Preparation and Characterization of Highly Cross-Linked Polyimide Aerogels Based on Polyimide Containing Trimethoxysilane Side Groups

Abstract

In this study, highly cross-linked and completely imidized polyimide aerogels were prepared from polyimide containing trimethoxysilane side groups, which was obtained as the condensation product of polyimide containing acid chloride side groups and 3-aminopropyltrimethoxysilane. After adding water and acid catalyst, the trimethoxysilane side groups hydrolyzed and condensed one another, and a continuous increase in the complex viscosities of the polyimide solutions with time was observed. The formed polyimide gels were dried by freeze-drying from tert-butyl alcohol to obtain polyimide aerogels, which consisted of a three-dimensional network of polyimide fibers tangled together. By varying the solution concentration of the polyimide containing trimethoxysilane side groups, polyimide aerogels with different densities (ranging from 0.19 to 0.42 g/cm(3)) were obtained. The resulting polyimide aerogels had small pore diameter (ranging from 20.7 to 58.3 nm), high surface area (ranging from 310 to 344 m(2)/g), high 5% weight loss temperature in air (at about 440 °C), and an excellent mechanical property. In addition, the glass transition temperature (349 °C) of the polyimide aerogels was much higher than that (210 °C) of the corresponding linear polyimide. So, even after being heated at 300 °C for 30 min, the porous structure of the polyimide aerogels was not completely destroyed.

Fiber Reinforced Polyimide Aerogel Composites with High Mechanical Strength for High Temperature Insulation

“…have reported a series of PI aerogels that were cross‐linked with polyamines and polyisocyanates, including 1,3,5‐triaminophenoxy benzene (TAB), octa‐(aminophenyl) silsesquioxane (OAPS), and 1,3,5‐benzenetricarbonyl trichloride (BTC) . Pei et al . utilized trimethoxysilane grafted onto PI side chains to obtain cross‐linked aerogels with small pore diameters, high surface areas, and excellent mechanical properties.…”

Fabrication and properties of anisotropic polyimide aerogels with aligned tube‐like pore structure

“…Polyimide (PI) is an important high‐performance material. Due to its rigid imide rings in macromolecular chains, PI has excellent thermal stability and mechanical performance, low dielectric constant, and outstanding chemical resistance . PI aerogel combines the properties of PI with porous structure of aerogel, exhibits excellent comprehensive performance such as mechanical property, thermal stability, fire resistance, chemical resistance, low dielectric constant, and so forth.…”

Anisotropic polyimide aerogels fabricated by directional freezing

“…However, their inherent fragility hinders their widespread applications in many fields; for example, in the aerospace field, excellent mechanical properties and a high thermal stability are both necessary. As a high‐performance material, polyimide (PI) has superior mechanical properties, outstanding resistance to solvents and radiation, an excellent thermal stability, and a low dielectric constant . Compared with silica aerogels, PI aerogels have better toughness.…”