Browsing by Author "Kuan, Wei-Fan"
Now showing 1 - 3 of 3
Results Per Page
Sort Options
Item Controlled ionic conductivity via tapered block polymer electrolytes(Royal Society of Chemistry, 2015-01-23) Kuan, Wei-Fan; Remy, Roddel; Mackay, Michael E.; Epps, Thomas H. III; Wei-Fan Kuan, Roddel Remy, Michael E. Mackay and Thomas H. Epps, III; Kuan, Wei-Fan; Remy, Roddel; Mackay, Michael E.; Epps, Thomas H. IIIWe present the design of novel solid electrolytes using tapered block polymers (TBPs). In this work, we synthesize a series of TBPs via atom transfer radical polymerization (ATRP) consisting of rigid polystyrene and ion-conducting poly(oligo-oxyethylene methacrylate) segments and explore the role of tapered interfaces on ion transport. Previous studies on TBPs have shown that manipulating the taper composition in block polymers can reduce the unfavorable polymer–polymer interactions between blocks, enabling the design for highly-processable (lower order–disorder transition temperature) polymer electrolytes. Herein, we demonstrate that the taper profile and taper volume fraction significantly impact the glass transition temperatures (Tgs) in block polymer electrolytes, thus affecting the ionic conductivity. Additionally, we find that the normal-tapered materials with z60 vol% tapering exhibit remarkable improvements in ionic conductivity (increase z190% at 20 C and increase z90% at 80 C) in comparison to their non-tapered counterparts. Overall, our TBPs, with controllable interfacial interactions, present an exciting opportunity for the fabrication of cost-effective, highly-efficient, and stable energy storage membranes.Item Interfacial-modified block polymers for lithium battery electrolytes(University of Delaware, 2015) Kuan, Wei-FanBlock polymer (BP) electrolytes have become increasingly attractive for lithium-based battery applications due to their low volatility, sufficient mechanical strength, and thermal and electrochemical stability in comparison to conventional liquid electrolytes. However, current BP electrolytes suffer from poor conductivity near room temperatures (due to polymer crystallization) and high processing costs (due to unfavorable polymer-polymer interactions). To overcome the above limitations, this dissertation proposes a design of new BP electrolytes with a specific focus on network nanostructures using tapered block polymers (TBPs). The work presented in this dissertation examined the morphological, thermal, and electrical properties of TBPs. Incorporating a taper interface in BPs was found to reduce the unfavorable polymer-polymer interactions and stabilize additional morphologies in salt-doped BPs. Most significantly, a double gyroid network window was located in the salt-doped normal-tapered system. Additionally, the tapered interfaces demonstrated a unique handle for manipulating the glass transition temperature (Tg) of BP electrolytes through adjustments in the taper profile and taper volume fraction, thus enabling control over the ionic conductivity. Finally, a novel synthetic strategy for generating dual-tapered triblock terpolymers was presented. An alternating gyroid-forming tapered triblock terpolymer was generated, showing the ability to retain network structures in dual-tapered BP systems. Overall, the approaches presented in this dissertation provide the opportunity to design cost-effective, highly-efficient, and stable energy storage devices.Item Synthesis and characterization of bicontinuous cubic poly(3,4-ethylene dioxythiophene) gyroid (PEDOT GYR) gels(Royal Society of Chemsitry, 2015-01-12) Cho, Whirang; Wu, Jinghang; Shim, Bong Sup; Kuan, Wei-Fan; Mastroianni, Sarah E.; Young, Wen-Shiue; Kuo, Chin-Chen; Epps, Thomas H. III; Martin, David C.; Whirang Cho, Jinghang Wu, Bong Sup Shim, Wei-Fan Kuan, Sarah E. Mastroianni, Wen-Shiue Young, Chin-Chen Kuo, Thomas H. Epps, III and David C. Martin; Cho, Whirang; Wu, Jinghang; Shim, Bong Sup; Kuan, Wei-Fan; Mastroianni, Sarah E.; Young, Wen-Shiue; Kuo, Chin-Chen; Epps, Thomas H. III; Martin, David C.We describe the synthesis and characterization of bicontinuous cubic poly(3,4-ethylenedioxythiophene) (PEDOT) conducting polymer gels prepared within lyotropic cubic poly(oxyethylene)10 nonylphenol ether (NP-10) templates with Ia[3 with combining macron]d (gyroid, GYR) symmetry. The chemical polymerization of EDOT monomer in the hydrophobic channels of the NP-10 GYR phase was initiated by AgNO3, a mild oxidant that is activated when exposed to ultraviolet (UV) radiation. The morphology and physical properties of the resulting PEDOT gels were examined as a function of temperature and frequency using optical and electron microscopy, small-angle X-ray scattering (SAXS), dynamic mechanical spectroscopy, and electrochemical impedance spectroscopy (EIS). Microscopy and SAXS results showed that the PEDOT gels remained ordered and stable after the UV-initiated chemical polymerization, confirming the successful templated-synthesis of PEDOT in bicontinuous GYR nanostructures. In comparison to unpolymerized 3,4-ethylenedioxythiophene (EDOT) gel phases, the PEDOT structures had a higher storage modulus, presumably due to the formation of semi-rigid PEDOT-rich nanochannels. Additionally, the storage modulus (G′) for PEDOT gels decreased only modestly with increasing temperature, from ∼1.2 × 105 Pa (10 °C) to ∼7 × 104 Pa (40 °C), whereas G′ for the NP-10 and EDOT gels decreased dramatically, from ∼5.0 × 104 Pa (10 °C) to ∼1.5 × 102 Pa (40 °C). EIS revealed that the impedance of the PEDOT gels was smaller than the impedance of EDOT gels at both high frequencies (PEDOT ∼102 Ω and EDOT 2–3 × 104 Ω at 105 Hz) and low frequencies (PEDOT 103–105 Ω and EDOT ∼5 × 105 Ω at 10−1 Hz). These results indicated that PEDOT gels were highly ordered, mechanically stable and electrically conductive, and thus should be of interest for applications for which such properties are important, including low impedance and compliant coatings for biomedical electrodes.