羧甲基纤维素—十二烷基醇聚氧乙烯醚丙烯酸酯共聚物表面活性剂在水溶 …

采用动态激光光散射及环境扫描电镜研究了羧甲基纤维素型高分子表面活性剂在水溶液中的胶束形态。结果表明，共聚物在水溶液中的形态完全不同于羧甲基纤维素分子亲水疏水链段的引入，使共聚物分子聚集成了以疏水链段为核心的棍状胶束结构。高分子表面活性剂水溶液体系的归一化一级相关函数不符合单指数衰减，表明胶束形态的多分散性。在０．００５％￣１％浓度范围内，胶束粒大大小均分布的两个区域，随共聚物浓度增大，低粒径区保持     

羧甲基纤维素-十二烷基醇聚氧乙烯醚丙烯酸酯共聚物表面活性剂在水溶液中的胶束形态

采用动态激光光散射及环境扫描电镜研究了羧甲基纤维素型高分子表面活性剂在水溶液中的胶束形态 .结果表明 ,共聚物在水溶液中的形态完全不同于羧甲基纤维素分子 ,亲水疏水链段的引入 ,使共聚物分子聚集形成了以疏水链段为核心的棍状胶束结构 .高分子表面活性剂水溶液体系的归一化一级相关函数不符合单指数衰减 ,表明胶束形态的多分散性 .在 0 .0 0 5%～ 1 %浓度范围内 ,胶束粒子大小均分布在两个区域 ,随共聚物浓度增大 ,低粒径区保持在 3 0～ 1 0 0nm范围 ,为单分子区 ;而高粒径区随浓度增大移向更高值 ,表明多分子胶束不断长大 .     

PEO-PPO嵌段聚醚的聚集行为及其在药物载体领域的应用

聚氧乙烯-聚氧丙烯(PEO-PPO)嵌段聚醚是一类非离子型高分子表面活性剂,其结构具有很多独特之处:分子结构具有丰富的可设计性,强烈的温度依赖的胶束化行为以及溶剂选择的多样性,这些都极大丰富了其在溶液中自组装形成聚集体的研究内容。本文结合本课题组的工作着重综述了近期国内外有关线型和支状PEO-PPO嵌段聚醚在水溶液中聚集特性的研究进展,以及酸/碱、无机盐、醇类、小分子表面活性剂和聚合物等添加剂对其聚集行为的影响。PEO-PPO嵌段聚醚具有良好的生物相容性,在水溶液中能形成以PPO链段为疏水内核, PEO链段为亲水外壳的胶束结构,该结构非常适于作为疏水药物的载体。因此本文还综述了此类嵌段聚醚作为药物载体方面的研究成果,期望为药物剂型的开发研究提供理论支持。     

两亲性嵌段共聚物在选择性溶液中吸附行为的理论研究

通过自洽场理论方法研究了在圆形孔道以及水平基板受限情况下两亲性嵌段共聚物在选择性稀溶液中的自组装形态,考察受限管壁、管壁极性以及基板间距对聚合物吸附行为的影响.中性圆形孔道中,随着溶剂对疏水链的排斥作用增强和对亲水段的亲水作用增大,聚合物以蘑菇形状吸附于管壁上.疏水链、亲水链与溶剂的相互作用差异性越大,越容易产生吸附现象.在亲水性孔道中,吸附现象有所缓解,随着管壁对亲水段吸引作用的增强,聚合物在管壁附近形成规则排列的球状胶束.当疏水链、亲水链与溶剂的相互作用相差非常大时,即使管壁对亲水嵌段的吸附作用增强,也不能消除聚合物吸附现象.在中性水平基板中,随着基板间距的增加,两亲性嵌段共聚物在基板附近依次出现球状胶束-蘑菇状胶束-单层球状胶束-高分子刷-双层球状胶束-对称高分子刷的自组装形态.     

无规共聚物自组装球形胶束表面亲水性的耗散粒子动力学模拟

建立了含不同亲疏水粒子比的双亲性无规共聚物粗粒化模型. 采用耗散粒子动力学方法模拟了两亲性无规共聚物选择性溶剂自组装球形胶束表面的亲水性能. 模拟结果表明, 无规共聚物在选择性溶剂中自组装得到实心球形胶束, 球形胶束表面的亲水性与聚合物链亲水粒子含量、溶剂的选择性有关. 随着聚合物链所含亲水粒子增加, 球形胶束表面的亲水性增强. 球形胶束表面的亲水性随着疏水粒子与溶剂粒子间的排斥参数增大而增强, 模拟结果与实验结论一致. 该模拟方法给出的胶束微结构信息可以为双亲无规共聚物分子设计及自组装双亲胶束制备提供一定的理论指导.     

