Ting, Kuang-Min;Xu, Jun;Guo, Bao-Hua published 《A novel vacuum-assisted method for fabricating flexible polyimide foams from 3,3′,4,4′-oxydiphthalic anhydride/4,4′-oxydianiline》 in 2017. The article was appeared in 《High Performance Polymers》. They have made some progress in their research.HPLC of Formula: 2657-87-6 The article mentions the following:
In this research, a novel method for fabricating flexible polyimide foams was developed. The foam was derived from the precursor synthesized via esterification of 3,3′,4,4′-oxydiphthalic anhydride and 4,4′-oxydianiline. After drying process, the remaining solvent acted as blowing agent. By adjusting the synthesis condition, low-mol. weight precursor was obtained and can be foamed under environment temperature With this novel type of precursor and vacuum-assisted foaming process, we could easily obtain any shape of foams, which was easy to process under relatively low temperature The foam could be imidized later in order to improve mech. strength. During the imidization process, in situ Fourier transform IR (FTIR) anal. was applied to analyze the variation of the imidization percentage with time. The d. of the foams could be adjusted from 12 to 30 kg m-3 with uniform cell structure. Other properties of foams were also investigated. The glass transition temperature of the precursor was 70°C, which is obviously lower than that of the usual previously reported. The 5% and 10% weight loss temperatures of the finally imidized foam can reach up to 567°C and 593°C, resp. The foams belong to open cell structure with 98% open cell content. The limiting oxygen index of the foams varied from 38.6 to 41.9, depending on foam densities. The compressive strength of the foam ranged from 30.6 to 90.6 kPa when the d. changed from 15 to 28 kg m-3. In addition, the in situ FTIR anal. was applied to analyze the imidization percentage of the foam during imidization process.3-(4-Aminophenoxy)aniline (cas: 2657-87-6) were involved in the experimental procedure.
3-(4-Aminophenoxy)aniline is one of ethers-buliding-blocks. Ethers lack the hydroxyl groups of alcohols. Without the strongly polarized O―H bond, ether molecules cannot engage in hydrogen bonding with each other. HPLC of Formula: 2657-87-6Ethers do have nonbonding electron pairs on their oxygen atoms, however, and they can form hydrogen bonds with other molecules (alcohols, amines, etc.) that have O―H or N―H bonds.
Reference:
Ether – Wikipedia,
Ether | (C2H5)2O – PubChem