Synthesis and property studies of methacrylate based poly(siloxane-silsesquioxane) resins
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Date
2016-04-01
Authors
Loh Tat Chuang
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Abstract
Nowadays, polysiloxane is widely used as optical lenses, optoelectronic
encapsulation and electronic packaging materials in electronic industry. Typical HB LEDs (high brightness light emitting diodes) is a potential lamp to replace existing incandescent, fluorescent and halogen bulbs. As for development of such high efficiency HB LEDs, the polysiloxane based LED encapsulation materials or lenses requires an excellent optical design, good heat dissipation, high refractive index for maximum light extraction efficiency and excellent light transmittance, as well as light resistance and high hardness to protect the LEDs from mechanical shock. However, most of the commercial silicone resin employed in LEDs encapsulation or packaging is known to have a refractive index range from 1.40 to 1.54 only, low hardness and poor thermal stability. In this research study, thermally stable and high refractive index (>1.55) methacrylate based poly(siloxane-silsesquixoane) (PSSQ) hybrid materials were fabricated and proposed as a potential material for optoelectronic and LEDs packaging materials. The methacrylate based PSSQ resins containing different portion of trisilanolphenyl-POSS were synthesized through condensation reaction, followed by the fabrication of these methacrylate based PSSQ hybrid material through hydrosilylation reaction. The chemical structure, molecular weight, optical properties and thermal properties were investigated by Fourier Transform Infrared (FTIR) Spectroscopy, 29Si-Nuclear Magnetic Resonance (NMR),
Gel Permeable Chromatography (GPC), Abbe refractometer, UV/Visible
Spectrophotometer, Thermomechanical Analyzer (TMA) and Thermogravimetric
Analyser (TGA). The FTIR spectra showed that the synthesized PSSQ resins have high degree of condensation. The fabricated PSSQ hybrid mateirals were shows excellent optical clarity, with light transmittance at least 96% over the wavelength 400 – 1000nm. The PSSQ hybrid material with higher POSS content gives higher hardness and higher refractive index (1.56). Similarly, PSSQ hybrid material with higher POSS content shown excellent thermal stability, high discoloration resistance at high temperature aging test, higher decomposition temperature, higher Tg and lower CTE.