am8b20420_si_001.pdf (307.7 kB)
Increased Flexibility in Polyimide Aerogels Using Aliphatic Spacers in the Polymer Backbone
journal contribution
posted on 2019-02-22, 15:36 authored by Marcos Pantoja, Nicholas Boynton, Kevin A. Cavicchi, Bushara Dosa, Jessica L. Cashman, Mary Ann B. MeadorPolyimide aerogels
are mechanically strong porous solids with high
surface area, low density, and dielectric constants close to 1, making
them ideal materials for use as substrates for lightweight antennas.
Increasing the flexibility of the polyimide aerogels extends the usefulness
for conformal antennas for use on small aircraft such as unmanned
air vehicles or personal air mobility vehicles. To this end, polyimide
aerogels made with aromatic amines with 4–10 methylene units
as flexible spacers between aromatic rings in the backbone have been
fabricated. Substituting 25–75 mol % of fully aromatic 2,2′-dimethylbenzidine
with these flexible diamines increases the flexibility of polyimide
aerogels, making them bendable at thicknesses up to 2–3 mm.
The density, dielectric constants, thermal and moisture stability,
and mechanical properties of these aerogels were assessed to understand
the effect of the amount and length of the methylene spacers on these
properties.