Preparation and characterization of toughened polyurea aerogels incorporating linear long‐chain in the structure

Abstract

AbstractIn order to reduce the brittleness of polyurea (PUA) aerogel, reactive incorporation of linear long‐chain poly‐1,4‐butanediol bis(4‐aminobenzoate) (P1000) into PUA backbone was made by reacting mixed diamines with triisocyanates. The mixed diamines were composed of 4,4′‐diaminodiphenylmethane (MDA) and P1000. PUA aerogels were produced by freeze‐drying. The effect of P1000 percentage and solid content on the properties of PUA aerogel was investigated. It was found that the little addition of P1000 has a reinforcing and toughening effect on PUA aerogels, where the samples maintain a high extent of hydrogen bonding and low linear shrinkage, with a more compact and homogeneous microstructure. The resulting aerogels show apparent density between 0.05 and 0.18 g/cm3, surface area between 41 and 179 m2/g, and initial decomposition temperature of about 300°C. At 10% solid content and 15 mol % P1000 (in mixed diamines), the overall performance is optimal, with low apparent density (0.113 g/cm3), low thermal conductivity (0.021 W/m K), and high modulus (compressive modulus 7.4 MPa; flexural modulus 18.8 MPa).