Low‐Density Open Cellular Sponges as Functional Materials

Low‐density macroporous sponges with densities less than 100 mg cm−3 are both a challenge and an opportunity for advanced chemistry and material science. The challenge lies in the precise preparation of the sponges with property combinations that lead to novel applications. Bottom‐up and top‐down chemical and engineering methods for the preparation of sponges are a major focus of this Review, with an emphasis on carbon and polymer materials. The light weight, sustainability, breathability, special wetting characteristics, large mass transfer, mechanical stability, and large pore volume are typical characteristics of sponges made of advanced materials and could lead to novel applications. Some selected sponge properties and potential applications are discussed. Less is more: Low‐density macroporous sponges made of carbon or polymer materials offer an opportunity for advanced chemistry and materials science. The light weight, sustainability, breathability, special wetting characteristics, high mass transfer, mechanical stability, and large pore volumes of these materials suggest they may be “perfect” sponges. This Review critically addresses the status of the field along with opportunities and future directions.