Tannic Acid-A Universal Immobilization and Fixation Agent for Nanocarbon Materials: A Novel Strategy for Aqueous Fabrication of Functional Nanocarbon Coating onto Silicon-Based Substances

We report a feasible and universal approach to fabricate nanocarbon material (NCM) coatings onto a wide range of silicon-based substances. Benefitting from the phenolic hydroxyl and star-shaped branched molecular structure, tannic acid (TA) could act as a functional agent for immobilization and fixation of NCMs in the aqueous phase. More specifically, steered molecular dynamics simulations verified that some unionized chains of TA could tightly attach to the NCMs surface in the neutral aqueous environment by pi-pi stacking interactions, and other free arms with ionized phenolic hydroxyl could act as surface charges of the TA/NCM coacervates, resulting in enhanced colloidal stability of this dispersion. Subsequently, these free arms could also interact with the aminated silicon-based substances, enabling TA to act as a "bridge" between the NCM and the silicon-based substances to form the nanocarbon coating. The obtained polydimethylsiloxane with TA/NCM coating represents favorable electrical and thermal conductivity along with excellent electromechanical performance under the cyclic compression-release test. This strategy is a great improvement for the fabrication of NCM layers and devices, which is not necessary to make the hydrophilic modification of NCM and beneficial to enhance the interaction between the carbon layer and substrate, avoiding the coating separation from the substances.