Amine/acid composite Janus nanosheets

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 CaCO3 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 pH responsive, and well dispersible in aqueous solution at both low and high pH levels. The nanosheets are aggregated forming multi-layered face-to-back superstructures at intermediate pH 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.

Ultrathin 2D Zirconium Metal–Organic Framework Nanosheets: Preparation and Application in Photocatalysis

“…High-aspect-ratio 2D materials with extended lateral dimensions and atomic or molecular thickness often exhibit unique physical and chemical properties radically different from those of their bulk counterparts. [1][2][3][4] As a result, 2D nanostructures are highly interesting components for functional materials in the applications of separation, optoelectronics, catalysis, and so on. [5][6][7][8][9][10] Recently, 2D metal-organic framework (MOF) nanosheets have emerged as a new member of the 2D family and drawn tremendous attention.…”

Janus Colloids toward Interfacial Engineering

“…Dispersion and aggregation transformation of the Janus nanosheet is controlled by pH. 55 Similarly, a responsive polymeric Janus nanosheet can be fabricated by cross-linking a self-assembled monolayer of reactive copolymers at an emulsion interface. 56 After the preferential growth of paramagnetic Fe 3 O 4 NPs within the cross-linked poly(carboxylic acid) side, a dual pH and magnetic responsive Janus composite nanosheet is derived.…”

Design, Synthesis, and Application of Anisotropic Janus Particles

“…The as-prepared Janus sheets are flexible due to their very thin thickness, which makes it feasible to wrap objects just with a single Janus sheet. If different silanes are chosen to selectively modify the exterior surface, the family of Janus sheets will be extended, for example, to producing amine/acid Janus sheets [45]. Also, we use reactive polymer surfactant instead of silane to self-assemble and cross-link at the oil/water interface, thus fabricating polymeric Janus sheets with pH-or magnetic-responsive character [46].…”