pi-Conjugated polymers that are electrochemically cycled in ionic liquids have enhanced lifetimes without failure (up to 1 million cycles) and fast cycle switching speeds (100 ms). We report results for electrochemical mechanical actuators, electrochromic windows, and numeric displays made from three types of pi-conjugated polymers: polyaniline, polypyrrole, and polythiophene. Experiments were performed under ambient conditions, yet the polymers showed negligible loss in electroactivity. These performance advantages were obtained by using environmentally stable, room-temperature ionic liquids composed of 1-butyl-3-methyl imidazolium cations together with anions such as tetrafluoroborate or hexafluorophosphate.

Human embryonic stem cells (hESCs) have two properties of interest for the development of cell therapies: self-renewal and the potential to differentiate into all major lineages of somatic cells in the human body. Widespread clinical application of hESC-derived cells will require culture methods that are low-cost, robust, scalable and use chemically defined raw materials. Here we describe synthetic peptide-acrylate surfaces (PAS) that support self-renewal of hESCs in chemically defined, xeno-free medium. H1 and H7 hESCs were successfully maintained on PAS for over ten passages. Cell morphology and phenotypic marker expression were similar for cells cultured on PAS or Matrigel. Cells on PAS retained normal karyotype and pluripotency and were able to differentiate to functional cardiomyocytes on PAS. Finally, PAS were scaled up to large culture-vessel formats. Synthetic, xeno-free, scalable surfaces that support the self-renewal and differentiation of hESCs will be useful for both research purposes and development of cell therapies.

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Electrolytes play an important role in determining the performance of conducting polymer electrochromic devices. Good electrolytes should have high conductivity, large electrochemical windows, excellent thermal and chemical stability, and negligible evaporation. Room-temperature ionic liquids are ideal electrolytes to satisfy these requirements. In the present work, we explored the applications of ionic liquids as electrolytes in electrochemical synthesis of conducting polymers, in electrochemical and electrochromic characterization of both electrochemically and chemically synthesized conducting polymers and in fabrication of conducting polymer electrochromic devices. In ionic liquids, highly stable electroactivity has been obtained for polyaniline in a wide potential range covering its entire redox process of leucoemeraldine ↔ emeraldine ↔ pernigraniline for Ͼ1,000,000 cycles. During the fabrication of electrochromic devices, electrochemically synthesized polymers were employed for displays, while chemically synthesized polymers ͑via spin-coating͒ were preferable for large-area electrochromic windows. We have successfully fabricated the prototypes of alphanumeric displays and large-area (5 ϫ 5 cm) electrochromic windows. High device performance of low operation voltages ͑Ͻ1.5 V͒, high coloration contrast ͑Ͼ50%͒, fast coloration speed ͑Ͻ100 ms͒, and high coulombic efficiency ͑Ͼ98%͒ has been realized.

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