物理化学学报
物理化學學報
물이화학학보
ACTA PHYSICO-CHIMICA SINICA
2009年
7期
1357-1361
,共5页
卢星宇%蒋艳%崔晓红%毛诗珍%刘买利%杜有如
盧星宇%蔣豔%崔曉紅%毛詩珍%劉買利%杜有如
로성우%장염%최효홍%모시진%류매리%두유여
表面活性剂%核磁共振%胶束形状转变%第二临界胶束浓度
錶麵活性劑%覈磁共振%膠束形狀轉變%第二臨界膠束濃度
표면활성제%핵자공진%효속형상전변%제이림계효속농도
Surfactant%NMR%Micelle shape transformation%critical micelle concentrationⅡ
运用核磁共振一维氢谱和自扩散实验方法研究了聚乙烯乙二醇异辛酚醚(TX-100)、十二烷基苯磺酸钠(SDBS)和十四烷基三甲基溴化铵(TTAB)三种不同类型的表面活性剂在重水溶液中的胶束形状转变,发现它们在临界胶束浓度以上的各自相应浓度都有胶束形状的变化(由球状转变为椭球状或棒状).在常温常压和没有其他添加剂的情况下,表而活性剂溶液浓度高于其临界胶束浓度时,球状胶束开始形成.核磁共振一维氢谱和自扩散实验的结果显示,当溶液浓度继续增加到一定程度时,溶液中表面活性剂分子的化学位移和自扩散系数的变化速率都有明显的转折,这说明溶液中球状胶束开始发生转变.进一步通过仔细分析对比核磁共振一维氢谱中各基团谱峰,发现表面活性剂胶束亲水表面上的质子的化学位移变化速率要远高于其疏水内核中的质子,据此推测胶束形状很可能由球状转变为椭球状或棒状.
運用覈磁共振一維氫譜和自擴散實驗方法研究瞭聚乙烯乙二醇異辛酚醚(TX-100)、十二烷基苯磺痠鈉(SDBS)和十四烷基三甲基溴化銨(TTAB)三種不同類型的錶麵活性劑在重水溶液中的膠束形狀轉變,髮現它們在臨界膠束濃度以上的各自相應濃度都有膠束形狀的變化(由毬狀轉變為橢毬狀或棒狀).在常溫常壓和沒有其他添加劑的情況下,錶而活性劑溶液濃度高于其臨界膠束濃度時,毬狀膠束開始形成.覈磁共振一維氫譜和自擴散實驗的結果顯示,噹溶液濃度繼續增加到一定程度時,溶液中錶麵活性劑分子的化學位移和自擴散繫數的變化速率都有明顯的轉摺,這說明溶液中毬狀膠束開始髮生轉變.進一步通過仔細分析對比覈磁共振一維氫譜中各基糰譜峰,髮現錶麵活性劑膠束親水錶麵上的質子的化學位移變化速率要遠高于其疏水內覈中的質子,據此推測膠束形狀很可能由毬狀轉變為橢毬狀或棒狀.
운용핵자공진일유경보화자확산실험방법연구료취을희을이순이신분미(TX-100)、십이완기분광산납(SDBS)화십사완기삼갑기추화안(TTAB)삼충불동류형적표면활성제재중수용액중적효속형상전변,발현타문재림계효속농도이상적각자상응농도도유효속형상적변화(유구상전변위타구상혹봉상).재상온상압화몰유기타첨가제적정황하,표이활성제용액농도고우기림계효속농도시,구상효속개시형성.핵자공진일유경보화자확산실험적결과현시,당용액농도계속증가도일정정도시,용액중표면활성제분자적화학위이화자확산계수적변화속솔도유명현적전절,저설명용액중구상효속개시발생전변.진일보통과자세분석대비핵자공진일유경보중각기단보봉,발현표면활성제효속친수표면상적질자적화학위이변화속솔요원고우기소수내핵중적질자,거차추측효속형상흔가능유구상전변위타구상혹봉상.
The micelle shape transformation of tert-octylpheny phenol polyethylene glycol ether(TX-100),sodium dodecyl benzene sulfonate(SDBS)and tetradecyl trimethyl ammonium bromide(TTAB)in heavy water solutions was studied by 1H nuclear magnetic resonance(NMR)spectroscopy,including an NMR self-diffusion experiment.These experiments showed that the surfactants formed several shapes of micelles(spherical,ellipsoidal,and rodlike)at the respective concentrations which were far above their critical micelle concentration(cmc).At ambient temperature,normal pressure and when the concentration of the surfactant was above the cmc without other additives,spherical micelles were formed.At higher surfactant concentrations,1H NMR spectra and self-diffusion experiments showed that abrupt changes occurred in their chemical shifts(δ)and in their self-diffusion coefficients(D).This indicated that spherical micelles transformed into larger micelles.By careful examination of every proton resonance peal in the 1H NMR spectra,we found that the protons near the head group experienced larger chemical shift changes than protons near the hydrophobic group.This suggests that the shape of surfactant micelles most likely transforms from spherical to ellipsoidal or rodlike.