One step preparation of porous polyurea by reaction of toluene diisocyanate with water and its characterization

Abstract

Porous polyurea (PPU) is prepared through a simple protocol by reacting toluene diisocyanate (TDI) with water in a binary solvent of water–acetone, and the process is optimized. Porosimetric tests demonstrate that PPU possesses typical properties of porous materials. The structure of the material is characterized by Fourier transform infrared (FTIR), NMR (¹H & ¹³C) and X-ray diffraction (XRD). FTIR analysis shows that TDI is fully reacted. Microstructure analysis of PPU by NMR reveals that PPU consists of short polyurea chains with a degree of polymerization about 15. The presence of crystallinity in PPU is confirmed by XRD, which shows three diffraction peaks, for which the corresponding chain conformations, based on interplanar spaces owing to different hydrogen-bonds, are depicted. TGA analysis demonstrates that PPU has high thermal stability, and no degradation is seen before 270 °C. The DSC test reveals that no obvious glass transition is observed owing to intensive hydrogen-bonding.