Polyimide Cellulose Nanocrystal Composite Aerogels

Abstract

Cellulose nanocrystals derived from\ntunicates (<i>t</i>-CNC) were used as a reinforcing nanofiller\nfor polyimide aerogels.\nTwo sets of polyimide aerogels, containing either 2,2′-dimethyl­benzidine\n(DMBZ) or 4,4′-oxydianiline (ODA) and 3,3′,4,4′-biphenyl­tetracarboxylic\nacid dianhydride (BPDA) cross-linked with 1,3,5-tris­(4-amino­phenoxy)­benzene\n(TAB), were studied. Total solids composition of the aerogels were\nkept constant at 7.5 wt %, with 0–13.33 wt % of the total solids\nbeing the carboxylic acid-functionalized <i>t</i>-CNC (<i>t</i>-CNC–COOH) filler. The incorporation of the <i>t</i>-CNC–COOH, with carboxylic acid content of either\n560 or 920 mmol/kg, in the polyimide aerogel networks improved both\nphysical and mechanical properties of the final materials. Isothermal\naging of <i>t</i>-CNC–COOH aerogel composites was\nalso conducted at 150 and 200 °C for 24 h. Higher content <i>t</i>-CNC–COOH/polyimide aerogels showed less change\nin their density and reduced shrinkage during aging, which further\nemphasized the effect of the <i>t</i>-CNC–COOH reinforcement\nin retaining the structural integrity of the aerogel.