Confined\nAssemblies of Colloidal Particles with Soft\nRepulsive Interactions

Abstract

We investigate the microconfinement\nof charged silica nanoparticles\ndispersed in refractive index matching monomers in poly­(dimethylsiloxane)\n(PDMS) porous membrane. Here, the silica colloidal particles interact\nwith each other and the pore wall via electrostatic double layer forces.\nDifferent from the hard sphere systems where the assembled morphologies\nare prescribed by the diameter ratio between the cylindrical confinement\nand the nanoparticles, here we observe a much richer variety of assemblies\nthat are highly sensitive to both bulk and local nanoparticle concentration\nwith fixed particle size and channel size. The experimentally observed\nassembly morphologies are consistent with theoretical predictions\nfrom the literature, based on Yukawa potential in the low packing\ndensity regime. Also, most of the configurations found in the experiment\nare well described by computer simulations using pairwise additive\nlong-range repulsive interactions, demonstrating the ability to control\nthe system to obtain a desired structure.