Low Shrinkage and\nRobust Polyimide/Ultrafine Glass\nFiber Aerogel for Efficient Heat Resistance and Oil/Water Separation

Polyimide (PI) aerogels have attracted\na great deal of attention\ndue to their low density and excellent heat resistance. However, PI\naerogels produce large, irregular shrinkage during the thermal imidization\nprocess, resulting in decreased porosity and strength. In this work,\nthe silane coupling agent-modified ultrafine glass fibers (mUGF) were\nmixed with polyamide acid solution, followed by freeze-drying and\nthermal imidization to prepare PI/mUGF aerogels. As the inorganic\nreinforced phase, mUGF with a high aspect ratio can significantly\nenhance the skeleton of the PI aerogel, reducing its volume shrinkage\nand avoiding the collapse of the porous structure during thermal imidization.\nThe PI/mUGF aerogel exhibits low density (0.059 g/cm<sup>3</sup>),\nlow volume shrinkage (18%), good mechanical properties, and excellent\nthermal stability and insulation (thermal conductivity as low as 31.4\nmW/m·K at room temperature, 55.9 mW/m·K at 300 °C).\nAdditionally, the aerogel also shows excellent adsorption properties\n(pump oil at room temperature: 24 g/g; at 200 °C: 17 g/g) and\nstructural stability, which can be used to adsorb oils and organic\nsolvents from polluted water. These findings can promote the design\nand development of low-shrinkage and robust PI aerogels for oil/water\nseparation and thermal insulation.