Synthesis and Characterization of UV-Curable Cross-Linked Carbazole Substituted Poly(Dimethylsiloxane) for Optoelectronic Encapsulant

This paper report the synthesis of a crosslink network of Carbazole substituted Poly (dimethylsiloxane). Vinyl Carbazole and Vinyl Trimethoxysilane were introduced into polydimethylsiloxane chain backbone through hydrosilylation reaction. 4-hydroxybutyl acrylate was then grafted into vinyl trimethoxysilane by condensation followed by UV curing to afford an elastomeric crosslink network. FTIR and 1H NMR spectroscopy were used to confirm the structure of the product as well as monitoring the progress of the reactions. The visual observation shows the changing appearance of the samples with increasing curing time and distance from UV exposure. The materials displayed refractive index between 1.407 1.452 which is within an acceptable range of application as electronic encapsulant. The crosslink network improved material hardness compared to that without. These properties were examined and thoroughly discussed within the scope of Lorentz-Lorenz model.

Synthesis and Thermal Stability of Cross-Linked Carbazole-Substituted Poly(dimethylsiloxane) for LED Encapsulation

A series of carbazole substituted poly (dimethylsiloxane) (PDMS) was synthesized by hydrosilylation reaction of 9-vinyl carbazole into PDMS structure. It was then cross-linked with vinyl trimethoxysilane by condensation reaction. The fabricated product display increasing in refractive index with increasing carbazole content. The higher carbazole content also produce high thermal stability which is suitable for electronic device encapsulation applications. The modification also increase Tg of the polymers displayed by differential scanning calorimetry analysis. This behavior owe much to the carbazole moeity when it was successfully incorporated into PDMS chain.

Thermodynamic and Kinetic Considerations - Effect of Organic Siloxane on MMA Polymerization

The effects of 3-(methacryloxypropyl)-trimethoxysilane (MATS) and vinyl trimethoxysilane (VTMOS) on methyl methacrylate (MMA) polymerization have been investigated. The two co-monomers appear to show opposite effects. The polymerization shows a higher rate of polymerization and extent of conversion in the presence of MATS than in its absence. However, a lower rate of polymerization and extent of conversion are obtained in the presence of VTMOS. The difference can be related to the different roles of the co-monomers. The increase in the rate of polymerization and conversion with MATS can be attributed to the higher reactivity of monomers. The lower conversion with VTMOS may be due to the electronic effects associated with VTMOS, which can decrease the electric density of the active double bond in MMA and therefore deactivate the polymerization. Further investigation shows that the change of free energy in the polymerization with MATS is lower than without MATS. Also, monomer reactivity in the presence of MATS is higher than in the absence of MATS. The decrease in free energy may be a thermodynamic response to the increase in the conversion. The increase in monomer reactivity may be responsible for increasing the rate of polymerization.