Silk-Ion Jelly: a novel ion conducting polymeric material with high conductivity and excellent mechanical stability

In this work, a thin, flexible and mechanically stable polymer conducting material (Silk-Ion Jelly) was developed though application of Ion Jelly on to silk fabrics. Ion Jelly was prepared through jellification of a room temperature ionic liquid, 1-butyl-3-methyl-imidazolium dicyanamide ([bmim][dca]) using gelatin and water and applied to silk fabrics using two different processes: impregnation and in-situ. Various parameters influencing ionic conductivity such as Ion Jelly composition (ratio of [bmim][dca], water and gelatin) and incorporation as well as the type of application process were thoroughly investigated. It was observed that the Ion Jelly compositions containing lower gelatin and water ratio as well as application through in-situ process at high temperature (200ºC) led to considerable improvement in conductivity, mainly due to increased [bmim][dca] concentration, structural flexibility and reduced silk crystallinity. Silk-Ion Jelly prepared using optimized conditions showed excellent mechanical stability and possessed high room temperature conductivity (2.9x10-3 S. cm-1), similar to [bmim][dca], and therefore, this novel ion conducting material may find potential applications in electrochemical devices due to its eco-friendly preparation route using biomaterials and green solventsThis research work has been supported by Fundacao para a Ciencia e Tecnologia (FCT, Portugal) through the research grant PTDC/CTM/100244/2008

Polyelectrolyte-in-ionic-liquid electrolytes

Novel polymer electrolyte materials based on a polyelectrolyte-in-ionic-liquid principle are described. A combination of a lithium 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPSLi) and N,N&prime;-dimethylacrylamide (DMMA) are miscible with the ionic liquid, 1-ethyl-3-methylimidazolium dicyanamide (EMIDCA). EMIDCA has remarkably high conductivity (&ge;&thinsp;2&thinsp;&middot;&thinsp;10&minus;2 S&thinsp;&middot;&thinsp;cm&minus;1) at room temperature and acts as a good solvating medium for the polyelectrolyte. At compositions of AMPSLi less than or equal to 75 mol-% in the copolymer (P(AMPSLi-co-DMAA)), the polyelectrolytes in EMIDCA are homogeneous, flexible elastomeric gel materials at 10&thinsp;&minus;&thinsp;15 wt.-% of total polyelectrolyte. Conductivities higher than 8&thinsp;&middot;&thinsp;10&minus;3 S&thinsp;&middot;&thinsp;cm&minus;1 at 30&thinsp;&deg;C have been achieved. The effects of the monomer composition, polyelectrolyte concentration, temperature and lithium concentration on the ionic conductivity have been studied using thermal and conductivity analysis, and pulsed field gradient nuclear magnetic resonance techniques.<br /

The additive effect of zwitterion and nano-particles on ion dissociation in polyelectrolytes

To realise the battery potential of gel polyelectrolytes greater ion dissociation, ultimately leading to higher conductivities, must be achieved. Higher conductivities will result through increasing the ion-dissociating properties of the gel polyelectrolyte. The poor degree of ion dissociation arises as the active ion tends to remain in close proximity to the backbone charge. Nano-particle inorganic oxides, and zwitterionic compounds have been shown to act as dissociation enhancers in certain polyelectrolyte systems. In an attempt to further increase ion dissociation the addition of both TiO2 nano-particles and a zwitterionic compound based on 1-butylimidazolium-3-N-(butanesulphonate) were added to the gel polyelectrolyte system poly (Li-2-acrylamido-2-methyl-1-propane sulphonate-co-N,N&prime;-dimethylacrylamide), poly(Li-AMPS-co-DMAA) to determine if a synergistic effect occurs. Two different solvents were used to determine the breadth of applicability of the additive effect. The use of both dissociators resulted in the maximum ionic conductivity being achieved at lower nano-particle concentrations when compared to an identical system without zwitterion.<br /

In situ photopolymerization of a gel ionic liquid electrolyte in the presence of iodine and its use in dye sensitized solar cells

We report for the first time an in situ photopolymerization of model co-monomers, 2-hydroxyethyl methacrylate (HEMA) and tetra (ethylene glycol) diacrylate (TEGDA), in an IL electrolyte containing I2 for DSSCs. TiO2 nanoparticles were used as the photo-initiator and co-gelator in a charge transfer polymerization reaction. The gel-IL polymer obtained was characterized in terms of the diffusion properties of the electrolyte. Preliminary results from DSSCs assembled using the gel-IL electrolyte showed energy conversion efficiency of 3.9% at 1 sun (AM1.5) and 5.0% at 0.39 sun illumination.<br /

Solid state actuators based on polypyrrole and polymer-in-ionic liquid electrolytes

Novel polymer-in-ionic liquid electrolytes (PILEs) have been developed for solid state electrochemical actuators based on polypyrrole. The active polymer electrodes are readily oxidized/reduced without degradation in the PILE. It was found that the actuator cycle life is significantly enhanced in the PILE as is the &lsquo;shelf life&rsquo; of the device.<br /