@article{an_addington_long_rotnicki_sliwinska-bartkowiak_thommes_gubbins_2023, title={The Nanoscale Wetting Parameter and Its Role in Interfacial Phenomena: Phase Transitions in Nanopores}, volume={39}, ISSN={["1520-5827"]}, DOI={10.1021/acs.langmuir.3c01925}, abstractNote={Through analysis of the statistical mechanical equations for a thin adsorbed film (gas, liquid, or solid) on a solid substrate or confined within a pore, it is possible to express the equilibrium thermodynamic properties of the film as a function of just two dimensionless parameters: a nanoscale wetting parameter, αw, and pore width, H*. The wetting parameter, αw, is defined in terms of molecular parameters for the adsorbed film and substrate and so is applicable at the nanoscale and for films of any phase. The main assumptions in the treatment are that (a) the substrate structure is not significantly affected by the adsorbed layer and (b) the diameter of the adsorbate molecules is not very small compared to the spacing of atoms in the solid substrate. We show that different surface geometries of the substrate (e.g., slit, cylindrical, and spherical pores) and various models of wall heterogeneity can be accounted for through a well-defined correction to the wetting parameter; no new dimensionless variables are introduced. Experimental measurements are reported for contact angles for various liquids on several planar substrates and are shown to be closely correlated with the nanoscale wetting parameter. We apply this approach to phase separation in nanopores of various geometries. Molecular simulation results for the phase diagram in confinement, obtained by the flat histogram Monte Carlo method, are reported and are shown to be closely similar to experimental results for capillary condensation, melting, and the triple point. The value of the wetting parameter, αw, is shown to determine the qualitative behavior (e.g., increase vs decrease in the melting temperature, capillary condensation vs evaporation), whereas the pore width determines the magnitude of the confinement effect. The triple point temperature and pressure for the confined phase are always lower than those for the bulk phase for all cases studied.}, number={51}, journal={LANGMUIR}, author={An, Rong and Addington, Cody K. and Long, Yun and Rotnicki, Konrad and Sliwinska-Bartkowiak, Malgorzata and Thommes, Matthias and Gubbins, Keith E.}, year={2023}, month={Dec}, pages={18730–18745} }
 @article{an_huang_mineart_dong_spontak_gubbins_2017, title={Adhesion and friction in polymer films on solid substrates: conformal sites analysis and corresponding surface measurements}, volume={13}, ISSN={1744-683X 1744-6848}, url={http://dx.doi.org/10.1039/C7SM00261K}, DOI={10.1039/c7sm00261k}, abstractNote={In this work, we present a statistical mechanical analysis to elucidate the molecular-level factors responsible for the static and dynamic properties of polymer films. This analysis, which we term conformal sites theory, establishes that three dimensionless parameters play important roles in determining differences from bulk behavior for thin polymer films near to surfaces: a microscopic wetting parameter, αwx, defined as the ratio of polymer-substrate interaction to polymer-polymer interaction; a dimensionless film thickness, H*; and dimensionless temperature, T*. The parameter αwx introduced here provides a more fundamental measure of wetting than previous metrics, since it is defined in terms of intermolecular forces and the atomic structure of the substrate, and so is valid at the nanoscale for gas, liquid or solid films. To test this theoretical analysis, we also report atomic force microscopy measurements of the friction coefficient (μ), adhesion force (FA) and glass transition temperature (Tg) for thin films of two polymers, poly(methyl methacrylate) (PMMA) and polystyrene (PS), on two planar substrates, graphite and silica. Both the friction coefficient and the glass transition temperature are found to increase as the film thickness decreases, and this increase is more pronounced for the graphite than for the silica surface. The adhesion force is also greater for the graphite surface. The larger effects encountered for the graphite surface are attributed to the fact that the microscopic wetting parameter, αwx, is larger for graphite than for silica, indicating stronger attraction of polymer chains to the graphite surface.}, number={19}, journal={Soft Matter}, publisher={Royal Society of Chemistry (RSC)}, author={An, Rong and Huang, Liangliang and Mineart, Kenneth P. and Dong, Yihui and Spontak, Richard J. and Gubbins, Keith E.}, year={2017}, pages={3492–3505} }
