Self-healing copolymers via van der Waals interactions
November 10-14, 2019
Materials with build-in responsive components are outstanding candidates for the development of sustainable technologies. Last decade efforts have primarily focused in incorporating supramolecular chemistry and reversible covalent bonding in the development of self-healing polymers. This lecture will outline recent advances in self-healing polymers, with the primary focus on the recent advances in the development of commodity self-healable polymers. Inspired by plants, self-healing can be achieved by incorporating viscoelastic responses to their microstructures during their formation, thus enabling deformation upon mechanical damage to close a wound. This can be achieved by introducing multiphase-separated polymers composed of polycaprolactone, butanediol, and hexamethylene diisocyanate precursors copolymerized into a self-healing polymer.(1) The presence of micro-phase separated fibrous morphologies facilitate repeatable self-healing due to stable interfacial regions between the hard and soft segments of the copolymer, thus enabling of storage of entropic energy upon mechanical damage to be recovered during self-healing. This talk will provide the framework of van der Waals interactions in acrylic-based copolymers able to self-heal upon mechanical damage.(2) This behavior occurs when the monomer molar ratios are within a relatively narrow compositional range, forming reversible ‘key-and-lock’ interactions with preferentially alternating copolymer topologies. The unique self-healing behavior is attributed to favorable inter-chain van der Waals (vdW) forces manifested by the increased cohesive energy densities (CED) forming ‘key-and-lock’ inter-chain junctions, enabling multiple recovery upon mechanical damage without external intervention. The concept of redesigning commodity copolymers without elaborate chemical modifications will facilitate a platform for many technological opportunities and the development of new generations of sustainable copolymers with controlled chain topologies that survive repetitive damage-repair cycles.
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Marek Urban and Siyang Wang, "Self-healing copolymers via van der Waals interactions" in "Composites at Lake Louise 2019", John Kieffer, University of Michigan, USA Erik Spoeke, Sandia National Laboratories, USA Meisha Shofner, Georgia Institution of Technology, USA Eds, ECI Symposium Series, (2019). https://dc.engconfintl.org/composites_all_2019/59