Prof. Timothy E. Long Profile

Prof. Timothy E. Long

at Virginia Polytechnic Institute and State Univ

SPIE Involvement:

Author

Publications (5)

Proceedings Article | 4 April 2012 Paper

Study of the effects of ionic liquids on lipid bilayers

Taylor Young, Stephen Sarles, Tianyu Wu, Matthew Green, Timothy Long, Donald Leo

Proceedings Volume 8339, 833906 (2012) https://doi.org/10.1117/12.915078

KEYWORDS: Liquids, Electrodes, Interfaces, Capacitance, Ions, Sensors, Ultraviolet radiation, Water, Chemistry, Microscopes

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Proceedings Article | 29 March 2011 Paper

Multilayered polypyrrole-gold-polyvinylidene fluoride composite actuators

Colin Smith, Su Chul Yang, Timothy Long, Shashank Priya

Proceedings Volume 7976, 797625 (2011) https://doi.org/10.1117/12.880692

KEYWORDS: Actuators, Ferroelectric polymers, Polymers, Multilayers, Scanning electron microscopy, Composites, Gold, Electrodes, Video, Robotics

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Proceedings Article | 6 April 2009 Paper

Electromechanical performance and membrane stability of novel ionic polymer transducers constructed in the presence of ionic liquids

Andrew Duncan, Donald Leo, Timothy Long, Barbar Akle, Jong Park, Robert Moore

Proceedings Volume 7287, 728711 (2009) https://doi.org/10.1117/12.815874

KEYWORDS: Liquids, Polymers, Scattering, Electroactive polymers, Transducers, X-rays, Laser scattering, Glasses, Resistance, Actuators

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Ionic polymer transducers (IPT) are a class of devices that leverage electroactive polymers (EAP), specifically electrolyte-swollen ionomeric membranes, to perform energy conversions. Energy transformation from input to output is referred to as transduction and occurs between the electrical and mechanical domains. The present study expands on IPT investigations with a novel series of sulfonated polysulfones (sBPS), with specific interest in the effect of polymer topology on actuator performance. A hydrophilic ionic liquid was combined with a series of sBPS through a casting method to create hydrated membranes that contained target uptakes (f) of the diluent. The ionic liquid's hydrophilic, yet organic nature raised the issue of its degree of compatibility and miscibility with the microphase separated domains of the host ionomeric membrane. Initial studies of the ionomer - ionic liquid morphology were performed with synchrotron small angle X-ray scattering (SAXS). The effective plasticization of the membranes was identified with dynamic mechanical analysis (DMA) in terms of varied storage modulus and thermal transitions with ionic liquid uptake. Electrical impedance spectroscopy (EIS) was employed to quantify the changes in ionic conductivity for each sBPS ionomer across a range of uptake. Combined results from these techniques implied that the presence of large amounts of ionic liquid swelled the hydrophilic domains of the ionomer and greatly increased the ionic conductivity. Decreases in storage modulus and the glass transition temperature were proportional to one another but of a lesser magnitude than changes in conductivity. The present range of ionic liquid uptake for sBPS was sufficient to identify the critical uptake (f_c) for three of the four ionomers in the series. Future work to construct IPTs with these components will use the critical uptake as a minimum allowable content of ionic liquid to optimize the balance of electrical and mechanical properties for the device components.