 @article{zhuang_zhang_he_an_li_ying_wu_chen_zhou_lu_2017, title={Facile synthesis of amino-functionalized mesoporous TiO2 microparticles for adenosine deaminase immobilization}, volume={239}, journal={Microporous and Mesoporous Materials}, author={Zhuang, W. and Zhang, Y. H. and He, L. J. and An, R. and Li, B. B. and Ying, H. J. and Wu, J. L. and Chen, Y. and Zhou, J. W. and Lu, X. H.}, year={2017}, pages={158–166} }
 @article{zhuang_zhang_zhu_an_li_mu_ying_wu_zhou_chen_et al._2016, title={Influences of geometrical topography and surface chemistry on the stable immobilization of adenosine deaminase on mesoporous TiO2}, volume={139}, journal={Chemical Engineering Science}, author={Zhuang, W. and Zhang, Y. H. and Zhu, J. H. and An, R. and Li, B. B. and Mu, L. W. and Ying, H. J. and Wu, J. L. and Zhou, J. W. and Chen, Y. and et al.}, year={2016}, pages={142–151} }
 @article{an_huang_long_kalanyan_lu_gubbins_2016, title={Liquid–Solid Nanofriction and Interfacial Wetting}, volume={32}, ISSN={0743-7463 1520-5827}, url={http://dx.doi.org/10.1021/acs.langmuir.5b04115}, DOI={10.1021/acs.langmuir.5b04115}, abstractNote={Using atomic force microscopy, the nanofriction coefficient was measured systematically for a series of liquids on planar graphite, silica and mica surfaces. This allows us to explore the quantitative interplay between nanofriction at liquid-solid interfaces and interfacial wetting. A corresponding states theory analysis shows that the nanofriction coefficient, μ = dF(F)/dF(N), where FF is the friction force and FN is the normal force, is a function of three dimensionless parameters that reflect the intermolecular forces involved and the structure of the solid substrate. Of these, we show that one parameter in particular, β = ρ(s)Δ(s)σ(ls)(2), where ρ(s) is the atomic density of the solid, Δ(s) is the spacing between layers of solid atoms, and σ(ls) is the molecular diameter that characterizes the liquid-substrate interaction, is very important in determining the friction coefficient. This parameter β, which we term the structure adhesion parameter, provides a measure of the intermolecular interaction between a liquid molecule and the substrate and also of the surface area of contact of the liquid molecule with the substrate. We find a linear dependence of μ on the structure adhesion parameter for the systems studied. We also find that increasing β leads to an increase in the vertical adhesion forces FA (the attractive force exerted by the solid surface on the liquid film). Our quantitative relationship between the nanofriction coefficient and the key parameter β which governs the vertical adhesive strength, opens up an opportunity for describing liquid flows on solid surfaces at the molecular level, with implications for the development of membrane and nanofluidic devices.}, number={3}, journal={Langmuir}, publisher={American Chemical Society (ACS)}, author={An, Rong and Huang, Liangliang and Long, Yun and Kalanyan, Berc and Lu, Xiaohua and Gubbins, Keith E}, year={2016}, month={Jan}, pages={743–750} }
 @article{zhuang_li_zhu_an_lu_lu_wu_ying_2015, title={Facile synthesis of mesoporous MoS2-TiO2 nanofibers for ultrastable lithium ion battery anodes}, volume={2}, number={3}, journal={Chemelectrochem}, author={Zhuang, W. and Li, L. C. and Zhu, J. H. and An, R. and Lu, L. H. and Lu, X. H. and Wu, X. B. and Ying, H. J.}, year={2015}, pages={374–381} }
 @article{zhuang_he_zhu_an_wu_mu_lu_lu_liu_ying_2015, title={TiO2 nanofibers heterogeneously wrapped with reduced graphene oxide as efficient Pt electrocatalyst supports for methanol oxidation}, volume={40}, number={9}, journal={International Journal of Hydrogen Energy}, author={Zhuang, W. and He, L. J. and Zhu, J. H. and An, R. and Wu, X. B. and Mu, L. W. and Lu, X. H. and Lu, L. H. and Liu, X. J. and Ying, H. J.}, year={2015}, pages={3679–3688} }