Trapping colloids near chemical stripes via critical Casimir forces

Abstract

We study theoretically and experimentally the solvent-mediated critical Casimir force acting on colloidal particles immersed in a binary liquid mixture of water and 2,6-lutidine and close to substrates which are chemically patterned with periodically alternating stripes of antagonistic adsorption preferences. These patterns are experimentally realized via microcontact printing. Upon approaching the critical demixing point of the solvent, normal and lateral critical Casimir forces generate laterally confining effective potentials for the colloids. We analyze in detail the rich behavior of the spherical colloids close to such substrates. For all patterned substrates we investigated, our measurements of these effective potentials agree with the corresponding theoretical predictions. Since both the directions and the strengths of the critical Casimir forces can be tuned by minute temperature changes, this provides a new mechanism for controlling colloids as model systems, opening encouraging perspectives for applications.

Invited contribution to Molecular Physics Special Issue on Bob Evans' 65th birthday

References in corpus (13)

• The Casimir effect: from quantum to critical fluctuations
• Universal scaling functions of critical Casimir forces obtained by Monte Carlo simulations
• Critical Casimir force in ${}^4$He films: confirmation of finite-size scaling
• Critical Casimir forces in colloidal suspensions on chemically patterned surfaces
• Monte Carlo simulation results for critical Casimir forces
• Tunability of Critical Casimir Interactions by Boundary Conditions
• Thermodynamic Casimir effect for films in the 3D Ising universality class: Symmetry breaking boundary conditions
• Critical Casimir effect for colloids close to chemically patterned substrates
• Off-critical Casimir effect in Ising Slabs with Symmetric Boundary Conditions in d=3
• Interplay of critical Casimir and dispersion forces
• Critical Casimir forces and adsorption profiles in the presence of a chemically structured substrate
• Achieving a Strongly Temperature-Dependent Casimir Effect
• Critical adsorption and critical Casimir forces for geometrically structured confinements

Cited by in corpus (12)

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• Critical Casimir Effect: Exact Results
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• Tunable critical Casimir forces counteract Casimir-Lifshitz attraction
• Three-body critical Casimir forces
• Thermodynamic Casimir Effect in Films: the Exchange Cluster Algorithm
• Critical Casimir forces in the presence of random surface fields
• Liquid bridging of cylindrical colloids in near-critical solvents
• Fluctuation-induced Interactions in Micro- and Nano-systems: Survey of Some Basic Results
• Effective interaction between a colloid and a soft interface near criticality
• The square lattice Ising model on the rectangle III: Hankel and Toeplitz determinants
• Critical Casimir forces between planar and crenellated surfaces