Light-triggered pH/thermal multisensitive polyelectrolyte/ITO glass hybrid electrode

Abstract

Surfaces with stimuli-responsive properties have shown prominent applications in bioengineering, controlled drug release and biosensors in recent years. In this work, we report a surface-initiated reversible addition–fragmentation chain transfer polymerization method to graft azobenzene-containing diblock copolymer (azo-BCP) brushes onto an Indium Tin Oxide (ITO) glass surface. In this method, a sequential azo block serves as the outer layer that controls the closure or opening of the brushes, and the second block (PDMAEMA) acts as the inner layer that switches between swollen and collapsed chain states in response to different pH values and temperatures. Upon exposure to UV light, the ITO surface became more hydrophilic (>10° change of contact angles), and its friction coefficient (0.5–0.9) increased; this suggests a loose aggregation of the azo block. Additionally, the ion conductivity of the ITO surface can be influenced by the aggregation state of the azo-BCP brushes, thus leading to the transportation of light-triggered ions under various pH values and temperatures. This work provides a deep understanding of the surface properties of a sensitive hybrid material upon various stimuli for electrode purpose, thereby paving the way for the development of bioengineering and environmental sensory applications.