Dynamic Bottlebrush Polymer Networks: Self-Healing in Super-Soft Materials

Jeffrey L. Self, Caitlin S. Sample, Adam E. Levi, Kexin Li, Renxuan Xie, Javier Read De Alaniz, Christopher M. Bates

Research output: Contribution to journalArticlepeer-review

28 Scopus citations

Abstract

We introduce a design strategy to expand the range of accessible mechanical properties in covalent adaptable networks (CANs) using bottlebrush polymer building blocks. Well-defined bottlebrush polymers with rubbery poly(4-methylcaprolactone) side chains were cross-linked in formulations that include a bislactone and strong Lewis acid (tin ethylhexanoate). The resulting materials exhibit tunable stress-relaxation rates at elevated temperatures (160-180 °C) due to dynamic ester cross-links that undergo transesterification with residual hydroxy groups. Varying the cross-linker loading or bottlebrush backbone degree of polymerization yields predictable low-frequency shear moduli ca. 10-100 kPa, well below values typical of linear polymer CANs (1 MPa). These extensible networks can be stretched to strains as large as 350% before failure and undergo efficient self-healing to recover >85% of their original toughness upon repeated fracture and melt processing. In summary, molecular architecture creates new opportunities to tailor the mechanical properties of CANs in ways that are otherwise difficult to achieve.

Original languageEnglish (US)
Pages (from-to)7567-7573
Number of pages7
JournalJournal of the American Chemical Society
Volume142
Issue number16
DOIs
StatePublished - Apr 22 2020
Externally publishedYes

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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