Conductive polymers synthesized by vacuum vapour phase polymerization (VPP) were investigated and optimized by changing the oxidant solution and VPP chamber parameters for their incorporation into ‘smart window’ electrochromic devices. Additionally, the interaction of two oxidant solutions with typical electrode materials (aluminium and indium tin oxide) were examined with respect to material etching, device cosmetics and long term device degradation (over 10 000 switch cycles). Devices made with conducting polymers synthesized with the oxidant Fe(Tos)3 rather than FeCl3 produced superior device performance with respect to optical switching range (%T), switch speed and optical relaxation.

Ions are present throughout our environment-from biological systems to agriculture and beyond. Many important processes and mechanisms are driven by their presence and their relative concentration. In order to study, understand and/or control these, it is important to know what ions are present and in what concentration-highlighting the importance of ion sensing. Materials that show specific ion interaction with a commensurate change in measurable properties are the key components of ion sensing. One such type are conducting polymers. Conducting polymers are referred to as 'active' because they show observable changes in their electrical and optical (and other) properties in response to changing levels of doping with ions. For example, p-type conducting polymers such as poly(3,4ethylenedioxythiophene) and polypyrrole, can transition from semi-conducting to metallic in response to increasing levels of anions inserted into their structure. Under certain circumstances, conducting polymers also interact with cations-showing their utility in sensing. Herein, recent advances in conducting polymers will be reviewed in the context of sensing ions. The main scope of this review is to critically evaluate our current understanding of ion interactions with conducting polymers and explore how these novel materials can contribute to improving our ion-sensing capabilities.

A study using three different pairs of electrochromic polymers (ECPs) synthesized onto plaques by means of a modified vapor phase polymerization (VPP) technique is presented. Restriction of the respective polymerization times, allowed both faster and slower polymerizing monomers to be controlled, and produced blended plaques with visually diffuse interfaces. The ECPs within the blended plaques retain their individual electrochromic behavior and when encapsulated into an electrochromic device, show outstanding optical switching performance with little degradation evident over 10,000 cycles, coupled with a switching time of the order of 1 second. Blends also allow multiple diffuse color changes within an electrochromic device, due to the difference in oxidation potentials of the individual ECPs, making them candidates for adaptive camouflage use.

Conducting polymers such as poly­(3,4-ethylenedioxythiophene) (PEDOT) are widely researched for application in electronic devices. Researcher’s look to exploit the ability of these polymers to conduct electrical charge. To induce conductivity, the polymers are doped with counterions; for PEDOT, this is typically done with poly­(styrenesulfonate) or tosylate (Tos). The Tos anions inserted within the PEDOT nanostructure stabilize positive defects (holes) on the polymer’s conjugated backbone, which, in turn, facilitates electrical conduction. In this study, we use X-ray photoelectron spectroscopy to investigate the Tos doping of PEDOT within the outermost region (<15 nm) of electrochemically oxidized or reduced PEDOT:Tos nanoscale films. Computation of the predicted density of states from density functional theory studies is also conducted to aid in interpreting the ultraviolet photoelectron spectroscopy spectra. We observe that the doping of PEDOT:Tos is more complex than first thought, likely involving the nonionic triblock copolymer used during PEDOT’s oxidative polymerization. This hypothesis is corroborated by time-of-flight secondary-ion mass spectrometry measurements on the outer 2 nm of the oxidized and reduced PEDOT:Tos. The observation of complex and heightened doping near the surface opens opportunities for the deliberate surface engineering of PEDOT:Tos nanofilms in polymer electronic applications such as electrochemical transistors and electrical connections.

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