Photoresponsive polyelectrolyte/mesoporous silica hybrid materials with remote-controllable ionic transportation

Abstract

We present a comprehensive research on the photo-induced multi-responsibility of azobenzene(azo) diblock copolymer (BPC) grafted from the surface of mesoporous silica as a light-triggered and controllable ions transport system. The surface-initiated RAFT method was used to grow sequentially a first poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) block serving as an inner layer for the pH and thermal responsibility and a second terminal azo block functionalizing the trans-cis photoisomerization to control the closure or opening of the brushes in water. We show that the ions conductivity of hybrid system could be controlled by the second block switchable between the coil-recoil brush chain states in response to pH or temperature change or exposure to light. It was confirmed a suitable composition ratio of azo BPC brushes could significantly influence the hydrophilicity and polarity of the out layer with light, resulting the protonation or gelation of PDMAEMA block. For example, the Ru(NH3)63+ cations as probing ions was employed to prototyping the controlled permselectivity triggered by the UV light exposure. This kind of hybrid material is particularly interesting in the versatile utility for drug delivery, separating, biomimic sensor and so on.