Synthesis And Application Of Karstedt Catalyst Used For Hydrosilylation

In this paper, Karstedt catalysts used for hydrosilylation were prepared and the performance of the catalysts was evaluated by no-flow time in cross-linking of silicon rubber and the activity for synthesis of polyether-grafted polyorganosiloxane (polyether silicon oil).According to Karstedt's patent, synthesized Karstedt catalysts at different conditions using chloroplatinic acid, divinyl tetramethyl siloxane, ethanol, sodium bicarbonate as reactants. The effects of the amount of NaHCO₃ and divinyl tetramethyl siloxane on the conversion of Pt and catalytic activity were discussed. The catalysts were characterized by FT-IR, ¹H-NMR, ¹³C-NMR. The no flow time between Karstedt catalysts and homogeneous catalyst in common use was compared. It reveals that catalytic activity of Karstedt catalysts is good at 100℃—120℃ and is much better than homogeneous catalyst in common use.In order to synthesize polyether-grafted polyorganosiloxane, silicon oil of low hydrogen content was firstly prepared by reacting hydrogen silicon oil with D₄. Hydrogen content was measured by chemical method. The product was characterized by FT-IR, ¹H-NMR and GPC.Polyether-grafted polyorganosiloxane was prepared by silicon oil of low content and vinyl terminated polyether under the catalysis by Karstedt catalyst. The reaction conditions, such as temperature, reaction time, the mode of polymerization, the amount of catalyst, the sequence of adding reactants, were discussed. The product was characterized by FT-IR, ¹H-NMR and GPC. It is found that polyether-grafted polyorganosiloxane can be prepared at low amount of Karstedt catalyst in short time.