Title: Bottlebrush-Guided Polymer Crystallization Resulting in Supersoft and Reversibly Moldable Physical Networks

Abstract

The goal of this study is to use ABA triblock copolymers with central bottlebrush B segments and crystalline linear chain A segments to demonstrate the effect of side chains on the formation and mechanical properties of physical networks cross-linked by crystallites. For this purpose, a series of bottlebrush copolymers was synthesized consisting of central amorphous bottlebrush polymer segments with a varying degree of polymerization (DP) of poly(n-butyl acrylate) (PnBA) side chains and linear tail blocks of crystallizable poly(octadecyl acrylate-stat-docosyl acrylate) (poly(ODA-stat-DA)). The materials were generated by sequential atom transfer radical polymerization (ATRP) steps starting with a series of bifunctional macroinitiators followed by the growth of two ODA-stat-DA linear-chain tails and eventually growing poly(nBA) side chains with increasing DPs. Crystallization of the poly(ODA-stat-DA) tails resulted in a series of reversible physical networks with bottlebrush strands bridging crystalline cross-links. They displayed very low moduli of elasticity of the order of 10³–10⁴ Pa. These distinct properties are due to the bottlebrush architecture, wherein densely grafted side chains play a dual role by facilitating disentanglement of the network strands and confining crystallization of the linear-chain tails. This combination leads to physical cross-linking of supersoft networks without percolation of the crystalline phase. The cross-link densitymore » was effectively controlled by the DP of the side chains with respect to the DP of the linear tails (n_A). Furthermore, shorter side chains allowed for crystallization of the linear tails of neighboring bottlebrushes, while steric repulsion between longer side chains hindered the phase separation and crystallization process and prevented network formation.« less

Authors:

Daniel, William F. M. ^[1]; Xie, Guojun ^[2]; Vatankhah Varnoosfaderani, Mohammad ^[1]; Burdynska, Joanna ^[2]; Li, Qiaoxi ^[1]; Nykypanchuk, Dmytro  ^[3];

• Search DOE PAGES for author "Nykypanchuk, Dmytro"
• Search DOE PAGES for ORCID "0000-0002-0461-3467"

Gang, Oleg ^[4]; Matyjaszewski, Krzysztof  ^[2];

• Search DOE PAGES for author "Matyjaszewski, Krzysztof"
• Search DOE PAGES for ORCID "0000-0003-1960-3402"

Sheiko, Sergei S.  ^[1]

• Search DOE PAGES for author "Sheiko, Sergei S."
• Search DOE PAGES for ORCID "0000-0003-3672-1611"

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+ Show Author Affiliations

1. Univ. of North Carolina, Chapel Hill, NC (United States)
2. Carnegie Mellon Univ., Pittsburgh, PA (United States)
3. Brookhaven National Lab. (BNL), Upton, NY (United States)
4. Brookhaven National Lab. (BNL), Upton, NY (United States); Columbia Univ., New York, NY (United States)

Publication Date:

Fri Feb 24 00:00:00 EST 2017

Research Org.:

Brookhaven National Lab. (BNL), Upton, NY (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1438302

Report Number(s):

BNL-205657-2018-JAAM
Journal ID: ISSN 0024-9297

Grant/Contract Number:  

SC0012704

Resource Type:

Accepted Manuscript

Journal Name:

Macromolecules

Additional Journal Information:

Journal Volume: 50; Journal Issue: 5; Journal ID: ISSN 0024-9297

Publisher:

American Chemical Society

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; Bottlebrush polymer; polymer crystallization; physical networks; triblock copolymers