Using tapered interfaces to manipulate nanoscale morphologies in ion-doped block polymers
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Polymers/Soft Matter Research Letters
Using tapered interfaces to manipulate nanoscale morphologies in ion-doped block polymers Wei-Fan Kuan and Ellen H. Reed†, Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, Delaware 19716 Ngoc A. Nguyen, Department of Materials Science and Engineering, University of Delaware, Newark, Delaware 19716 Michael E. Mackay and Thomas H. Epps, III, Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, Delaware 19716; Department of Materials Science and Engineering, University of Delaware, Newark, Delaware 19716 Address all correspondence to Thomas H. Epps, III at [email protected] (Received 1 February 2015; accepted 14 April 2015)
Abstract We detail the influence of tapered interfaces on the nanoscale morphologies of ion-doped poly(styrene-b-oligo-oxyethylene methacrylate) block polymers (BPs). Most significantly, the location of double-gyroid network phase window was found in ion-doped normal-tapered materials, and a similar window was not detectable in the corresponding non-tapered and inverse-tapered BPs. Additionally, the effective interaction parameters, χeff, were reduced substantially in the tapered materials in comparison with their non-tapered counterparts. Overall, this work demonstrates that tapering between polymer blocks provides unique control over BP morphologies and improves the material processability (due to lower χeff ), potentially facilitating the development of future ion-conducting devices.
Solid-state polymer electrolytes have become increasingly attractive for lithium-based battery applications as they exhibit low volatility, provide sufficient mechanical strength, and increase the thermal and electrochemical stability of batteries in comparison to conventional liquid electrolytes that use flammable organic solvents.[1,2] Among the various macromolecular architectures of polymer electrolytes, block polymers (BPs) are of particular interest due to their ability to self-assemble into ordered nanostructures such as lamellae (LAM), hexagonally packed cylinders (HEX), body-centered cubic spheres (BCC), and double-gyroid (DG) networks.[3–5] A number of studies have shown that BP nanostructures, which are governed by the segregation strength (χN, χ: Flory– Huggins interaction parameter and N: degree of polymerization) and volume fraction ( f ) of the block, can form well-defined conducting pathways, which leads to enhanced ionic conductivities in comparison to corresponding random copolymers.[6,7] Of the more common BP nanostructures, the DG network phase is one of the most appealing due to its three-dimensional (3D) domain connectivity.[8] A 3D continuous morphology allows each domain to contribute directly to the modulus of the material, which leads to improvements in toughness, stress at break, and high-temperature creep resistance;[9,10] thus, a network morphology is desirable from a mechanical property perspective. Additionally, network morphologies can form
† Current address: Department of Chemical an
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