Nanocomposite hydrogels rely on weak physical bonds (e.g., hydrogen bonding, ionic interactions, etc.) between the polymer network and encapsulated nanoparticles to achieve elevated materials properties and recovery after repeated deformation. Here, derivatives of an adhesive amino acid, DOPA, found in mussel adhesive proteins (e.g., dopamine and nitrodopamine) were incorporated into PEG-based nanocomposite hydrogels to enhance the interfacial binding between PEG and nano-silicate, Laponite. Nitrodopamine-modified PEG (PEG-ND) cured instantly as compared to a cure time of 1 minute for dopamine-modified PEG (PEG-D). Nitrodopamine contains an electron-withdrawing group (e.g., -NO2), which lowers its pKa for faster oxidative crosslinking. From oscillatory rheometry, values for G' and G� for PEG-ND were an order of magnitude higher than those of PEG-D. Nitro-functionalization likely increased the affinity of nitrodopamine to inorganic surfaces, resulting in enhanced viscous dissipation properties. The combination of elevated elastic and viscous properties make these nanocomposites well suited for repeated load bearing. 

Effect of nitro-functionalization on the curing rate and viscoelasticity of biomimetic nanocomposite hydrogel

246th National Meeting (2013)

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