-distribution functions for the position and orientation of different segments along the backbone. This revealed a bilayermore » arrangement of the bottlebrushes in the lamellar phase, with a high degree of backbone orientation at the A/B interfaces that almost completely vanished near the center of the domains. This finding clearly refutes the prevailing interpretation that the large scaling exponent γ is a result of highly extended backbone conformations.« less

Authors:

Dalsin, Samuel J.; Rions-Maehren, Thomas G.; Beam, Marissa D.; Bates, Frank S.; Hillmyer, Marc A.; Matsen, Mark W. ^[1]

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+ Show Author Affiliations

1. Department of Chemical Engineering, Department of Physics &, Astronomy, Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada

Publication Date:

Mon Oct 12 00:00:00 EDT 2015

Research Org.:

Argonne National Laboratory (ANL), Argonne, IL (United States). Advanced Photon Source (APS); Univ. of Minnesota, Minneapolis, MN (United States)

Sponsoring Org.:

National Science Foundation (NSF); USDOE Office of Science (SC)

OSTI Identifier:

1225404

Alternate Identifier(s):

OSTI ID: 1237744; OSTI ID: 1418569

Grant/Contract Number:  

CHE-1413862; AC02-06CH11357

Resource Type:

Published Article

Journal Name:

ACS Nano

Additional Journal Information:

Journal Name: ACS Nano Journal Volume: 9 Journal Issue: 12; Journal ID: ISSN 1936-0851

Publisher:

American Chemical Society (ACS)

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; bottlebrush; self-assembly; lamellae; block copolymer; self-consistent field theory; interfaces; x-ray scattering; molecules; chemical calculations; polymers