Assembly and Disassembly of Polymer Hybrids Using Green Solvents

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This Discovery program will explore a new methodology using green solvents to enable the assembly and dissssembly of ordered polymer nanostructures. Currently, multistep complex chemistries are required to form nanoparticles (NPs) or carbon fibers, stabilize them, then attach them to polymers or surfaces to form 3D ordered structures. Less than 9% of polymers are currently recycled in North America, with retractable plastics containing carbon or nanoparticles even less likely to be re-utilized. The processes used for making and disposing of polymers often use organic solvents which are considered volatile organic compounds (VOCs), which are becoming increasingly regulated for industrial use. These VOC solvents also provide no functionality for the self-assembly process, while end of lifetime is not considered. A new paradigm is required to make these assemblies that can be disassembled back into the NPs and polymer chains readily upon demand, that can be easily adopted for polymer recycling. Our focus for this program is to develop a new coherent approach utilizing solvent engineering that can be adopted to commodity polymer systems including the major groups of chain-growth, step-growth and epoxy polymer systems. We will harness advances in polymer and nano chemistry methods in which the polymer and nanoparticles can both be assembled and then dissembled at the end of the products useful lifetime. Advances in polymer (RAFT and catalytic) and nano (metal oxides, quantum dots), carbonaceous materials (graphene, carbon fibers, biochar) will be attached to one another using reversible linkages via catechol and reticular methods. As the bonding between the NPs and polymers needs to be rather strong (compared to H-bonding for example in supramolecular chemistry), the solvent functionality will be examined to facilitate the equilibria process and thermodynamic conditions for reversibility. Decoordination on demand is our goal. Green biobased solvents (lactates, carbonates) with supercritical fluids or ionic liquids will be examined that can control the polymer/NP reversibility, depending on solute size/shape and the solvent structure, pressure and temperature. Students will be trained in polymer and nano synthesis using our state of the art high pressure equipment and in molecular modeling (DFT and Gromacs) on what type of solvent system is best, and how biphasic systems can be used. Both the kinetics of assembly and disassembly will be experimentally measured  using insitu FTIR, Raman and NMR with the reaction steps modelled. Polymer and NP solubilities will be examined in sc-CO2 with biosolvents or biosolvent/SCF biphasic systems.  Kinetic modelling, dissolution kinetics and solubility modelling will be compared to experimental data for process engineering. This research program will provide both new HQP and new data to facilitate wide industrial adoption to help Canada compete in advanced manufacturing while helping to lead the circular economy.