Formation of Janus TiO2 Nanoparticles by a Pickering Emulsion Approach Applying Phosphonate Coupling Agents
Formation of Janus TiO2 Nanoparticles by a Pickering Emulsion Approach Applying Phosphonate Coupling Agents
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DOI：
10.1166/jnn.2011.4745
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发表时间：
2011-10-01
影响因子：
--
通讯作者：
Kickelbick, Guido
中科院分区：
文献类型：
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作者：
Bachinger, Angelika;Lvanovici, Sorin;Kickelbick, Guido
采用Pickering乳液法对TiO（2）纳米粒子进行了各向异性表面改性。采用溶胶-凝胶法制备了TiO（2）纳米粒子，并对其形貌和尺寸进行了控制。所得胶体进一步用作形成水包油型Pickering乳液的稳定剂。出于比较的原因，在官能化实验中还使用了市售的二氧化钛纳米颗粒（Evonik TiO（2）P25）。存在于油相中的有机磷偶联剂配位到纳米颗粒的表面。以这种方式，实现了颗粒的各向异性表面改性，这增加了Pickering乳液的稳定性。光谱研究表明，存在的有机磷偶联剂表现出共价键合到颗粒的表面。热重分析证实了较低的表面覆盖率的乳液改性的颗粒相比，那些改性的悬浮液。含甲基丙烯酸酯基团的有机磷偶联剂与有机单体（甲基丙烯酸甲酯）作为Pickering乳液的油相反应，得到杂化TiO（2）@聚合物球。所得颗粒的光谱表征表明，膦酸酯配位到TiO（2）表面，并在同一时间与MMA的油滴内的共聚。分离的最终产物的形态学研究表明，该材料是由聚合物球与稳定的TiO（2）纳米粒子在其表面上。
Anisotropic surface modification of TiO(2) nanoparticles was achieved applying a Pickering emulsion approach. TiO(2) nanoparticles were prepared by sol gel routes which allowed an excellent control over their size and morphology. The obtained colloids were further used as stabilizers in the formation of oil-in-water Pickering emulsion. For reasons of comparison, also commercially available titanium dioxide nanoparticles (Evonik AEROXIDE (R) TiO(2) P25) were used in the functionalization experiments. An organophosphorus coupling agent present in the oil phase coordinated to the surface of the anatase nanoparticles. In such a way an anisotropic surface modification of the particles was achieved which increased the stability of the Pickering emulsion. Spectroscopic studies revealed the presence of organophosphorus coupling agents which exhibited a covalent bonding to the surface of the particles. Thermogravimetric analyses confirmed a lower surface coverage of the particles modified in emulsion compared to those modified in suspension. Reactions of organophosphorus coupling agents containing an additional methacrylate group applying an organic monomer (methyl methacrylate) as the oil phase of the Pickering emulsion resulted in hybrid TiO(2)@polymer spheres. Spectroscopic characterization of the resulting particles revealed that the phosphonates were coordinated to the TiO(2) surface and at the same time copolymerized with the MMA within the oil droplet. Morphological investigations of the isolated final product showed that the material was composed of polymer spheres with the stabilizing TiO(2) nanoparticles on their surface.