In this paper, a new type of soluble polyimide/silica (PI/SiO 2 ) hybrid was prepared by the sol-gel process. The coupling agent γ-glycidyloxypropyltrimethoxysilane (GOTMS) was chosen to enhance the compatibility between the polyimide (PI) and silica (SiO 2 ). Furthermore, the effects of the coupling agent on the morphologies and properties of the PI/SiO 2 hybrids were investigated using UV-vis and FTIR spectroscopies and SEM. The densities and solubilities of the PI/SiO 2 hybrids were also measured. The results show that the size of the silica particle was markedly reduced by the introduction of the coupling agent, which made the PI/SiO 2 hybrid films become transparent. The solubility of the PI/SiO 2 hybrid was also improved by the coupling agent. In addition, all of these effects became even more pronounced with increased amounts of the coupling agent. The thermal properties of the compatibilized PI/SiO 2 hybrids were investigated by DSC and TGA. Moreover, their mechanical properties were also characterized. The results showed that the glass transition temperatures (T g ) of the hybrids were higher than those of their counterparts without the coupling agent. The thermal stability was lowered by the addition of the coupling agent, but it was still higher than that of the pure polyimide. The compatibility of the two components was effectively improved by the coupling agent; this resulted in the markedly improved mechanical properties.
Improved performance of polymers, with respect to their mechanical and electrical properties for microelectronic applications, for example, can be obtained by introducing nanometer‐size inorganic particles into the polymer matrix. The preparation and properties—particularly the photolithographic ones—of hybrids of a photosensitive polyimide (shown in the Figure) and silica are reported for the first time.
Radiative lifetimes of 79 levels belonging to the 3d 3 4s4p, 3d 4 4p, 3d 3 4s5p, 3d 4 5p, and 3d 3 4s4d configurations of V i with energy from 26,604.807 to 46,862.786 cm −1 have been measured using time-resolved laser-induced fluorescence (TR-LIF) spectroscopy in laser-produced plasma. The lifetime values reported in this paper are in the range of 3.3-494 ns, and the uncertainties of these measurements are within ±10%. A good agreement was obtained with previous data. HFR+CPOL calculations have been performed and used to combine the calculated branching fractions with the available experimental lifetimes to determine semi-empirical transition probabilities for 784 V i transitions.
Radiative lifetimes of 27 levels (27 041.751–38 434.97 cm−1) in Gd I and 27 levels (27 130.397–45 394.925 cm−1) in Gd II have been measured using the time-resolved laser-induced fluorescence method. Laser ablation was used to generate Gd atoms and ions on a Gd plate. The measured lifetime values range from 4.0 to 90 ns with an uncertainty of 5% or less. Of all the results, to our knowledge, lifetimes of 23 Gd II levels and 11 Gd I levels are reported for the first time. Good agreement between our results and the previous ones has been achieved.
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