【作者】 李新；

【导师】 郝京诚；

【作者基本信息】 山东大学 ， 物理化学， 2008， 博士

【摘要】 表面活性剂在溶液中可以自发聚集形成多种多样的聚集体,如球状、棒状、碟状、蠕虫状胶束、囊泡和溶致液晶等。表面活性剂的诸多用途,如增溶、乳化、微反应器等都与表面活性剂聚集体的结构和性质密切相关。表面活性剂混合体系中形成的聚集体一直是表面活性剂研究的热点内容,改变表面活性剂的组成或比例,就可以改变或调整聚集体的结构和性质,表面活性剂混合体系在技术层面更有利用价值。本文对不同链长碳氢/碳氟表面活性剂的复配体系和非离子碳氢表面活性剂/氨基改性聚硅氧烷（硅表面活性剂）复配体系在水溶液中聚集体的形成、结构和性质进行了系统研究。论文的具体内容如下:1不同链长碳氢/碳氟表面活性剂的复配体系研究1.1体系之一:C₁₂DMAO/C₇F₁₅CF=CHCOOH（T=25.0±0.1℃）100 mM十二烷基二甲基氧化胺(C₁₂DMAO)胶束溶液中加入高Krafft点的碳氟表面活性剂C₇F₁₅CF=CHCOOH,构筑了碳氢/碳氟表面活性剂的复配体系,对混合水溶液的相行为、有序聚集体的形成、结构和性质进行了详细的研究。结果表明:混合液体系具有复杂的相行为,在碳氟表面活性剂浓度为50 mM时,形成粒径呈多分散的单层囊泡相;低于该浓度,混合体系将经历由蠕虫状胶束到单层囊泡相的转变。相行为、流变性质、DLS、Cryo-TEM、¹H、¹⁹F NMR及IR等手段的研究表明:碳氢表面活性剂C₁₂DMAO与碳氟表面活性剂C₇F₁₅CF=CHCOOH形成阴/阳离子对C₁₂DMAOH⁺—^-OOCCH=CFC₇F₁₅,该结构是理解混合体系聚集体形成、结构和性质的关键。1.2体系之二:C₁₄DMAO/C₇F₁₅CF=CHCOOH（T=25.0±0.1℃）100mM十四烷基二甲基氧化胺(C₁₄DMAO)溶液加入少量碳氟表面活性剂C₇F₁₅CF=CHCOOH,溶液中聚集体的大小和分散度就发生了明显的改变。在碳氟表面活性剂浓度为10mM时,混合液体系为两种尺寸分布的胶束溶液;当碳氟表面活性剂浓度为50mM时,溶液中观察到了两种尺寸分布的囊泡相。该结果表明虽然碳氢表面活性剂C₁₄DMAO与碳氟表面活性剂C₇F₁₅CF=CHCOOH形成阴阳离子对C₁₄DMAOH⁺—^-OOCCH=CFC₇F₁₅,但由于碳氟链与碳氢链的较弱的相互作用,混合液中形成了两种组成分布的聚集体:一种以碳氢表面活性剂为主,粒径较小;一种以碳氟表面活性剂为主,粒径较大。这种互疏现象随疏水链长的增加、表面活性剂浓度的增加表现更为显著。1.3体系之三:C₁₆DMAO/C₇F₁₅CF=CHCOOH体系（T=60.0±0.1℃）100mM十六烷基二甲基氧化胺(C₁₆DMAO)胶束溶液中（T=60.0±0.1℃）,加入10mM碳氟表面活性剂C₇F₁₅CF=CHCOOH,相行为观察表明混合液中形成了囊泡相。相对于短链的C₁₂DMAO和C₁₄DMAO而言,加入较少量的C₇F₁₅CF=CHCOOH就可诱导C₁₆DMAO胶束向囊泡相的转变,这说明:随着碳氢表面活性剂同系物碳链长度的增加,分子堆积参数（P=V/al）增大,碳氢/碳氟表面活性剂混合体系更倾向于形成囊泡相。2非离子碳氢表面活性剂/氨基改性聚硅氧烷体系（T=25.0±0.1℃）10wt%聚氧乙烯—5异十三醇醚(iso-C₁₃E₅)多层囊泡相溶液或10 wt%Iso-C₁₃E₅/C₄E₂（聚氧乙烯—2正丁醇醚）（1:1,重量百分比）碟状胶束相溶液,加入不同量的（0—20 wt%）氨基改性聚硅氧烷（即“氨基硅油”）,相行为研究表明:在一定浓度区域内形成了无色透明氨基硅油微乳液。所形成微乳液的内相为非离子表面活性剂和氨基改性聚硅氧烷形成的聚集体。相行为、流变性质及Cryo-TEM的研究表明氨基改性聚硅氧烷的构象受其浓度、其它表面活性剂的种类以及浓度的影响。形成无色透明氨基硅油微乳液的首要条件是控制氨基改性聚硅氧烷构象,使氨基硅油与其它表面活性剂或添加剂形成的聚集体大小小于50nm。更多还原