表面活性剂类多肽A6KA6K的自组装及机理研究

为了研究表面活性剂类多肽疏水链段长度及亲疏水氨基酸比例对其自组装结构的影响,本文设计了一种表面活性剂类多肽A6K的二倍体A6KA6K。圆二色谱分析表明的二级结构主要为无规卷曲结构并伴有少量的α-螺旋;透射电子显微镜和动态光散射分析表明,其在水溶液中能自组装形成纳米囊泡状结构。芘荧光分子探针研究表明自组装体存在疏水微区域将芘分子包裹在其中,证明了这种多肽在溶液中可形成胶束类的自组装体,并计算了其临界胶束浓度。相比已报道的表面活性剂类肽A6K,本文设计的肽序列A6KA6K由于在较长疏水链段区域中存在亲水性氨基酸K,对疏水相互作用有影响,使得含有14个氨基酸的肽自组装形成纳米囊泡状结构。     

光敏性无规-类接枝双亲聚合物的合成与自组装行为的研究

通过ε 己内酯改性丙烯酸酯 (FAn ,n =1～ 4 )与肉桂酰氯反应合成了一系列光敏性大单体 (FAnC ,n =1～ 4 ) ,以FAnC与甲基丙烯酸 (MAA)进行自由基聚合 ,制备具有光敏性的双亲无规 类接枝共聚物 (PMFAnC) .用红外光谱、凝胶渗透色谱、核磁共振和差示扫描量热仪等对共聚产物进行了表征 .双亲性PMFAnC可以在选择性溶剂中进行自组装 ,形成以PMFAnC中PFAnC疏水链段为核 ,PMAA亲水链段为壳的高分子胶束 .核内的肉桂酰基由紫外光引发发生光交联反应 ,得到具有稳定壳 核结构的胶束 .动态激光光散射、透射电子显微镜结果表明 ,PMFAnC在水溶液中形成了一定结构的光敏性纳米胶束 ,在紫外光照射下PMFAnC胶束内核发生光聚合反应使胶束粒径减小     

表面活性剂对污泥脱水性能影响的机理研究:Gemini表面活性剂与聚电解质相互作用的分子动力学模拟

表面活性剂可以与污泥表面的胞外聚合物(EPS)吸附形成胶束,释放出自由水和结合水,从而达到改善污泥脱水性能的目的.本文采用粗粒化的分子动力学模拟方法,研究了Gemini表面活性剂与EPS形成复合物的过程和结构.聚电解质链的亲疏水性对吸附过程有显著影响,亲水聚电解质链与Gemini表面活性剂吸附的主要驱动力为静电吸引,Gemini表面活性剂头基吸附在链上,尾链朝向溶剂;疏水聚电解质链与Gemini表面活性剂吸附过程由静电作用与疏水作用共同促进,Gemini表面活性剂以平行于聚电解质链的构型存在.Gemini表面活性剂联结基团长度对吸附过程的影响甚微;聚电解质链的电荷密度对亲水聚电解质链的吸附产生协同作用,对疏水聚电解质链的吸附不产生作用.     

烷基芳基磺酸盐的分子动力学模拟与自由能微扰计算

为研究不同结构的表面活性剂分子在溶液中胶束化能力的差异, 采用分子动力学方法模拟三种烷基芳基磺酸盐在真空和水溶液环境下的结构与相互作用. 利用自由能微扰(FEP)方法计算了水合自由能, 发现与用传统热力学表面张力法测定自制的烷基芳基磺酸盐结果一致. 研究表明: 烷基芳基磺酸盐在水溶液中的胶束化过程是自发进行的, 随着分子结构中芳环向长烷基链中间位置移动, 胶束化能力和胶束稳定性均下降; 疏水基周围水分子的“冰山结构”会影响胶束的稳定性, 而水分子中氢键的生存周期是反映冰山结构变化的重要指标; 同时, 亲水基与水分子间形成氢键的数目会增强或减弱分子脱离胶束体的趋势, 从而影响胶束结构的稳定性.     

