Department of Chemistry, Centre for Self-Assembled Chemical Structures (CSACS) , 801 Sherbrooke Street West, Montreal, Quebec H3A 0B8, Canada.
Department of Chemical Engineering, McGill University , Montreal, Quebec H3A 0C5, Canada.
Langmuir. 2016 Aug 23;32(33):8442-50. doi: 10.1021/acs.langmuir.6b02256. Epub 2016 Aug 9.
Nanoparticle-liquid crystal (NP-LC) composites based on hydrogen bonding were explored using a model system. The ligand shells of 3 nm diameter zirconium dioxide nanoparticles (ZrO2 NPs) were varied to control their interaction with 4-n-hexylbenzoic acid (6BA). The miscibility and effect of the NPs on the nematic order as a function of particle concentration was characterized by polarized optical microscopy (POM), fluorescence microscopy and (2)H NMR spectroscopy. Nonfunctionalized ZrO2 NPs have the lowest miscibility and strongest effect on the LC matrix due to irreversible binding of 6BA to the NPs via a strong zirconium carboxylate bond. The ZrO2 NPs were functionalized with 6-phosphonohexanoic acid (6PHA) or 4-(6-phosphonohexyloxy)benzoic acid (6BPHA) which selectively bind to the ZrO2 NP surface via the phosphonic acid groups. The miscibility was increased by controlling the concentration of the pendant CO2H groups by adding hexylphosphonic acid (HPA) to act as a spacer group. Fluorescence microscopy of lanthanide doped ZrO2 NPs showed no aggregates in the nematic phase below the NP concentration where aggregates are observed in the isotropic phase. The functionalized NPs preferably concentrate into LC defects and any remaining isotropic liquid but are still present throughout the nematic liquid at a lower concentration.
基于氢键的纳米颗粒-向列相液晶（NP-LC）复合材料采用模型体系进行了研究。改变了 3nm 直径的二氧化锆纳米粒子（ZrO2 NPs）的配体壳，以控制其与 4-正己基苯甲酸（6BA）的相互作用。通过偏光显微镜（POM）、荧光显微镜和（2）H NMR 光谱研究了纳米粒子浓度对向列相有序性的混合作用。由于 6BA 通过强的锆羧酸键不可逆地结合到 NPs 上，因此未功能化的 ZrO2 NPs 具有最低的混合性和对 LC 基质的最强作用。ZrO2 NPs 通过 6-膦酸己酸（6PHA）或 4-（6-膦酸己氧基）苯甲酸（6BPHA）功能化，通过磷酸基团选择性地结合到 ZrO2 NP 表面。通过添加己基磷酸（HPA）作为间隔基团来控制侧接 CO2H 基团的浓度，从而增加了混合性。镧系掺杂 ZrO2 NPs 的荧光显微镜显示，在各向同性相中观察到聚集体的 NP 浓度以下的向列相中没有聚集体。功能化的 NPs 更倾向于浓缩到 LC 缺陷和任何剩余的各向同性液体中，但在较低浓度下仍存在于整个向列相液体中。
