Single Chain Hydration and Dynamics of Mussel-Inspired Soybean-Based Adhesive

AH Mokarizadeh and N Kumar and A Joy and A Dhinojwala and M Tsige, JOM, 73, 2460-2470 (2021).

DOI: 10.1007/s11837-021-04756-1

Mussels, which are marine creatures, stick strongly to various substrates underwater using foot proteins rich in amino acids like L-3,4-dihydroxyphenylalanine (DOPA). This stimulates the synthesis of catechol-containing polymers that possess strong underwater adhesion; consequently, the mechanism is ascribed solely to catechol functionality. However, polymers' adsorption state and hence adhesion are a function of hydration and intramolecular interactions, insights into which are lacking. Here, we investigate dilute solution behavior of polyester adhesive polymers containing linoleamide group for hydrophobicity (H) and catechol group to mimic DOPA functionality (D). Higher D unit content containing polymers hydrate more through catechol hydroxyl groups and explore a wide range of conformational space. Neither ester oxygen nor nitrogen atoms in the backbone show any hydration. Interestingly, all polymers show hydrophobic collapse with extent/structure depending upon content of H unit. Hydrophobic collapse due to enthalpic interactions and chain entropy enhancement via catechol group provide insights into polymers' un-adsorbed state.

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