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Aminopropyl-silsesquioxane resins and thin films were synthesized from aminopropyltrimethoxysilane (APTMS). To investigate the changes in the molecular structure of the film with increasing curing temperature, Fourier transform infrared spectroscopy (FT-IR) was performed. The dielectric properties of the thin films were investigated by capacitance-voltage (C-V) measurements in a metal-insulator-semiconductor (MIS) structure. To explain the spectral changes in the FT-IR results, it is proposed that the Si-OH and aminopropyl groups freely exist without hydrogen bonding interactions in the curing temperature range 100-200°C, while molecular structures such as N(Si≡) 3 , N(Si≡) 2 , and O(Si≡) 2 are formed at higher temperatures in the range 250-300°C. The dielectric constant values and dissipation factors are regarded as being suitable for electronic applications, e.g., the gate insulators of organic thin film transistor (OTFT) devices. Interestingly, amphoteric charge trap behavior, such as a distinct clockwise C-V hysteresis, was observed in the sample cured at 300°C. It is proposed that this originates from the coexistence of N(Si≡) 2 and E′ centers in the cured films, into which positive charges or negative charges originating from the metal gate electrode are trapped, depending on the polarity of the applied electric field. It seems that the nitrogen-related molecular defects act as electron trap centers in the aminopropyl-silsesquioxane thin films.

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A series of methylene-biphenylene-bridged silsesquioxane thin films were synthesized from 4,4′-bis(trimethoxysilylmethyl)biphenyl (MBP) and methyltrimethoxysilane (MTMS) monomers at different molar ratios. A sol−gel process employing hydrolysis and condensation reactions was used to synthesize the precursors that were then spin-coated onto a silicon wafer. Optical properties of the thin films were investigated using spectroscopic ellipsometry (SE). Refractive index values increased from 1.40 for 0 mol % MBP to 1.60 for 100 mol % MBP. These are promising results for reliable encapsulants for a high-performance white light emitting diode (LED) given its high refractive index value and absence of epoxy moieties. The dielectric functions, consisting of real and imaginary parts closely related to refractive index and extinction coefficient, were also investigated. A new peak at 3.96 eV was observed for the 75 and 100 mol % MBPs in the imaginary dielectric functions, which was absent for the 25 and 50 mol % MBPs. The main origin for the new peak was thought to be the same as that for the peak at 4.67 eV, from the pseudo B1u ← A1 g transition of the six-membered ring constituting the biphenyl group. Herein, we suggest that the peak at 3.96 eV is generated from interactions between the biphenyl rings in the silsesquioxane materials, which can be explained by the local field correction and/or the planarization models.

Fire characteristics can be analyzed more realistically by using more accurate material properties related to the fire dynamics and one way to acquire these fire properties is to use one of the inverse property estimation techniques. In this study an optimization algorithm which is frequently applied for the inverse heat transfer problems is selected to demonstrate the procedure of obtaining fire properties of a solid charring material with relatively simple chemical structure. Thermal decomposition is occurred at the surface of the test plate by receiving the radiative energy from external heat sources and in this process the heat transfer through the test plate can be simplified by an unsteady one dimensional problem. The input parameters for the analyses are the surface temperature and mass loss rate of the char plate which are determined from the actual experiment of from the unsteady one-dimensional analysis with a given set of eight properties. The performance of hybrid genetic algorithm (HGA) is compare with a basic genetic algorithm (GA) in order to examine its performance. This comparison is carried out for the inverse property problem of estimating the fire properties related to the reaction pyrolysis of some relatively simple materials; redwood and red oak. Results show that the hybrid genetic algorithm has better performance in estimating the eight pyrolysis properties than the genetic algorithm.