Mussel-Mimetic Elastomers for Nanocomposites

    Bulk viscoelasticity and tensile behavior are examined for crosslinked compounds made of mussel-mimetic elastomers of varied functionality design. The mussel-mimetic functionalities containing 3,4-dihydroxyphenyl (or catechol) group can be incorporated at initiation, along the backbone, and/or at molecule chain end. The compounds are either unfilled or filled to the same filler volume fraction with single filler chosen among hydrophobic carbon black, hydrophilic precipitated silica, and hydrophilic titanium oxide. For polymers bearing multiple mussel-mimetic functional groups, the polymer cold flow resistance becomes significantly enhanced arising from the strong intermolecular hydrogen bonding interactions. Such strong intermolecular hydrogen bonding interactions also affect the bulk viscoelasticity and tensile behavior for the crosslinked gum compounds. As the mussel-mimetic functional groups exhibit obvious affinity to all the three types of filler particles, the extent of modification to bulk viscoelasticity and reinforcement for the filled compounds is observed to vary with the distribution of such functionalities along a polymer molecule, the chemical groups immediately next to the catechol group, and the specific type of filler. As expected, micro-scale filler dispersion is improved with strong polymer-filler interactions.