  We present examples of bicontinuous interfacially jammed emulsion gels
("bijels") with a designed gradient in the channel size along the sample. These
samples are created by quenching binary fluids which have a gradient in
particle concentration along the sample, since the channel size is determined
by the local particle concentration. A gradient in local particle concentration
is achieved using a two-stage loading process, with different particle volume
fractions in each stage. Confocal microscopy and image analysis were used to
quantitatively measure the channel size of the bijels. Bijels with a gradient
in channel size of up to 2.8%/mm have been created. Such tailored soft
materials could act as templates for energy materials optimised for both high
ionic transport rates (high power) and high interfacial area (high energy
density), potentially making them useful in novel energy applications.

Soft Condensed Matter