Hydrogel foams are an important sub-class of macroporous hydrogels. They are commonly obtained by integrating closely-packed gas bubbles of 10–1000 μm into a continuous hydrogel network, leading to gas volume fractions of more than 70% in the wet state and close to 100% in the dried state. The resulting wet or dried three-dimensional architectures provide hydrogel foams with a wide range of useful properties, including very low densities, excellent absorption properties, a large surface-to-volume ratio or tuneable mechanical properties. At the same time, the hydrogel may provide biodegradability, bioabsorption, antifungal or antibacterial activity, or controlled drug delivery. The combination of these properties are increasingly exploited for a wide range of applications, including the biomedical, cosmetic or food sector. The successful formulation of a hydrogel foam from an initially liquid foam template raises many challenging scientific and technical questions at the interface of hydrogel and foam research. Goal of this review is to provide an overview of the key notions which need to be mastered and of the state of the art of this rapidly evolving field at the interface between chemistry and physics.

水凝胶泡沫是大孔水凝胶的一个重要子类。它们通常是通过将 10-1000 μm 的紧密堆积的气泡整合到连续的水凝胶网络中而获得的，导致湿状态下的气体体积分数超过 70%，干燥状态下接近 100%。由此产生的湿或干的三维结构为水凝胶泡沫提供了广泛的有用特性，包括非常低的密度、优异的吸收特性、大的表面积与体积比或可调节的机械特性。同时，水凝胶可提供生物降解性、生物吸收性、抗真菌或抗菌活性，或控制药物递送。这些特性的组合越来越多地用于广泛的应用，包括生物医学、化妆品或食品领域。从最初的液体泡沫模板成功配制水凝胶泡沫在水凝胶和泡沫研究的界面提出了许多具有挑战性的科学和技术问题。这篇综述的目标是概述需要掌握的关键概念以及化学和物理学之间这个快速发展的领域的最新技术。