Preparation, microstructure, and property characterizations of fluorinated polyimide–organosilicate hybrids

Polyimide-silica sol–gel membranes from a novel alkoxysilane functionalized polyimide: preparation, characterization and gas separation properties

“…The second step, associated with the generalized aromatic polyimide degradation was the same for all hybrid membranes (500°C), showing that the presence of the inorganic component has no effect on the thermal stability of the polyimide under inert atmosphere. The residue at 850°C increased as expected with the increase of silica content [27]. The analysis of the residue in the thermograms recorded under oxygen atmosphere confirmed that the amounts of silica correspond to the theoretical values.…”

“…First, the stretching band for ArC-C bond appears as a wide band near 1,450 cm -1 , instead of the two well defined bands of PI-DABA25 and PI-Allyl spectra, indicating changes in the chemical environment around the aromatic structure after silylation. However, the band at 1,200 cm -1 , presumably associated to symmetric deformation of Si-CH 3 , and intense bands near 850 and 740 cm -1 associated with stretching vibration of Si-C bond [26], appear in all spectra, while the stretching bands for Si-O bonds in Si-O-Si and Si-O-C units, were overlapped with the stretching vibration of C-F bonds near 1,100 cm -1 [27]. Only the band at 470 cm -1 associated to stretching vibration of O-Si-O bond appeared in the PI-Si spectrum, being representative of the change in the pendant structure after modification with DMES.…”

“…The spectra exhibited, in addition, three silicon resonances, between -90 and -120 ppm attributed to the structural units Si(OH) 2 (O-Si) 2 (Q 2 ), Si(OH)(O-Si) 3 (Q 3 ) and Si(O) 4 -Si(Q 4 ) respectively [16,27]. Thus, even if the three-dimensional Si-O-Si network in the hybrid films was confirmed, the existence of Q 2 and Q 3 peaks indicated the presence of uncondensed species, which is in agreement with the silanol bands observed by FTIR.…”

Influence of atmospheric fluorine plasma treatment on thermal and dielectric properties of polyimide film

“…As a result, they have been extensively used in fields ranging from aerospace to microelectronics, optoelectronics, composites and fiber optics. Among these polymeric materials, polyimides are one of the well-known engineering plastics, offering excellent thermal, mechanical, dielectric and optical properties, along with good chemical resistance and high dimensional stability [1][2][3][4][5][6]. They are distinguished from other high-performance polymers by the solubility of their poly(amic acid) precursor form, which can be cast into uniform films and quantitatively converted to polyimide.…”

The influence of nanoadditives on surface, permeability and mechanical properties of self-organized organic–inorganic nanocomposite coatings

“…O-I polymeric nanocomposites can be formed by two basic methods: either by building-up the inorganic nanofiller in situ (using e.g., the sol-gel process) within the organic phase, or by homogeneous dispersion of previously prepared nanoparticles in the organic matrix, either in a ''finished'' polymer or in a polymerizable monomer(s). [1][2][3][4][5][6][7][8][9][10][11] Concerning nanofiller choice, all formations having at least one dimension in the sub-micrometer scale can be considered as nanoparticles. Typical representatives exceeding 2 nm dimensions are spherical particles, nanotubes and clays.…”