水溶性高分子聚集行为荧光非辐射能量转移研究进展

评述了近几年荧光非辐射能量转移有疏水改性聚电解质的疏水聚集、高分子水溶液相变伴随的分子链塌陷、水溶性高分子与表面活性剂的相互作用等研究中的新进展,阐明了非辐射能量转移技术在水溶性高分子研究中的重要作用。     

高分子表面活性剂在固/液界面上的吸附形态

采用紫外光谱、XPS研究了羧甲基纤维素型高分子表面活性剂在硅胶 /水界面上的吸附形态 ,结果表明随着高分子表面活性剂溶液浓度增大 ,分子在硅胶表面的吸附由单层逐渐变为多层 ,生成半胶束结构 .     

CMC系列高分子表面活性剂与原油超低界面张力形成机理的研究

采用动态激光光散射及环境扫描电镜研究了羧甲基纤维素系列高分子表面活性剂与大庆原油形成超低界面张力的机理.结果表明,CMC系列高分子表面活性剂具有与低分子量表面活性剂相比拟的表/界面活性,其水溶液的表面张力可达2835mN/m,界面张力达到10^-110mN/m.碱的加入可显著降低高分子表面活性剂与原油的界面张力,在适当条件下界面张力达到超低值(10^-3mN/m),可望作为三次采油的驱油剂.等效烷烃模型研究表明,用碱与原油酸性组分的作用来解释碱能使界面张力下降至超低值的传统观点是不完善的,加入碱能使高分子表面活性剂胶束解缔,胶束数量增多,胶束粒径减小,单分子自由链增加,有利于高分子表面活性剂向界面迁移和排布,这是高分子表面活性剂和碱复配体系与原油界面张力下降至超低值的主要原因.     

Micellar shape change and internal segregation induced by chemical modification of a tryptych block copolymer surfactant

We report the detailed characterization of micelles formed by two nonionic, amphiphilic ABC triblock copolymers. Poly(ethylene oxide)-b-poly(styrene)-b-1,2-poly(butadiene) (PEO-b-PS-b-PB) triblock copolymer "OSB" forms core-corona spherical micelles in aqueous solution, and the two hydrophobic blocks S and B are mixed homogeneously within the micelle core. PEO-b-PS-b-PB:C6F13I triblock copolymer "OSF" was prepared by selective fluorination of the B block in OSB with n-perfluorohexyl iodide. Fluorination of the B block induces internal segregation into an inner F core and an intermediate S shell. Furthermore, the strong incompatibility that results from fluorination drives a shape change into an oblate ellipsoid. These micellar morphologies are confirmed by combined light, neutron, and X-ray scattering measurements, as well as TEM imaging.     

The Effects of Salts and Ionic Surfactants on the Micellar Structure of Tri‐Block Copolymer PEO‐PPO‐PEO in Aqueous Solution

The micelles of two poly(ethylene oxide)‐poly(propylene oxide)‐poly(ethylene oxide) (PEO‐PPO‐PEO) block copolymers, P123 and F127 (same mol wt of PPO but different % PEO) in aqueous solution in the absence and presence of salts as well as ionic surfactants were mainly examined by dynamic light scattering (DLS). The study is further supported by cloud point and viscosity measurements. The change in cloud point (CP), as well as the size of micelles in aqueous solution in presence of salts obeys the Hofmeister lyotropic series. Addition of both cationic cetylpyridinium chloride (CPC) and anionic sodium dodecylsulfate (SDS) surfactants in the aqueous solution of P123 show initial decrease of micellar size from 20 nm to nearly 7 nm and then increasing with a double relaxation mode, further in the presence of NaCl this double relaxation mode vanishes. The effect of surfactant on F127, which has much bigger hydrophilic part is different than P123 and have no double relaxation. The relaxation time distributions is obtained using the Laplace inversion routine REPES. Two relaxation modes for P123 are explained on the bases of Pluronic rich mixed micelles containing ionic surfactants and the other smaller, predominantly surfactant rich micelles domains.     