【Abstract】 Surfactants can self-assemble to form many kinds of aggregates in aqueous solutions such as sphere、rod-like、disk-like or worm-like micelles,vesicles,lamellas.It is the structure and property of the aggregates that determine the performance of surfactants. For example the function of volatilization,emulsion and micro-reactor is connected with the architecture of the aggregates of surfactants in solution.The aggregates in mixed surfactants are much more fascinating.For only by changing the composition or the ratio between surfactants,we can adjust the morphology and property,of aggregates,acquiring idea performance which has more meaning for technical application.Several surfactant systems in aqueous solutions are studied in this paper and the results are summarized as following:1.Different length hydrogenated surfactant/fluorinated surfactant system1.1 C₁₂DMAO/C₇F₁₅CF=CHCOOH system（T=25.0±0.1℃）C₇F₁₅CF=CHCOOH is almost insoluble in water at room temperature and has a Krafft point higher than room temperature.Mixing it into 100mM C₁₂DMAO （dodecyldimethylamine oxide）solution we obtained CH/CF cationic/anionic （catanionic）surfactant system.The phase behavior,structure and property of the aggregates in the mixed surfactant solution were investigated.The results showed that the mixed solution has complex phase behavior.Unilamellar vesicles with a broad distribution formed when the concentration of fluorinated surfactant is at 50 mM. Below this concentration the mixed surfactant system experienced the transformation between worm-like micelle and unilamellar vesicle.Study by phase behavior, rheology measurement,DLS,Cryo-TEM,¹H、¹⁹FNMR and IR shows that the fluorinated surfactant C₇F₁₅CF=CHCOOH and hydrogenated surfactant C₁₂DMAO forms anionic/cationic ionic C₁₂DMAOH⁺-^-OOCCH=CFC₇F₁₅through the hydrophilical heads.The combined structure is helpful to understand the mechanism, structure and properties for the self-assembly aggregation of the salt-free CH/CF catanionic surfactant systems.1.2 C₁₄DMAO/C₇F₁₅CF=CHCOOH systems（T=25.0±0.1℃） The size and size distribution of the aggregates in 100mM C₁₄DMAO （tetradecyldimethylamine oxide）solution changed dramatically when a small quantity of fluorinated surfactant C₇F₁₅CF=CHCOOH was put into it.When the concentration of fluorinated surfactant was at 10 mM,two modules of size distribution of micelles were obtained.When the concentration of fluorinated surfactant was at 50 mM two modules of size distribution of vesicles were observed.The results demonstrate that although the elecstatic combines the hydrophilic heads of the two kinds of surfactants together,the weak interaction of the hydrophobic parts of hydrogenated and fluorinated surfactants leads aggregates with two kinds of compositions formed in mixed CH/CF surfactant system:one of aggregate is rich in hydrogenated surfactant, and another is rich in fluorinated surfactant.It can be concluded that the demixing phenomenon between hydrogenated and fluorinated surfactants will be enhanced when the length of hydrogenated surfactant tail increases or the concentration of the surfactants increases.1.3 C₁₆DMAO/C₇F₁₅CF=CHCOOH systems（T=60.0℃±0.1℃）Vesicle phase formed when 10 mM C₇F₁₅CF=CHCOOH mixed with 100 mM C₁₆DMAO（hexadecyldimethylamine oxide）.Since molecular packing parameter （p=V/al）for the mixed surfactants increases,mixed hydrogenated and fluorinated surfactants have more tendency to form Lα-phase.2 Non-ionic surfactant/amino modified polysiloxane system（T=25.0±0.1℃） When 10wt%iso-C₁₃E₅（isotridecylalkohol-5EO）solution（multilamellar vesicle phase） or 10 wt%iso-C₁₃E₅/C₄E₂（wt%/wt%,1:1）（diethylenglykolmonobutylether）solution （disk-like micelle phase）mixed with up to 20%amino modified polydimethylsiloxane （silicone surfactant）,transparent microemulsion of amino silicone oil formed at some concentration domain.The droplet dispersed in the microemulsion is actually the aggregates of nonionic surfactants and positive charged amino modified polysiloxane. The structure and properties of self-assembled aggregates were observed through phase behavior,Cryo-TEM,and rheological measurements.It is suggested that the conformation of amino modified polysiloxane changes with its concentration in the mixed surfactant system.And the conformation of amino modified polysiloxane is influenced by its concentration and co-existed surfactants.It is concluded that the key to form transparent microemulsion of amino silicone oil is to control the conformation of amino modified polysiloxane so that the aggregates of amino silicone oil and other surfactants is no bigger than 50 nm.更多还原