Synthesis and Characterization of Ethylhydrosilicone Fluids as Liquid Cross-Linking Agents for the Encapsulant of Light Emitting Diodes

Abstract

We report a series of ethylhydrosilicone fluids synthesized through the ring-opening copolymerization of mixed cyclosiloxanes and end-capped with the 1,1,3,3-tetramethyl-1,3-dihydrosiloxane using anionic exchange resin as catalyst. The mixed cyclosiloxanes consisted of methylphenylcyclosiloxane (D_n ^Me,Ph, n = 3, 4), tetramethylhydrogencyclosiloxane (D₄ ^H), and tetramethylethylcyclosiloxane (D₄ ^Me,Et). The refractive indices of the obtained silicone fluids were determined, and these products were further characterized by SEC, ¹H NMR, TGA, and DSC. The DSC results indicated that the cold resistance of the silicone fluids obtained was improved with the increase of (MeEtSiO) unit content. Therefore, the silicone fluids with good cold resistance can be used as liquid cross-linking agents for LED encapsulants to enhance the cold tolerance of LED devices.

Keywords:

• Cross-linking agent
• encapsulant material
• ethylhydrosilicone fluid
• light emitting diode (LED)

This work was created with the financial support of the National High-Tech Research and Development Plan of China (Grant No. 2006AA03A134 and No. 2006AA050203-1) and Zhejiang Provincial Natural Science Foundation of China (Grant No. Y4080264).