Colloidal particles can stabilize fluid interfaces in a manner similar to amphiphilic surfactants. A key difference however is that particles can become trapped at an interface with adsorption energies orders of magnitude greater than the thermal energy, kT, effectively �locking in� a non-equilibrium configuration of the fluid species. This phenomenon informs a robust bottom-up approach for synthesis of functional materials with higher-order structure using colloidal particles with tunable chemistry and geometry as building blocks. Familiar examples are particle-stabilized (Pickering) emulsions and foams, which are widely utilized in consumer products, oil recovery, foods, and pharmaceuticals. In this research, self-assembly of colloidal particles at fluid interfaces is used to direct the microstructure and functionality of a new class of porous and composite materials based on bicontinuous emulsions. Here, colloidal particles with specific wetting properties kinetically arrest spinodal decomposition of a partially-miscible liquid pair. The resultant non-equilibrium microstructure, known as a bijel, is then used as a general platform to synthesize a novel family of bicontinuous macroporous, hierarchically porous, and composite materials with tunable chemistry and morphology. The assembly of particles at the interface provides a means to percolate their properties in composite structures and generate hierarchical assemblies on widely separated length scales. Post-processing bijels to form functional materials is accomplished using several approaches, including electrodeposition, CVD, nanocasting, dealloying, or combinations thereof. This flexible, scalable, and inexpensive approach allows for the rational design of microstructured materials for diverse applications in catalysis, separations, tissue engineering, and renewable energy systems.

Exploiting nonequilibrium behavior in soft matter for the rational design of advanced materials

248th National Meeting (2014)

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