Title: Hydrogen-Bonding Bottlebrush Networks: Self-Healing Materials from Super-Soft to Stiff

Abstract

The impact of polymer architecture on network dynamics and self-healing is presented using bottlebrushes containing side chains that are end-functionalized with 2-ureido-4[1H]-pyrimidinone (UPy). The synthesis of these materials is straightforward through a three-step process: (1) synthesizing rubbery poly(4-methylcaprolactone) macromonomers (p4MCL–OH) with a norbornene-based initiator, (2) functionalizing the terminal hydroxyl group with UPy–isocyanate (p4MCL–UPy), and (3) statistically copolymerizing p4MCL–OH and p4MCL–UPy via ring-opening metathesis polymerization (ROMP) to form hydrogen-bonding bottlebrushes having a fraction (p) of side chains functionalized with UPy. Attaching UPy to the free end of bottlebrush side chains dilutes the impact of friction from complementary UPy interactions on segmental dynamics, leading to a much weaker dependence of the glass-transition temperature (T_g) on p than observed in linear analogues, while the activation energy to dissociate UPy–UPy bonds (41–47 kJ/mol) remains mostly unchanged. Longer side chains result in a competition between reducing T_g and inducing entanglements that influence hydrogen-bonded network dynamics. Increasing the backbone length extends the sticky Rouse region without affecting the network modulus (G_x) or UPy–UPy dissociation time (τ_s). Gx scales linearly with p and ranges from 27 kPa to 1.6 MPa, while τs remains nearly constant in contrast to linear telechelic ionomers, implying a similar self-healability across bottlebrushmore » networks containing different amounts of UPy. Furthermore, these stretchable networks with p ≤ 0.25 undergo self-healing upon repeated rupture and melt pressing at ≤100 °C while retaining similar tensile properties. In summary, decorating bottlebrush polymers with hydrogen bonds creates opportunities to independently manipulate associative network dynamics and mechanical moduli.« less

Authors:

Xie, Renxuan ^[1]; Lapkriengkri, Intanon ^[1]; Pramanik, Nabendu B. ^[1]; Mukherjee, Sanjoy  ^[1];

• Search DOE PAGES for author "Mukherjee, Sanjoy"
• Search DOE PAGES for ORCID "0000-0001-6810-9502"

Blankenship, Jacob R. ^[1]; Albanese, Kaitlin ^[1]; Wang, Hengbin ^[1]; Chabinyc, Michael L.  ^[1];

• Search DOE PAGES for author "Chabinyc, Michael L."
• Search DOE PAGES for ORCID "0000-0003-4641-3508"

Bates, Christopher M.  ^[1]

• Search DOE PAGES for author "Bates, Christopher M."
• Search DOE PAGES for ORCID "0000-0002-1598-794X"

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+ Show Author Affiliations

1. Univ. of California, Santa Barbara, CA (United States)

Publication Date:

Mon Nov 28 00:00:00 EST 2022

Research Org.:

Univ. of California, Santa Barbara, CA (United States)

Sponsoring Org.:

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

OSTI Identifier:

1971664

Grant/Contract Number:  

SC0019001

Resource Type:

Accepted Manuscript

Journal Name:

Macromolecules

Additional Journal Information:

Journal Volume: 55; Journal Issue: 23; Journal ID: ISSN 0024-9297

Publisher:

American Chemical Society

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; Dissociation; Functionalization; Noncovalent interactions; Polymers; Self healing materials