Mussel-Mimetic Elastomers of Varied Functionality Design for Elastomeric Composites

Abstract

Bulk viscoelasticity and tensile behavior are examined for cross-linked compounds made of mussel-mimetic elastomers of varied functionality design. During polymerization, the mussel-mimetic functionalities containing the 3,4-dihydroxyphenyl (or catechol) group can be incorporated at the molecule chain head, along the backbone, and/or at the molecule chain tail. The compounds are either unfilled or filled to the same filler volume fraction with a single filler chosen among carbon black (hydrophobic), precipitated silica (hydrophilic), and titanium oxide (hydrophilic). 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 cross-linked gum compounds. Because the mussel-mimetic functional groups exhibit obvious affinity to all 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, microscale filler dispersion is improved from the strong polymer–filler interactions.

Linear‐nonlinear dichotomy of the rheological response of particle‐filled polymers

“…This is often called filler flocculation, and this phenomenon is well documented in particle‐reinforced elastomer compounds . Known technological approaches for suppressing the filler flocculation process include introducing various silanes in silica‐filled rubber or using modified polymers which have functional groups designed for surface reaction/interaction with carbon black, silica, or other nanoparticles …”

Current Approaches to Designing Nanomaterials Inspired by Mussel Adhesive Proteins

“…Styrene-butadiene copolymer was functionalized with catechol functional groups either as a terminal group or along the polymer backbone [138,139]. When the polymer is reinforced with various types of nanoparticles (carbon black, amorphous precipitated silica, or alumina-coated titanium oxide), increased functionalization of catechol group on the polymer increased interfacial binding to the nanoparticles tested and greatly affected the bulk viscoelastic properties of the composite materials.…”

Nitro-Group Functionalization of Dopamine and its Contribution to the Viscoelastic Properties of Catechol-Containing Nanocomposite Hydrogels

“…The catechol side chain of DOPA is capable of forming strong reversible bonds with metal oxide with a measured adhesion strength averaging around 800 pN, roughly 40% that of covalent bonds . The use of network‐bound catechol (e.g., DOPA, dopamine) to increase the interfacial binding strength between polymer networks and encapsulated nanoparticles in creating nanocomposite materials (e.g., hydrogels, films, nanofibers, rubber, and tissue adhesive with drastically improved materials properties has been described. However, the effect of pH on the material properties of these nanocomposites has not yet been reported.…”