We studied interactions of single silica nanoparticles with homeotropic surface anchoring in a confined planar nematic liquid crystal cell. Nanoparticles form stable pairs down to a size of 35 nm with the pair binding energy proportional to the size of the particle. 22 nm particles do not form stable pairs, only metastable states were observed due to strong thermal motion and electrostatic repulsion. These nanoparticles strongly interact with the confining surfaces and the larger clusters, which prevents the formation of stable homogenous dispersions. In addition we have shown that nanoparticles are strongly attracted by topological defects induced by the microparticles. The origin of the attractive forces in nanoparticle dispersions is the minimization of free energy. These forces strongly depend on the strength and type of the liquid crystal anchoring at the surface of the nanoparticles.

我们研究了单一二氧化硅纳米粒子与垂直表面锚固在受限平面向列液晶单元中的相互作用。纳米颗粒形成稳定的分子对，分子对的结合能与颗粒的大小成正比，稳定的分子对小至35 nm。22 nm粒子未形成稳定的对，由于强烈的热运动和静电排斥，仅观察到亚稳态。这些纳米粒子与约束表面和较大的团簇强烈相互作用，从而阻止了稳定均匀分散体的形成。另外，我们已经表明，纳米粒子被微粒引起的拓扑缺陷强烈吸引。纳米粒子分散体中吸引力的来源是自由能的最小化。