Molecular Dynamics Study on the Thermal Aspects of the Effect of Water Molecules at the Adhesive Interface on an Adhesive Structure

Abstract

The presence of adsorbed water on hydrophilic solid surfaces should be taken into account, especially in humid environments. It significantly reduces the adhesive strength between the epoxy resin and the adherend surface. Here, the adhesion structure of interfacial water sandwiched between bisphenol A epoxy resin and a hydroxylated silica (001) surface is investigated with microsecond molecular dynamics simulations. Specifically, interfacial water layers with initial thicknesses of 7.5, 10, and 20 Å are modeled. The density curves of water and the diglycidyl ether of bisphenol A show that at room temperature, the surface of the silica with hydroxyl groups is completely covered with a thick layer of water. For water layers thinner than 10 Å, the density of epoxy resin on the silica surface increases when the system is heated and does not return to the original density when the system is cooled. Furthermore, calculation of the interaction energy revealed that the exclusion of water from the hydroxylated surface by epoxy resin during heating can contribute to the increase in the adhesive interaction between the epoxy resin and the silica surface with hydroxyl groups.Article pubs.acs.org/Langmuir

Peel Adhesion Strength between Epoxy Resin and Hydrated Silica Surfaces: A Density Functional Theory Study

“…A recent molecular dynamics study has reported that most interfacial water molecules are pushed out by the epoxy resins. 37 It is thus possible that a small number of water molecules at the interface might affect the adhesive strength. Investigation of this effect is the next task.…”

“…These models correspond to a situation where the surface is pretreated at high temperatures. A recent molecular dynamics study has reported that most interfacial water molecules are pushed out by the epoxy resins . It is thus possible that a small number of water molecules at the interface might affect the adhesive strength.…”

Neutron Reflectivity Study on the Suppression of Interfacial Water Accumulation between a Polypropylene Thin Film and Si Substrate Using a Silane-Coupling Agent

“…This may be due to the change in the affinity of the water molecules for the interface with increasing temperature. Yoshizawa et al investigated the temperature dependence of the water-layer thickness between the surface of an epoxy resin and silica using MD simulations . As a result, the water-layer thickness tended to decrease at high temperatures owing to the change in the interfacial structure of water molecules in accordance with humidity.…”

“…Yoshizawa et al investigated the temperature dependence of the water-layer thickness between the surface of an epoxy resin and silica using MD simulations. 50 As a result, the water-layer thickness tended to decrease at high temperatures owing to the change in the interfacial structure of water molecules in accordance with humidity. The driving forces of water accumulation at the interface are considered to be electrostatic and dispersion forces working within a relatively short distance of the hydroxylated metal-oxide surface, as described in our previous publication 29 and many other studies.…”

Directly Using Paraffin as the Toughening Agent of Epoxy Composites: An Experimental and Molecular Dynamics Simulation Study

“…have been proposed, the fractured surfaces studied by SEM can provide only an indirect way to correlate the microstructure and mechanical properties, 11 overlooking some key pieces of information especially like those associated with the microscopic structure of the epoxy cross-linking network. Fortunately, atomistic molecular dynamics (MD) simulation, which can provide insightful information on the atomic scale that it is hard for experimental methods to provide, has played an important role in predicting the T g , 12 modulus, 13 volume shrinkage, 14 density, 15 frictional sliding resistance, 16 and water absorption 17,18 of the polymer composites. However, most of the MD simulation research is focused on the simplest epoxy cross-linking network (containing only epoxy resin and curing agent) or the interfacial characteristics between epoxy resin and other components such as carbon fiber, 19 graphene, 20 CNTs, 21 silica, 22 etc.…”