Strained Bottlebrushes in Super-Soft Physical Networks

Charles Clair; Abdelaziz Lallam; Martin Rosenthal; Michael Sztucki; Mohammad Vatankhah-Varnosfaderani; Andrew N Keith; Yidan Cong; Heyi Liang; Andrey V Dobrynin; Sergei S Sheiko; Dimitri A Ivanov

doi:10.1021/acsmacrolett.9b00106

Strained Bottlebrushes in Super-Soft Physical Networks

ACS Macro Lett. 2019 May 21;8(5):530-534. doi: 10.1021/acsmacrolett.9b00106. Epub 2019 Apr 23.

Authors

Affiliations

¹ Laboratoire de Physique et Mécanique Textiles, F-68093 Mulhouse Cedex, France.
² European Synchrotron Radiation Facility, F-38043 Grenoble, France.
³ Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States.
⁴ Department of Polymer Science, University of Akron, Akron, Ohio 44325-3909, United States.
⁵ Institute of Macromolecular Compounds of the Russian Academy of Sciences, St. Petersburg, 199004, Russian Federation.
⁶ Institut de Sciences des Matériaux de Mulhouse-IS2M, CNRS UMR 7361, F-68057 Mulhouse, France.
⁷ Lomonosov Moscow State University, Faculty of Fundamental Physical and Chemical Engineering, Leninskie Gory 1/51, 119991 Moscow, Russian Federation.
⁸ Moscow Institute of Physics and Technology (State University), Institutskiy per. 9, Dolgoprudny, Russian Federation.
⁹ Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, Moscow region, 142432, Russian Federation.

PMID: 35619373
DOI: 10.1021/acsmacrolett.9b00106

Abstract

ABA triblock copolymers composed of a poly(dimethylsiloxane) (PDMS) bottlebrush central block and linear poly(methyl methacrylate) (PMMA) terminal blocks self-assemble into a physical network of PDMS bottlebrush strands connected by PMMA spherical domains. A combination of small- and ultrasmall-angle X-ray scattering techniques was used to concurrently examine dimensions of PMMA spherical domains and PDMS bottlebrush strands both in the bulk and at the PMMA-PDMS interface. In agreement with scaling model predictions, the degrees of polymerization of the bottlebrush backbone (n_bb) and PMMA block (n_A) correlate with the measured PMMA domain size and area per molecule at the PMMA-PDMS interface as D_A ∝ (n_bbn_A)^1/3 and S ∝ n_A^2/3n_bb^-1/3, respectively. In the bulk, bottlebrush strands are extended due to steric repulsion between the side chains and unfavorable interactions between the different blocks. At the PMMA-PDMS interface with large curvature, packing constraints require additional bottlebrush backbone extension and alignment of side chains along the backbone in the direction perpendicular to the interface.