SPP 2171 Spring Conference: Dynamic Wetting of Flexible, Adaptive, and Switchable Substrates

Conducting polymers (CPs) are used in a wide range of electrochemical devices, such as organic field effect transistors, batteries, actuators, and chemical-biological sensors. Compared to other conducting materials, CPs offer advantages such as lightweight, low cost, non-toxicity, flexibility, ease of processing, low-voltage operation (around 1 volt), and low power consumption. Poly(3-hexylthiophene) [1] is the most studied material in our group due to its high conductivity and electrochromic properties, which are controlled by its doping state. [2] In this context, electrochemical doping is explored as a versatile tool to change chemical and physical properties of P3HT, with a particular focus on wettability.
We observe significant wettability changes of spin-coated P3HT films which are doped by an ex-situ electrochemical doping strategy. The sessile drop technique is applied under controlled relative humidity (r. h.) condition, and yields water contact angle between 67° to 112°. Further investigations involve dynamic wettability measurements to determine hysteresis effect. Direct correlations with in-situ spectroelectrochemistry, solid state conductivity and absorption measurements allow us to quantify the degree of doping. The role of electrochemical doping on morphological changes gives further insights into ionic mixed conducting polymer films as flexible, adaptive substrates for wetting applications.