Stimuli-responsive layer-by-layer nanocomposites

Abstract

The fast-growing area of materials prepared with the layer-by-layer (LbL) technique has become firmly established over the last three decades. Responsive LbL assemblies present one attractive type of LbL materials, useful in sensing, controlled delivery and actuation. However, stimuli-responsive LbL films made exclusively from polymers or organic molecules are somewhat restricted in the types of responses that can be applied to a material, and often suffer from poor mechanical strength and limited durability. Assembly of inorganic nanoparticles (INPs), including spherical nanoparticles, nanorods, nanotubes, and nanosheets, among others, within multilayer films brings additional benefits by not only improving mechanical, electronic, magnetic and optical properties of these materials, but also endowing them with the capability to transform external signals and transfer them to other film components. Combining INPs with temperature-, pH-, or light-responsive polymers within LbL films yields novel materials with unique characteristics and properties easily controllable by external stimuli. In this paper, we discuss strategies for designing various types of INP–organic LbL assemblies, the nature of their stimuli response and potential applications.