Synthesis Of Polyether Grafted Polyhydrosiloxane And The Effect Of Crosslinks On The Performance

Polyether grafted polyhydrosiloxane is an organosilicone surfactant with excellent performance, so it is widely used in such areas as foam stabilizers for polyurethane foams, cosmetic materials, textiles, antifogging agents, additive in plastics, softening agents and so on. The addition reaction between organic silicons with Si-H bond and unsaturated compounds is called hydrosilylation reaction. The reaction is under mild condition with high yield, it is widely used to synthesize a variety of silicon polymers, it plays an important role in the chemistry of organic silicon. There are always crosslinks produced in the hydrosilylation reaction, it influences the performance of polyether grafted polyhydrosiloxane. In this thesis, the synthesis of polyether grafted polyhydrosiloxanes and the influences of the crosslinks on the performance of polyether grafted polysiloxane were studied. From reaction materials, the synthesis of polyhydrosiloxane, the synthesis of polyether grafted polyhydrosiloxane and the causes of crosslinks were studied. A series of polyether grafted polyhydrosiloxane with different crosslinks content were synthesized, the cloud point,surface tension of them were studied.In this thesis, polyhydrosiloxane was synthesized with octamethylcyclotetrasilo-xane and high hydrogen-containing polyhydrosiloxane as materials. The optimal conditions were obtained as follows:dosage of sulfuric acid is 1.5% of the whole materials, reaction time is 4h, reaction temperature is 65℃. A method which is used to determinate the hydrogen content and molecular weight by 1H-NMR with dioxane as standard is established.In this thesis, synthesis of polyether grafted polyhydrosiloxane was studied, it was synthesized with polyhydrosilxanes and polyether as materials and hexachloroplatinic acid as catalyst, the optimal conditions were obtained as follow: the dosage of catalyst is 55ppm, reaction time is 4h, reaction temperature is 110℃, the molar ratio of Si-H and polyether is 1 to 1.2.In this thesis, the causes of crosslinks were studied, it is found that crosslinks is mainly produced by polyhydrosiloxane in the hydrosilylation reaction and water is the most important factor to produce it. During the hydrosilylation reaction, a series of polyether grafted polyhydrosiloxane with different content of crosslinks were synthesized and the cloud point, surface tension of them were studied. It is found that the cloud point was reduced, the ablity to reduce surface tension was decreased with the existence of crosslinks. The existence of crosslinks may affect the cloud point and the surface tension of polyether grafted polyhydrosiloxane, so it should be minimized during the synthesis process.