The ionic conductivity and glass transition temperatures of nanostructured block copolymer electrolytes composed of polystyrene-b-poly(ethylene oxide) (SEO) doped with lithium bis(trifluoromethanesulfone)imide (LiTFSI) were studied in the small molecular weight limit (between 2.7 and 13.7 kg mol–1). In this range, the annealed conductivity exhibits a nonmonotonic dependence on molecular weight, decreasing with increasing molecular weight in the small molecular weight limit before increasing when molecular weight exceeds about 10 kg mol–1. We show that annealed electrolyte conductivity is affected by two competing factors: the glass transition temperature of the insulating polystyrene (PS) block and the width of the conducting poly(ethylene oxide) (PEO) channel. In the low molecular weight limit, all ions are in contact with both PS and PEO segments. The intermixing between PS and PEO segments is restricted to an interfacial zone of width, λ. Our experiments suggest that λ is about 5 nm. The fraction of ions affected by the interfacial zone decreases as the conducting channel width increases. We also study the effect of thermal history on the conductivity of the block copolymer electrolytes. Our data suggest that long-range order impedes ion transport.

A polyHIPE is a highly porous polymer synthesized from monomers within the external phase of a high internal phase emulsion (HIPE). The large amount of difficult to remove surfactant needed for HIPE stabilization can affect the properties of the resulting polymer. A Pickering emulsion is a surfactant‐free emulsion stabilized by solid particles that preferentially migrate to the interface. In this article, the synthesis of crosslinked polyacrylate polyHIPEs based on Pickering HIPEs stabilized using silane‐modified silica nanoparticles is described and the effects of the synthesis parameters on the porous structure are discussed. The silane chemistry, silane content, and nanoparticle content had significant effects on the size of the polyhedral, relatively closed‐cell polyHIPE voids that resulted from aqueous‐phase initiation. Increasing the mixing intensity reduced the wall thickness and produced a more open‐cell structure. The locus of initiation had a significant effect on polyHIPE morphology. Organic‐phase initiation yielded larger, more spherical voids from the more extensive coalescence before the structure could be “locked‐in” at the gel point. Most significantly, the nanoparticles were located within the polymer walls rather than at the interface, as might be expected. The void walls were shown to be an assembly of nanoparticle agglomerate shells that become embedded within the polymer. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1516–1525, 2010

PolyHIPEs are porous polymers synthesized within high internal phase emulsions (HIPEs). Recent research has shown that the locus of conventional free radical initiation (at the oil–water interface or in the organic phase) can affect the polyHIPE’s structure and properties. This paper is the first investigation of polyHIPE synthesis using activators generated by electron transfer for atom-transfer radical polymerization (AGET ATRP). Two different types of initiators (organic-phase-based and nanoparticle-based) were used to synthesize polyHIPEs within both surfactant-stabilized HIPEs and nanoparticle-stabilized Pickering HIPEs. The type and locus of initiation affected the macromolecular structure for all the polyHIPEs. Furthermore, the initiator also affected both the porous structure and the wall structure of polyHIPEs synthesized within Pickering HIPEs. Depending upon the initiator, either a polyhedral void shape or a nanoparticle assembly at the interface could become “locked in” at the very beginning of the polymerization.

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