The Sukhishvili Group aims to understand and develop new types of assembled polymer materials with programmed responses to environmental stimuli, such as pH, temperature, light, or the presence of oxygen or bacteria. We also aim to understand the role of dynamic bonds in polymers, such as hydrogen bonds, boronate ester, or dynamic covalent Diels-Alder (DA) furan-maleimide bonds, on the material’s thermomechanical properties, and correlate the molecular parameters of the polymer networks (such type of bonds, extent of bond dissociation, polymer chain flexibility) with the materials’ macroscopic properties. These novel materials are designed for controlled drug delivery; latent heat storage; and protection of materials against corrosion; as well as for applications that involve materials shape morphing. Research spans the fields of polymer chemistry, physics, and materials science, and involves synthesis of polymers, their rational assembly, studies of kinetics and thermodynamics of assembled structures, and exploration of response properties of these materials. Examples of current work include:
- Dynamic polymer networks for soft robotics and thermal energy storage
- Polymer salogels for thermal energy storage
- Polyelectrolyte multilayers with controlled compliance and degradation
Dynamic polymer networks for soft robotics
Covalent Adaptive Networks (CANs) as versatile re-shapable, re-processable materials
Covalent Adaptive Networks (CANs) are polymer networks formed via dynamic covalent bonds rather than permanent ones. These materials combine the mechanical properties of traditional elastomers and thermosets–whether soft and stretchable or rigid and load-bearing–with the ability of the dynamic bonds to undergo on-demand bond reshuffling for material shape morphing and re-processing.
Solvent-free DA polymer (DAP) networks demonstrate this unique adaptability by reconfiguring their permanent shapes through the mechanism of network plasticity. Stereochemistry of DA junctions (i.e. endo-to-exo isomers) and crosslinking density play central roles in bond reshuffling rates and network reconfigurability.
Moon, Sang, Rajagopalan, Gardea, Sukhishvili, Small 2024, 21, 2407858.
Polymer salogels for thermal energy storage
Dynamic polymer networks also have applications in thermal energy storage devices by providing reversible shape stabilization of inorganic salt hydrate (ISH) phase change materials (PCMs). ISHs are unique compared to conventional polar polymer solvents such as water and aqueous salt solutions due to the high salt concentration (6-18 M) which results in unique polymer solubility and gelation behavior of neutral polar polymers such as polyvinyl alcohol (PVA). The use of polymer networks in this application is dictated by the low viscosity of molten ISHs that leads to leakage in thermal management applications. The ideal scenario for shape stabilization of ISHs is robust polymer gelation within the working temperature range of PCMs, combined with a controlled gel-to-sol transition at higher temperatures to enable the removal of the PCM from a thermal exchange module. Our group has developed several types of thermo-reversible polymer gels in salt hydrate PCMs, termed “salogels” which can mechanically stabilize ISHs with wide-ranging melting temperatures.
Rajagopalan, Zhu, Sukhishvili, J. Mater. Chem. A, 2022, 10, 21622-21632
Polyelectrolyte multilayers with controlled compliance and degradation