Influence of a hydrophobic diol on the micellar transitions of Pluronic P85 in aqueous solution

Micellization behavior of an amphiphilic ethylene oxide-propylene oxide-ethylene oxide tri-block copolymer Pluronic P85 [(EO)(26)(PO)(39)-(EO)(26)] in aqueous solution and in the presence of a hydrophobic C(14)diol (also known as Surfynol104) was examined by physico-chemical methods such as viscometry, cloud point (CP) and scattering techniques viz. dynamic light scattering (DLS) and small angle neutron scattering (SANS). The addition of diol decreases the cloud point and gelation temperature of aqueous Pluronic P85 copolymer solution. DLS and SANS measurements of the polymer in aqueous solution indicated micellar growth and sphere to rod transition in the presence of diol. Surfynol 104 is a sparingly water soluble diol surfactant with a solubility of approximately 0.1 wt%. However, up on addition to Pluronic solution, diol gets incorporated in the block copolymer micelles and leads to structural transition of the micelles. An increase in the temperature and the presence of added sodium chloride in the solution further enhances this effect. The addition of hydrophobic C(14)diol increases the hydrodynamic size and aggregation numbers of the micellar system. The micellar parameters for the copolymer in the presence of C(14)diol are reported at different temperatures and added sodium chloride concentrations.     

Shape transformation of poly(butadiene)‐b‐poly(ethyleneoxide) plus DTAB compound micelles in aqueous solutions

The micellar shape of Poly(butadiene)‐b‐poly(ethyleneoxide) (PB‐PEO) plus Dodecyltrimethylammoniumbromide (DTAB) compound micelles was investigated by light scattering, small‐angle X‐ray scattering and small‐angle neutron scattering in dependence of the molar ratio between block copolymer and surfactant. The given block copolymer forms cylindrical micelles in binary aqueous solution, which transform to spherical aggregates upon the addition of a sufficiently high amount of DTAB. It is interesting to note that the micellar shape seems to be a bistable feature, in the sense that it depends not only on the molar ratio of BCP and DTAB but also in a predictable manner on the preparation procedure of the solution.     

Capillary flow behavior of worm‐like micelles studied by small‐angle X‐ray scattering and small angle light scattering

A novel capillary flow device has been developed and applied to study the orientation of worm‐like micelles, among other systems. Small‐angle X‐ray scattering (SAXS) data from micelles formed by a Pluronic block copolymer in aqueous salt solution provides evidence for the formation of worm‐like micelles, which align under flow. A transition from a rod‐like form factor to a less persistent conformation is observed under flow. Flow alignment of worm‐like micelles formed by the low molar mass amphiphile system cetyl pyridinium chloride+sodium salicylate is studied for comparative purposes. Here, inhomogenous flow at the micron scale is revealed by streaks in the small‐angle light scattering pattern perpendicular to the flow direction. Copyright © 2006 John Wiley & Sons, Ltd.     

羧甲基纤维素系列高分子表面活性剂形成微乳液的研究

采用紫外光谱、相图、动态激光光散射、同位素示踪、光学显微镜、电导率等研究了羧甲基纤维素系列高分子表面活性剂与甲苯-水-异丙醇体系微乳液的形成过程,发现微乳液粒子大小均一,形态一致,其尺寸比低分子表面活性剂所形成的微乳液粒子大得多.醇分子插入到油水界面,改变了两相界面结构,促使微乳液的生成.电导率测定表明所形成的微乳液区均为水包油结构,即使在富含甲苯区域,亦不会有油包水的反相胶束形成.     

Effect of SDS on the self-assembly behavior of the PEO-PPO-PEO triblock copolymer (EO)20(PO)70(EO)20

The mixed micellar system comprising the poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide)-based triblock copolymer (EO)(20)(PO)(70)(EO)(20) (P123) and the anionic surfactant sodium dodecyl sulfate (SDS) has been investigated in aqueous media by small-angle neutron scattering (SANS) and viscosity measurements. The aggregation number of the copolymer in the micelles decreases upon addition of SDS, but a simultaneous enhancement in the degree of micellar hydration leads to a significant increase in the micellar volume fraction at a fixed copolymer concentration. This enhancement in the micellar hydration leads to a marked increase in the stability of the micellar gel phase until it is destroyed at very high SDS concentration. Mixed micellar systems with low and intermediate SDS concentrations form the micellar gel phase in much wider temperature and copolymer concentration ranges than the pure copolymer micellar solution. A comparison of the observed results with those for the copolymers (EO)(26)(PO)(40)(EO)(26) (P85) and (EO)(99)(PO)(70)(EO)(99) (F127) suggests that the composition of the copolymers plays a significant role in determining the influence of SDS on the gelation characteristics of the aqueous copolymer solutions. Copolymers with high PO/EO ratios show an enhancement in the stability of the gel phase, whereas copolymers with low PO/EO ratios show a deterioration of the same in the presence of SDS.