双羟基Gemini表面活性剂的溶液性能及其聚集形态

Properties and Aggregation Morphology of Dihydroxyl Gemini Surfactants in Aqueous Solution

以1-溴十二烷、2-甲氨基乙醇、1,3-二溴丙烷、1,4-二溴丁烷、1,6-二溴己烷、1,8-二溴辛烷、1,10-二溴癸烷和1,12-二溴十二烷为原料,制得含有双羟基的Gemini表面活性剂〔缩写为12(OH)-s-12(OH),其中s=3、4、6、8、10和12〕。并测定了双羟基Gemini表面活性剂的热稳定性及其在水溶液中的表面张力及泡沫性能;采用耗散粒子动力学(DPD)方法预测了Gemini表面活性剂在水溶液中的聚集形态。结果表明,该类型Gemini表面活性剂具有较好的热稳定性和泡沫性能,随着连接基团长度的增加(s≤6),其在水溶液中的临界胶束浓度(CMC)从0.62mmol/L(s=3)降至0.21mmol/L(s=6)左右,且当连接基团长度s>6后CMC基本不变。随着Gemini表面活性剂摩尔分数的增加,胶束形态从球状胶束→棒状胶束→层状胶束→反胶束网络结构逐渐转变,且连接基团长度的改变几乎不影响其在水溶液中的胶束形态转变。

Gemini surfactants containing dihydroxy〔abbreviated as 12(OH)-s-12(OH),s=3,4,6,8,10 and12〕were synthesized using 1-bromododecane,2-methylaminoethanol,1,3-dibromopropane,1,4-dibromobutane,1,6-dibromohexane,1,8-dibromooctane,1,10-dibromodecane and 1,12-dibromododecane as raw materials.The thermal property of Gemini surfactants and their surface tensions in aqueous solution were characterized.Their foam properties were tested.The aggregation morphology of Gemini surfactants in aqueous solution was predicted by using dissipative particle dynamics(DPD).The results indicated that these Gemini surfactants had good thermal property and foaming property.With the increase of spacer length(s≤6),the critical micelle concentration(CMC)of Gemini surfactants in aqueous solution were decreased from 0.62 mmol/L(s=3)to about 0.21 mmol/L(s=6).The CMC almost kept unchanged when the spacer length further increased(s>6).When the molar fraction of Gemini surfactant increased,the micellar morphology gradually changed from spherical micelle to rod micelle to layered micelle eventually to reverse micelle network structure.Moreover,the change of spacer group length of the Gemini surfactants hardly affected the change of its micellar morphology in aqueous solution.