(253bm) Supramolecular Polymer Hydrogel Design through Molecular Dynamics Study of Octa-Acid Cavitand and Adamantane

Authors: 
Saltzman, A. L., Tulane University
Ashbaugh, H., Tulane University
Supramolecular polymer (SMP) hydrogels are an exciting class of smart materials, which regenerate through guest/host connections incorporated into the polymer network. [1] Such materials are biodegradable, lightweight, resilient and durable and could redefine our ability to conserve global resources. An important step to discovering a polymer hydrogel thermodynamically driven to regenerate is study of the hydrophobic effect â?? the direction of guest and host as determined by aqueous solvent â?? and its ability to direct guest/host pairings. Many classes of organic chemicals such as cyclodextrins, deep octa-acid cavitands (OA) and curcubiturils have been shown to have a strongly hydrophobic interior with a hydrophobic exterior, making them suitable for hydrophobic directed assembly with any hydrocarbon. [2],[3] Existing polymer simulations focus on adamantine as a potential guest, and our experimentation focuses on adamantine and OA derivatives.[4] Furthermore, our MD experiments between OA and adamantine have shown co-nonsolvency effects, where water and ethanol mixtures of ~2-5% have been shown to create a local binding maximum. This novel finding suggests competition between the solvent molecules for sites in the OA interior and could explain the origins of â??high energy waterâ? in which incomplete hydrogen binding networks alter the local thermodynamics of water inside the OA cavity. [5]

 




[1] Akira, H, et al. â??Macroscopic self-assembly through molecular regocnition.â? Nature Chemistry. 2011, 3(1), 34-37.

[2] Takahashi, K. â??Organic reactions mediated by cyclodextrins.â? Chem. Rev. 1998, 98, 2013â??2033

[3] Wanjari, P.P, B.C. Gibb, and H.S. Ashbaugh. â??Simulation optimization of spherical non-polar guest recognition by deep-cavity cavitands.â? The Journal of Chemical Physics, 2013, 139, 234502

[4] Wang, S., C.C. Chen, and E.E. Dormidontova. "Reversible association and network formation in 3:1 ligand-metal polymer solutions.� Soft Matter, 2008, 4. 2039-2053

[5] Biederman, F, et al. â??The Hydrophobic Effect revisited â?? studies with supramolecular complexes imply high-energy water as a non covalent driving force.â? Angew. Chem. Int. Ed. 2014. 53, 11158-11171