Integration of multiple types of dynamic linkages into one polymer network is challenging and not well understood especially in the design and fabrication of dynamic polymer nanocomposites (DPNs). In this contribution, we present facile methods for synthesizing flexible, healable, conductive, and recyclable thermoresponsive DPNs using three dynamic chemistries playing distinct roles. Dynamic hydrogen bonds account for material flexibility and recycling character. Thiol-Michael exchange accounts for thermoresponsive properties. Diels–Alder reaction leads to covalent bonding between polymer matrix and nanocomposite. Overall, the presence of multiple types of orthogonal dynamic bonds provided a solution to the trade-off between enhanced mechanical performance and material elongation in DPNs. Efficient reinforcement was achieved using <1 wt % multiwalled carbon nanotubes as nanocomposite. Resulting DPNs showed excellent healability with over 3 MPa increase in stress compared to unreinforced materials. Due to multiple responsive dynamic linkages, >90% stress–relaxation was observed with self-healing achieved within 1 h of healing time. Increased mechanical strength, electrical conductivity, and reprocessability were achieved all while maintaining material flexibility and extensibility, hence highlighting the strong promise of these DPNs in the rapidly growing fields of flexible compliant electrodes and strain sensors.
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Carbon nanotube enhanced dynamic polymeric materials through macromolecular engineering
Dynamic covalent Diels–Alder chemistry was combined with multiwalled carbon nanotube (CNT) reinforcement to develop strong, tough and conductive dynamic materials. Unlike other approaches to functionalizing CNTs, this approach uses Diels–Alder bonds between diene pendant groups on the polymer and the CNT surface πσ bonds acting as dienophiles. Experimental and simulation data align with the CNT reinforcement coming from dynamic covalent bonds between the matrix and the CNT surface. The addition of just 0.9 wt% CNTs can lead to an almost 3-fold increase in strength and 6–7 order of magnitude increases in electrical conductivity, and materials with 0.45 wt% CNTs show excellent strength, self-healing and conductivity.
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- Award ID(s):
- 1749730
- NSF-PAR ID:
- 10218009
- Date Published:
- Journal Name:
- Materials Advances
- Volume:
- 1
- Issue:
- 5
- ISSN:
- 2633-5409
- Page Range / eLocation ID:
- 1071 to 1076
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/D0MA00143K
