Search

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(3,4-ethylenedioxythiophene) 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.

The ability to sense and monitor aspects of a process or environment is becoming of utmost importance as digital technology integrates into our daily lives. This is true for agriculture where knowledge of real time levels of fertiliser in soil is empowering farmers. Such sensing and monitoring requires understanding of the structure-property-performance relationships of specific materials. In this study this relationship for the conducting polymer poly(3,4-ethylenedioxythiophene), PEDOT, and its passive doping with nitrate (NO3) is explored. The highly ordered structure of vapour deposited PEDOT doped with tosylate (Tos) is commensurate with high doping levels. In turn this correlates with the nitrate doping level in PEDOT-Tos/NO3 being sensitive to NO3 concentration in the surrounding solution. Such an understanding has impact for potentially designing other conducting polymers for ion sensing applications. Refereed/Peer-reviewed

Metallic thin films have been evaluated as adhesive layers for first surface mirrors. Thin films (0.5-4nm thick) of Cr, Cu, Ge, Sn, and Ni, capped with an over layer of 100nm of Ag have been deposited by means of ion assisted electron beam evaporation onto glass substrates. The specular reflectance, conductivity, morphology, adhesion, and abrasion resistance of the mirrors have been assessed and compared. This work demonstrates the superior Ni and Ge adhesion and abrasion resistance to Ag thin films, while Cr and again Ni are the best candidates in terms of reflectance enhancement. In particular, 4nm of Ni increases the Ag reflectance from 95.7% to 96.7%, exhibits the strongest adhesion as determined by the cross hatch tape test and the lowest loss of material after the different abrasion tests is just 50% in comparison to 100% for Ag-coated glass substrates. Refereed/Peer-reviewed

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. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42158.

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 Refereed/Peer-reviewed