A novel method is presented whereby the parameters quantifying the conductivity of an ionomer can be extracted from the phenomenon of electrode polarization in the dielectric loss and tan delta planes. Mobile ion concentrations and ion mobilities were determined for a poly(ethylene oxide)-based sulfonated ionomer with Li(+), Na(+), and Cs(+) cations. The validity of the model was confirmed by examining the effects of sample thickness and temperature. The Vogel-Fulcher-Tammann (VFT)-type temperature dependence of conductivity was found to arise from the Arrhenius dependence of ion concentration and VFT behavior of mobility. The ion concentration activation energy was found to be 25.2, 23.4, and 22.3+/-0.5 kJmol for ionomers containing Li(+), Na(+), and Cs(+), respectively. The theoretical binding energies were also calculated and found to be approximately 5 kJmol larger than the experimental activation energies, due to stabilization by coordination with polyethylene glycol segments. Surprisingly, the fraction of mobile ions was found to be very small, <0.004% of the cations in the Li(+) ionomer at 20 degrees C.

Plastics, with their ubiquitous presence in our daily lives and environment, pose an uncomfortable conundrum. Producers and consumers are aware of the value of these organic ingredients in material flow, yet their persistence and disruption to the ecological milieu desperately stipulate a shift in the status quo. Biodegradable plasticsas the name suggestshas its appeal in ensuring the safe return of carbon to ecosystems by complete assimilation of the degraded product as a food source for soil or aquatic microorganisms. However, despite more than a decade of commercial presence, these plastics are still far from replacing the demand for fossil-fuel-based commodity plastics. We discuss this apparent disconnect herein through a material value chain perspective. We review the current state of commercial biodegradable plastics and contrast it against the desired state of the zero-waste-focused circular economy. To close the gap, we suggest critical research needs concerning the structure and properties of biodegradable plastics, testing standards, application development, and waste management. The ultimate success in displacing conventional plastics with biodegradable alternatives will be predicated on collaboration between all stakeholders across the product value chain.

Nanoporous ceramic with a unique pore structure was derived from an all-hydrocarbon polymeric bicontinuous microemulsion (BmuE). The BmuE was designed to allow facile removal of one phase, resulting in a nanoporous polymer monolith with BmuE-like structure. The pores were filled with a commercially available, polymeric precursor to nonoxide, Si-based ceramics. Pyrolysis resulted in a monolith of nanoporous ceramic, stable to at least 1000 degrees C, with a BmuE-like pore structure. The pore structure is disordered and 3-D continuous. Microscopy and gas sorption measurements suggest a well-defined pore size distribution spanning roughly 60-100 nm, sizes previously unattainable through related techniques.

We demonstrate a universal approach to the synthesis of nanoporous materials with pore structures that are highly precise replications of bicontinuous microemulsions. The materials can be formed at both low and high temperature and have three-dimensionally continuous pore networks and pore sizes on the order of 100 nm.

Ternary blends of two homopolymers and a diblock copolymer can self-assemble into interpenetrating, three-dimensionally continuous networks with a characteristic length scale of B100 nm. In this review, we summarize our recent work demonstrating that these equilibrium fluid phases, known as polymeric bicontinuous microemulsions (BlE), can be designed as versatile precursors to nanoporous materials having pores with uniform sizes of B100 nm. As a model system, nanoporous polyethylene (PE) is derived from BlEs composed entirely of polyolefins. This monolithic material is then used as a template in the synthesis of other nanoporous materials for which structural control at the nm scale has traditionally been difficult to achieve. These materials, which include a high-temperature ceramic, polymeric thermosets and a conducting polymer, are produced by a simple nanocasting process, providing an inverse replica of the PE template. The PE is further used as a template for the production of hierarchically structured inorganic and polymeric materials by infiltration of mesostructured compounds into its pore network. The work described herein represents an unprecedented suite of nanoporous materials with well-defined pore structures prepared from a single PE template. They are anticipated to have potential application in diverse technological areas, including catalysis, separations and electronic devices.