Attractive interaction and bridging transition between neutral colloidal particles due to preferential adsorption in a near-critical binary mixture

Abstract

We examine the solvent-mediated interaction between two neutral colloidal particles due to preferential adsorption in a near-critical binary mixture. We take into account the renormalization effect due to the critical fluctuations using the recent local functional theory $[$J. Chem. Phys. {\bf 136}, 114704 (2012)$]$. We calculate the free energy and the force between two colloidal particles as functions of the temperature $T$, the composition far from the colloidal particles $c_{\infty }$, and the colloid separation $\ell$. The interaction is much enhanced when the component favored by the colloid surfaces is poor in the reservoir. For such off-critical compositions, we find a surface of a first-order bridging transition $\ell ={\ell }_{\mathrm{cx}}(T,c_{\infty })$ in the $T$-$c_{\infty }$-$\ell$ space in a universal, scaled form, across which a discontinuous change occurs between separated and bridged states. This surface starts from the bulk coexistence surface (CX) and ends at a bridging critical line $\ell ={\ell }_c(T)$. On approaching the critical line, the discontinuity vanishes and the derivatives of the force with respect to $T$ and $\ell$ both diverge. Furthermore, bridged states continuously change into separated states if $c_{\infty }$ (or $T$) is varied from a value on CX to value far from CX with $\ell$ kept smaller than ${\ell }_c(T)$.

15 pages, 17 figures

References in corpus (7)

• Tunability of Critical Casimir Interactions by Boundary Conditions
• Capillary bridging and long-range attractive forces in a mean-field approach
• Salt-induced changes of colloidal interactions in critical mixtures
• Interplay of critical Casimir and dispersion forces
• Off-critical Casimir effect in Ising Slabs with Symmetric Boundary Conditions in d=3
• Colloidal aggregation and critical Casimir forces
• Phase separation in a binary mixture confined between symmetric parallel plates: Capillary condensation transition near the bulk critical point

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