Self-Healable Thermoplastic Copolymers

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PART 1: NON-TECHNICAL SUMMARYSelf-healing is the capability of a material to recover from physical damage. This research aims at advancing our limited knowledge on the design and development of commodity polymers that exhibit self-healing properties. An ultimate goal is the development of new generation of inexpensive polymeric materials that are capable of autonomous self-healing. The planned research will impact fields of polymer and materials science, polymer engineering and processing, as well as technologically related fields. It is envisioned that existing polymers and devices made out of these materials will last longer while sustaining useful functions. The significance and importance of the proposed research lies in numerous critical applications of low-cost materials in the energy, healthcare, and homeland security sectors, all of which are vital to US global competitiveness. This project will develop scientific protocols on how to design polymeric materials with sustainable and useful functions by imbedded self-healing properties. These studies will involve design and preparation of thermoplastic commodity polymers that are capable of self-healing. Such prepared materials will be tested for mechanical and chemical integrity during damage-repair cycles in the presence and absence of water. The output of the tests will be used to perform computer simulations in an effort to understand underlying processes of self-healing. Through the integration of research and education, a new generation of diversified graduate students who will become productive members of society will be educated. This training will include addressing fundamental scientific questions on how commodity plastics can be equipped with self-healing functions so they become sustainable and minimize waste plastics accumulation. PART 2: TECHNICAL SUMMARYThe goal of the project is to equip commodity copolymers with self-healing properties which will be accomplished by understanding the role of copolymer compositional and structural dependences on self-healing. The proposed studies are organized into two interactive research areas: 1) copolymerization of self-healing methacrylate/acrylate-based fluoro-containing copolymers and 2) elucidating the origin of molecular level processes that govern self-healing in the presence of hydrophobic and hydrophilic environments under hydrostatic pressures. An ultimate scientific objective will be to elucidate the origin and the strength of van der Waals (vdW) interactions on the efficiency of self-healing. To accomplish these objectives a series of commodity monomers with variable monomer molar ratios will be copolymerized. They include but are not be limited to 2,2,2-trifluoroethyl methacrylate (TFEMA), 1,1,1,3,3,3-hexafluoroisopropyl methacrylate (HFIPMA), 2,2,3,3,4,4,4-heptafluorobutyl methacrylate (HFBMA), 2,2,2-trifluoroethyl methacrylate (TFEMA), 1,1,1,3,3,3-hexafluoroisopropyl methacrylate/hexyl acrylate) (HFIPMA), and 2,2,3,3,4,4,4-heptafluorobutyl methacrylate (HFBMA) copolymerized with acrylic-based monomers (n-butyl, n-pentyl, and n-hexyl acrylates) to from self-healable films. Using molecular level spectroscopic (NMR, ESR, IR, Raman) and macroscopic probes (optical microscopy, tensile and dynamic mechanical measurements) supported by molecular dynamic (MD) simulations, an ultimate goal is to develop a new generation of self-healable commodity copolymers and understand molecular origins of self-healing behavior..This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.