【摘要】 含酸酐两亲硅烷偶联剂在颗粒表面吸附形成自组装单分子膜,可通过溶胶-凝胶法制备二氧化硅Janus纳米片.本文通过对二氧化硅Janus纳米片选择改性在一侧偶联氨基,制备了羧基/氨基复合的Janus纳米片.纳米片两侧的羧基与氨基具有不同的p H值响应性,表现出相应的荷电性质及润湿性.二者共同作用,引起纳米片特殊的分散和聚集行为.在较低或较高p H值水平,纳米片表现为Janus特性,分散良好.在中间p H值范围,纳米片两侧羧基、氨基相反电荷相互吸引导致层层组装聚集并沉淀.更多还原

【Abstract】 Janus materials have witnessed fast development due to their diversified promising performances and practical applications. Compared with their spherical counterparts, Janus nanosheets have gained more concerns for their highly anisotropic shape besides chemistry. Herein, 3.5 nm ultrathin and flexible Janus nanosheets with carboxyl group terminated onto one side are fabricated by surface sol-gel process of the self-assembled monolayer of an amphiphilic silane onto the template Ca CO3 particle firstly. Amine/acid composite Janus nanosheets are further derived from these carboxyl group terminated silica Janus nanosheets by selective conjugation with amine groups onto the other side. The amine/acid composite Janus nanosheets are dually p H responsive, and well dispersible in aqueous solution at both low and high p H levels. The nanosheets are aggregated forming multi-layered face-to-back superstructures at intermediate p H levels. This is originated by the opposite electrostatic interaction between the carboxyl and the amine groups. This approach can be extended to other silanes, and a huge family of Janus nanosheets is expected with tunable composition and performance.更多还原