Synthesis Of A Novel Class Of Organosilicon Quaternary Ammonium Gemini Surfactants

Gemini surfactants are a special structure of a new generation of surfactants. It isa spacer group linking two amphiphilic structure, to overcome the hydrophobic force ofthe headgroup to enhance the hydrophobicity, which greatly improved the surfaceactivity. The most studied is the diquaternary ammonium, the effect of spacer andhydrophobic chain was in-depth studied. And silicone surfactant that has a bettersurface activity and spreading than commonly surfactant and can significantly reducewater surface tension to approximately21mN/m, is a kind of efficient surfactant.Organosilicon gemini surfactants have a more prominent advantages. To study the natureof organosilicon gemini surfactants is great for expanding the application of the siliconesurfactant in the interface surface, emulsion has a positive meaning.In this paper, a novel class of organosilicon quaternary gemini surfactants alkyl-α,ω-bis（diethyl-methyl-dimethoxy-silopropyl ammonium bromide）（α, ω=1,4;1,6;1,8）were synthesized with N, N-diethyl-aminopropyl-methyl-dimethoxysilane （NAPMDMS）and α, ω-alkylene-dihalide as the raw materials, where the NAPMDMS was synthesizedby reacting diethylamine with γ-chloropropylmethyldimethoxysilane （MCPS）. Theproperties of aqueous solution were measured with electrical conductivity, surfacetension and viscosity methods.The result are as follows:（1） Synthesis of N,N-diethyl-aminepropyl-methyl-dimethoxysilane. Diethylamine andMCPS in a molar ratio of1:4were mixed in an autoclave and stirred for20h at110℃under a N2stream. The final product was collected under vacuum distillation at10mmHgand80℃.（2） Synthesis of organosilicon diquaternary ammonium gemini surfactants. The result ofNMR and elemental analysis is Satisfactory.（3） The optimized methods of synthesis were detennined by discussing the factorsaffecting reactions. The optimal synthesis conditions: the reaction time of8h;the reaction temperature of80℃; the solvent of DMSO; the ratio of raw materials is2:1.（4） The CMC was measured by surface tension and electrical conductivity and found thatthe surface tension method is not suitable for [SiC₃-s-SiC₃]Br₂（s=4,6,8）. （5） Study the influence of different temperatures on surface activity of organosilicondiquaternary ammonium. Found that the higher the temperature, the higher of surfaceactivity， especially for the [SiC3-6-SiC3] Br2.（6） According to the （CMC） and surface tension data to calculate the amount of surfaceadsorption and molecular head area and found that [SiC3-6-SiC3] Br2adsorptioncapacity of less than [SiC₃-4-SiC₃]Br₂and [SiC₃-4-SiC₃]Br₂molecule head area of lessthan [SiC₃-6-SiC₃]Br₂.（7） Linear relationship between temperature and the CMC of organosilicon diquaternaryammonium（8） Ubbelohde viscometerto was used to determine the viscosity of the organosilicondiquaternary ammonium, the reduced specific viscosity of the specific viscosity wasobtained. The Viscosity size in the following order:[SiC₃-8-SiC₃]Br₂>[SiC₃-4-SiC₃]Br₂>[SiC₃-6-SiC₃]Br₂, The aggregates size in the following order:[SiC₃-8-SiC₃]Br₂>[SiC₃-4-SiC₃]Br₂>[SiC₃-6-SiC₃]Br₂. And that can be seen CMC ofthe organosilicon diquaternary ammonium is about20mmol/L, was in close agreementwith the result of electrical conductivity. According to the increased viscosity values canbe seen silicone quaternary ammonium salt to form more complex aggregates.