Strong, rebondable, dynamic cross-linked cellulose nanocrystal polymer nanocomposite adhesives

A dynamic cross-linked polymer nanocomposite adhesive has been developed by the oxidation of a thiol functionalized semi-crystalline and/or amorphous oligomer and thiol functionalized Cellulose Nanocrystals (CNCs) to form a polydisulfide network. The resulting solid material has a melting point transition at ca. 75° C. which corresponds to the melting of the semi-crystalline and/or amorphous phase of the nanocomposite adhesive. At higher temperatures (ca. 150° C.), results in the dynamic behavior of the disulfide bond being induced, where the bonds break and reform. Two levels of adhesion are obtained, in some embodiment by (1) heating the adhesive material to 80° C. (melting the semi-crystalline and/or amorphous phase) resulting in a lower modulus/viscosity of the adhesive, thus allowing better surface wetting on a substrate and (2) heating the adhesive material to 150° C. (inducing dynamic behavior of disulfide bonds), further lowers the modulus/viscosity of the adhesive ensuring a much better surface wetting and stronger adhesive bond. The polymer adhesive has been demonstrated to bind to, relatively high surface energy substrates including metal and hydrophilic glass, and to low surface energy substrates such as hydrophobic glass.