Aerobijels: Ultralight Carbon Monoliths from Cocontinuous Emulsions

Bijels are used to develop a new class of ultralight hierarchically porous aerogels exhibiting multimodal porosity across multiple length scales. Through in situ functionalization of a particle‐laden liquid interface wherein binary liquid pairs are kinetically trapped out of equilibrium through interfacial jamming, monolithic and freestanding carbon electrodes are produced with prescribed bulk densities down to ≈2 mg cm^?3. Exemplary electrokinetic experiments indicate that the bicontinuity of the pore structure is essential for enhancing transport to and from the active electrode surfaces, demonstrating that these materials possess a superior ability to accumulate and transport charge when compared to analogous systems with restricted pore connectivity and fluid throughput. This approach offers a new synthetic route to bicontinuous and hierarchical aerogel materials with nested multimodal porosities. The flexibility of this scheme can address critical issues related to transport‐limited behaviors that arise in many technological fields, ranging from energy and catalysis research to remediation and sensing applications.     

Cover Picture:Transparent Zeolite–Polymer Hybrid Materials with Adaptable Properties (Adv. Funct. Mater. 14/2007)

On p. 2298, Gion Calzaferri and co‐workers of the University of Bern, Switzerland report on a new, simple preparation procedure for highly transparent zeolite‐polymer hybrid materials and polymer covered zeolite L monolayers. The thus‐obtained new transparent host–guest inorganic–organic hybrid materials offer fascinating novel possibilities for the development of optical devices such as lenses, special mirrors, filters, polarizer, grids, optical storage devices, and windows. We report here on a simple preparation procedure for highly transparent zeolite‐polymer hybrid materials and polymer covered zeolite L monolayers. Wrapping up zeolites containing, e.g., dye molecules as guest species with alkoxysilane derivatives results in an efficient dispersion of the nano particles into the organic liquid monomer. The following copolymerisation process leads to a hard, insoluble and transparent material containing zeolites. Optical properties such as colour, luminescence, refractive index or photochromism can be adapted by simply changing the type and amount of the guest in the zeolite crystals, while transparency is maintained.     

Porous Structures: In situ Porous Structures: A Unique Polymer Erosion Mechanism in Biodegradable Dipeptide‐Based Polyphosphazene and Polyester Blends Producing Matrices for Regenerative Engineering (Adv. Funct. Mater. 17/2010)

Synthetic biodegradable polymers serve as temporary substrates that accommodate cell infiltration and tissue in‐growth in regenerative medicine. To allow tissue in‐growth and nutrient transport, traditional three‐dimensional (3D) scaffolds must be prefabricated with an interconnected porous structure. Here we demonstrated for the first time a unique polymer erosion process through which polymer matrices evolve from a solid coherent film to an assemblage of microspheres with an interconnected 3D porous structure. This polymer system was developed on the highly versatile platform of polyphosphazene‐polyester blends. Co‐substituting a polyphosphazene backbone with both hydrophilic glycylglycine dipeptide and hydrophobic 4‐phenylphenoxy group generated a polymer with strong hydrogen bonding capacity. Rapid hydrolysis of the polyester component permitted the formation of 3D void space filled with self‐assembled polyphosphazene spheres. Characterization of such self‐assembled porous structures revealed macropores (10–100 μm) between spheres as well as micro‐ and nanopores on the sphere surface. A similar degradation pattern was confirmed in vivo using a rat subcutaneous implantation model. 12 weeks of implantation resulted in an interconnected porous structure with 82–87% porosity. Cell infiltration and collagen tissue in‐growth between microspheres observed by histology confirmed the formation of an in situ 3D interconnected porous structure. It was determined that the in situ porous structure resulted from unique hydrogen bonding in the blend promoting a three‐stage degradation mechanism. The robust tissue in‐growth of this dynamic pore forming scaffold attests to the utility of this system as a new strategy in regenerative medicine for developing solid matrices that balance degradation with tissue formation.