Preparation, characterization and application of polyether and long-chain alkyl co-modified polydimethylsiloxane

In this paper, by using a self-made hydrogen-containing polymethylhydrogensiloxane having a hydrogen content of 0.20%, a polyether of F-6 and α-olefin having a carbon chain length of even numbers in 6–18 as main raw materials, polyether and long-chain alkyl co-modified polydimethylsiloxane having different molecular structures were successfully prepared via hydrosilylation reactions. ¹H-NMR, TGA, DLS, fluorescence spectroscopy and surface tension measurements were used to characterize their structures and properties. The results shows that when the molar ratio of polyether to α-olefin is 5:1, an emulsion type anti-foaming agent with polyether and long-chain alkyl co-modified polydimethylsiloxane as active ingredient was successfully prepared, it basically maintains 90% quality at 300 °C, indicating good heat resistance, and the critical micelle concentration (CMC) of polyether and long-chain alkyl co-modified polydimethylsiloxane is 8.55 mg/L. The surfactant has good dilution stability compared to other small molecule. When the hydrophilic-lipophilic balance (HLB) is equal to 10, the compound emulsifier is made of Span 80 and Tween 80, the emulsification method is a phase inversion method, and the obtained emulsion has the smallest particle size and an average particle diameter of 134.4 nm, the emulsion shows good stability and uniformity, and the particle size distribution is narrow. In summary, the polyether and long-chain alkyl co-modified polydimethylsiloxane synthesized in this work have potential applications in the fields of anti-foaming agent.