Disclosed herein are engineered composite materials suitable for applications that can benefit from a composite material capable of interacting with or responding to, in a controlled or pre-determined manner, changes in its surrounding environment, such as to attenuate a compression wave. The composite material generally includes a plurality of repeating units, with each repeating unit including a first layer of particles having a first mean diameter, and a second layer of particles having a second mean diameter, and an intermediary material that allows mobility of and contact between the first particles within the first layer and mobility of and contact between the second particles within the second layer; the contact allowing momentum transfer between the particles. The first mean diameter and second mean diameter are different and are less than 500 nm. The first or second particles may be core-shell particles having a core that is partly or completely filled with a liquid, a gas and/or a gel, such as a fire suppressant, a medically active agent or a dye.

Disclosed herein are engineered composite materials suitable for applications that can benefit from a composite material capable of interacting with or responding to, in a controlled or pre-determined manner, changes in its surrounding environment. The composite material is generally includes a gradient layer structure of a sequence of at, e.g., three or more gradient-contributing layers of microscale particles, wherein a mean particle size of particles of neighboring gradient-contributing layers in the cross section of the gradient layer structure varies from layer to layer, thereby forming a particle size gradient, and in contact with the gradient layer structure, a densely packed particle structure including densely packed microscale particles, wherein a mean particle size of the densely packed microscale particles does not form a particle size gradient in the cross section of the densely packed particle structure.

A variable transmission medium comprises a fluid and a plurality of nanoparticles dispersed in the fluid, wherein addition of acid to the fluid causes the nanoparticles to flocculate and form aggregates of particles that scatter light. The nanoparticles may comprise at least one metal oxide, such as titanium dioxide, zinc oxide or zirconium dioxide. The fluid may have a dielectric constant less than about 10. The medium may be used in, for example, privacy glass for a conference room.

Disclosed herein are engineered composite materials suitable for applications that can benefit from a composite material capable of interacting with or responding to, in a controlled or predetermined manner, changes in its surrounding environment. The composite material is generally comprised of a gradient layer structure of a sequence of at least three gradient-contributing layers of microscale particles, wherein a mean particle size of particles of neighboring gradient-contributing layers in the cross section of the gradient layer structure varies from layer to layer, thereby forming a particle size gradient, and in contact with the gradient layer structure, a densely packed particle structure including densely packed microscale particles, wherein a mean particle size of the densely packed microscale particles does not form a particle size gradient in the cross section of the densely packed particle structure.

A variable transmission medium comprises a fluid and a plurality of nanoparticles dispersed in the fluid, wherein addition of acid to the fluid causes the nanoparticles to flocculate and form aggregates of particles that scatter light. The nanoparticles may comprise at least one metal oxide, such as titanium dioxide, zinc oxide or zirconium dioxide. The fluid may have a dielectric constant less than about 10. The medium may be used in, for example, privacy glass for a conference room.

A variable transmission medium comprises a fluid and a plurality of nanoparticles dispersed in the fluid, wherein addition of acid to the fluid causes the nanoparticles to flocculate and form aggregates of particles that scatter light. The nanoparticles may comprise at least one metal oxide, such as titanium dioxide, zinc oxide or zirconium dioxide. The fluid may have a dielectric constant less than about 10.

An array structure includes a plurality of containers arranged in a predetermined pattern. Each container of the plurality of containers has a maximum outer dimension that is less than about 1 cm, and each container of the plurality of containers has a substantially predetermined porosity.