Preparing porous materials includes forming a mixture including a geopolymer resin and a liquid between which a nanoscale (1-1000 nm), microscale (1-1000 m), and/or milliscale (1-10 mm) phase separation occurs. The mixture is solidified (e.g., at an ambient temperature or a relatively low temperature), and a portion (e.g., a majority or a significant majority) of the liquid is removed from the solidified mixture. The liquid can include organic liquids from agricultural, geological, industrial, or household sources. The porous materials have accessible pores with a range of pore sizes including nanoscale pore sizes, microscale pore sizes, milliscale pore sizes, or a combination thereof. The porous material may be treated further to form another material, such as a composite.