Synthesis, characterization and thermal properties of novel PMDA-PAPD/silica hybrid network polymers

Abstract

Novel PMDA-PAPD/silica hybrid polymers were synthesized by the sol-gel process. Fourier transform infrared spectroscopy and 29Si nuclear magnetic resonance spectroscopy were used to characterize the structure of the hybrids, (condensed siloxane bonds designated as Q1, Q2, Q3, Q4, wth 3-aminopropyltriethoxysilane having mono-, di-, tri-, tetra-substituted siloxane bonds is designated as T1, T2 and T3). The results revealed that Q3, Q4 and T3 are the major microstructure elements in forming a network structure. The surface morphology, particle size, crystallinity and the thermal stability of the hybrids were investigated using Scanning electron microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray diffraction (XRD), Thermogravimetric analysis (TGA) and Differential Scanning Calorimetry (DSC). SEM and TEM revealed that the hybrids were nanocomposites. The XRD indicated that covalent bonding (Si-O-Si) between the organic and inorganic components enhanced miscibility. DSC and TGA results showed that these hybrid materials had excellent thermal stability. The heat capacities of some materials were reported for the temperature range 273 K and 363 K as no thermal anomaly was found in this temperature range.