A Study on the Interfacial Compatibility, Microstructure and Physico-Chemical Properties of Polyimide/Organically Modified Silica Nanocomposite Membrane

Abstract

Polyimide-silica (PI-Silica) composites are of tremendous research interest as high-performance materials because of their excellent thermal and mechanical properties and chemical resistance to organic solvents. Particularly, the sol-gel method of fabricating such composites is popular for manipulating their properties. In this work, PI-silica composite films are synthesized by the sol-gel method and thermal imidization from the solution mixtures of hydrolyzed tetraethoxysilane (TEOS) (or glycidoxypropyltrimethoxysilane (GPMS)) modified silica and an aromatic polyamic acid (PAA) based on 3,3′,4,4′-biphenyl tetracarboxylic dianhydride (BPDA)–p-phenylenediamine (PDA). The phase morphology of composites is found to be controlled by the substitution of TEOS with GPMS. Solid-state NMR spectroscopy is used to confirm the structural components of silica and GPMS-modified silica, whereas FT-IR results confirm the complete imidization of polyimide and composite film and suggest successful incorporation of Si–O–Si bonds into polyimide. The thermal, optical transmittance, and dielectric constant characterizations of pure polyimide and composite films are also carried out. Thermal stability of pure polyimide is found to be increased significantly by the addition of silica, whereas the partial substitution of TEOS with GPMS decreases the thermal stability of the composite, due to the presence of the alkyl organic segment of GPMS. The optical transmittance and dielectric constant of the composite films are controlled by manipulating the GPMS content.

Microstructures and dielectric properties of fluorene polyester ternary nanocomposites optimized by zero‐dimensional and two‐dimensional fillers

“…The absorption peak at 1742 cm −1 corresponds to the tensile vibration of the CO bond of the ester group in FPE, and the absorption peak at 1262 cm −1 corresponds to the tensile vibration of the CO bond 27 . The absorption peak at 1095 cm −1 is the antisymmetric tensile vibration of the SiOSi bond 37,38 while the peak pair at 800 cm −1 also corresponds to the vibration of the SiO bond 39,40 . In addition, from 1063 cm −1 to 723 cm −1 , with the increase in the composition of BNNS, it can be observed that the absorption peak gradually widens, which is caused by the stretching vibration of the BN bond.…”

“…27 The absorption peak at 1095 cm À1 is the antisymmetric tensile vibration of the Si O Si bond 37,38 while the peak pair at 800 cm À1 also corresponds to the vibration of the Si O bond. 39,40 In addition, from 1063 cm À1 to 723 cm À1 , with the increase in the composition of BNNS, it can be observed that the absorption peak gradually widens, which is caused by the stretching vibration of the B N bond. This can be good proof that SiO 2 nanoparticles and BNNS combine with the FPE matrix.…”

Microstructure and Electrical Properties of Fluorene Polyester Based Nanocomposite Dielectrics

“…Polymers have been widely used in electrical insulation [ 1 , 2 , 3 , 4 ], aerospace [ 5 , 6 , 7 , 8 ], energy storage [ 9 , 10 , 11 ] and other fields on account of their excellent electrical properties [ 12 , 13 , 14 ]. Limited by the low dielectric constant of pristine polymer and the poor corona resistance life, the application of polymers in some insulation or high- k fields is, however, restricted [ 15 , 16 , 17 ].…”

Effect of Extrusion Parameters on Short Fiber Alignment in Fused Filament Fabrication

“…Fillers and fibers are often added to polymers to improve their properties, either their stiffness and strength but also other properties like thermal stability [ 25 , 26 ]. While the impact of near spherical fillers such as glass beads or powders depends generally only on their content in the polymer, fibers have an anisotropic effect.…”