Microphase separation regulation of polyurethane modified phenolic resin aerogel to enhance mechanical properties and thermal insulation

Applications of aerogels are commonly restricted by their complicated preparation route, high energy cost, brittleness and poor mechanical properties. Herein, a facile synthesis route for mechanical robust polyurethane (PU) modified phenolic resin (PF) aerogel was developed. The aerogel was prepared via polymerization of PU and phenolic resin (PF) followed by direct ambient pressure drying, sub-10 nm scale co-continuous phase structure was realized via control of kinetics of sol-gel reaction. The regulation of phase structure significantly enhanced mechanical properties of aerogels, which showed compressive strength and modulus of 29 MPa and 112 MPa, respectively, at 60 % strain without notable collapse. Furthermore, these aerogels showed excellent thermal insulation properties at both room temperature and high temperature. They exhibited superior dynamic ablative thermal protection at 1200 degrees C in oxygen-acetylene ablation test. This facile, inexpensive, environmentfriendly methodology for aerogel preparation expands the application scope of aerogels in the field of thermal insulation under harsh environments.