This project was performed in collaboration with Prof. Y-N Young (NJIT) and H.A. Stone (Princeton U.) and has aimed to developing theoretical and computational modeling approaches that incorporate nanoscale and molecular-level interactions to predict more accurately the behavior of lipid bilayer membranes (LBMs) near a solid substrate or micro/nanoparticle immersed in liquid media. In particular, computational work using molecular dynamics simulations focused on the effect of solvation (or hydration) layers that form at liquid-solid interfaces and give rise to so-called solvation (or hydration) forces not considered in the conventional approaches for modeling the dynamics of lipid bilayers near interfaces.  An important finding of the theoretical and computational work led by the PI’s group has been that the surface energy commonly employed in models to characterize the adhesion, curvature, and rupture of a LBM cannot be readily considered as a material property of the system. Results from this project document and rationalize the need to consider the surface energy, commonly related to the Young contact angle and work of adhesion, as a configuration- dependent parameter when the separation between the interfaces approaching contact (or in liquid-mediated contact) is below 10 to 15 molecular solvent diameters.

This project supported the professional development and graduation of 2 PhD students from underrepresented groups in STEM by providing training and mentoring on the application of computational tools for scientific computing and data mining. In particular, the PhD students involved in this project learned to employ large-scale molecular dynamics simulations using both fully atomistic and coarse-grained approaches, and machine learning methods for determining regime maps and phase diagrams from the results of such simulations. One of the PhD students in this project received supplemental support for his participation in the AGEP program with professional development and mentorship activities developed within the PI’ host institution.  A third PhD student was additionally supported to complete a summer internship at Brookhaven National Laboratory, for which computational methods were applied to predict microphase separation in thin films of block copolymers onto well wetted substrates.

The outcomes of this project included collaborations with researchers at ESPCI (France), Utrecht University (Netherlands), Rutgers U. and Johns Hopkins U. that resulted in the publication of 2 articles in Physical Review Letters that study the interaction of micro/nanoparticles at water-water interfaces [Image 1] and solid-liquid interfaces [Image 2] where the nanoscale structure of the interface produces unexpected effects. The PI also produced a theoretical model published in JCP Communications [Image 3] for predicting the effective diffusivity in the presence of multiple energy barriers over nanoscale spatial lengths, such as those induced by nanoscale interfacial features and/or the solvation (or hydration) forces of interest in this project.  An additional publication in Soft Matter [Image 4] in collaboration with Y-N Young and H.A. Stone reported the effect of hydration forces on the surface energy and Young contact angle and proposed an analytical model to include these nanoscale effects on conventional continuum descriptions for predicting capillary adhesion.

The methods and tools developed in this project are being currently employed by the PI and collaborators in this project to further understand adhesion problems that involve soft material interfaces and to develop technical applications that include food stabilizers, self-assembly of nanomaterials, and energy storage devices.

Last Modified: 03/06/2023
Modified by: Carlos E Colosqui