Synthesis And Properties Of Modified Branched Silicone Emulsifier

Silicone surfactants have excellent emulsifying ability.However,when they are applied in cosmetics or other fields,which uses the mixture of silicone oil,hydrocarbon and grease as the oil phase,the emulsified droplets still can't maintain long-term stability.Therefore,in this thesis,novel silicone surfactants were prepared by modifying th esilicone oil with hydrophilic chain,branched-silicone,and alkylane.These surfactants shown excellent emulsifying ability to oil phase which composed of silicone oil,hydrocarbon and grease.The main contents are as follows:The vinyltris(trimethylsiloxy)silane(hereafter refered as branched-silane)was prepared by using the triethoxyvinylsilane and ethoxytrimethylsilane.Then,the modified silicone emulsifier was synthesized through hydrolysilation reaction,which used hydrogen silicone oil(PMHS),vinyltris(trimethylsiloxy)silane,allyl polyther and 1-dodecene as raw material.The structure of modified silicone was characterized by ~1H NMR and FIT-IR infrared spectrum.Single factor experiments orthogonal experiment showed that the optimal conditions for prepareation of the modified silicone emulsifier was:reaction temperature T=95 ~oC,reaction time t=5 h,the dosage of catalyst was 20 ppm,n(Si-H):n(C=C content of the mixture)=1:1.1.Its conversion rate was 94.97%.The prepared silicone emulsifiers were used to prepared the water-in-oil emulsion,and the effect of molecular structure and oil phase composition on the emulsifying ability of the emulsifier was invesitigated.The branched-silicone grafted to the silicone chain can enhance the emulsifying ability of silicone emulsifier to silicone oil,and the graftion of alkyl group can improve the emulsifying ability of silicone emulsifier for hydrocarbon.The modified 0.3%PMHS emulsifier with HLB=5,the hydrophobic group graft ratio is n(branched silane):n(alkyl)=25:75,has best emulsifying ability for preparation of the stable W/Si,W/O,W/Si+O emulsion.In addition,when 1%NaCl and 8%1,3 butanediol were added to the aqueous phase of the emulsion,the interfacial tension of the oil and water would decrease rapidly,and the initial particle size of the emulsion would decreas to 4.45±0.32?m.The allylchloro-polyglycery-3 was synthesized by using the allyl glycidyl ether and diglycerin as raw materials.Then,PMHS was modified with branched silane,allyl triglycerol and 1-dodecene to prepare the modified silicone emulsifier.The structure of prepared silicone emulsifier was characterized by infrared.Single factor experimental response surface analysis showed the optimal experimental conditions was:reaction temperature T=92.1°C,reaction tme t=5.08 h,the dosage of catalyst is21.69 ppm,the material ratio is n(Si-H):n(C=C)=1:1.03.The product conversion rate was 92.94%.The effect of emulsifier structure,oil-water ratio and emulsifier dosage on emulsion stability was studied,it was found that when the emulsifier HLB 2.5~5.0 and SLB 2.5~5.0,the stable W/Si and W/O emulsion could be prepared.When the water phase volume of the water-in-oil emulsion accounts for 80%(V/V)and the amount of emulsifier is 5%of the water phase,the water-in-oil emulsion with smallest droplet size of 3.91±0.16?m could be prepared.