Molecular Insights into the Interfacial Properties of Cellulose Surfaces with Varying Types of Ionic Liquid Epoxies

F Rahmani and MA Pasquinelli, ACS APPLIED POLYMER MATERIALS, 4, 3734-3742 (2022).

DOI: 10.1021/acsapm.2c00243

Due to the excellent physio-chemical and mechanical properties, ionic liquid epoxies (ILE) can serve as a perfect material for various technologies along with many other materials as a substrate. In this study, we employed molecular dynamics simulations to gain fundamental molecular insights about a conventional epoxy and an imidazolium-based ILE and how adhesion on crystalline cellulose surfaces is affected by cross-linking and the type of ionic liquid (IL) counter anions (e.g. OAc, Cl, and TF2N) on thermo-mechanical and moisture absorption of bulk ILE were further investigated. When comparing the ILE/cellulose systems versus bulk ILE systems, the results indicate that the presence of a cellulose surface lowers the degree of cross-linking due to the adsorption of the hardener on its surface. Overall, the ILEs/cellulose exhibit a higher interfacial bonding energy than conventional epoxy/cellulose. Improved adhesion is significant for hydrophilic ILEs, which is likely attributed to hydrogen bonds formed between the cellulose and anion molecules. This computational study provides molecular-level insights into the adsorption mechanism of ILE onto a crystalline cellulose surface, leading to the design of smart and multifunctional thermoset adhesives.

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