苯甲醇对CTAB/KBr胶束体系流变性及CTAB分子1HNMR谱影响的研究

报道了苯甲醇对CTAB/KBr胶束体系粘度的影响,利用1HNMR法研究了苯甲醇在CTAB胶束中的增溶位置.结果表明,在KBr盐溶液中,随着苯甲醇的加入,0.01mol/LCTAB胶束体系的粘度增大至最大值.对CTAB分子的1HNMR分析表明,少量的苯甲醇增溶在棒状胶束的界面,促使胶束体积增大和相互缠结,体系的粘度随之增大;当苯甲醇浓度较高时,将增溶在胶束的栅栏层靠近极性头一侧,胶束发生棒-球转变和解缠,体系的粘度降低.     

胶束溶液增溶过程的高分辩NMR研究

本文用高分辨~1H-NMR谱, 研究了十二烷基硫酸钠(SDS)胶束水溶液对m-二甲苯和苯甲醇的增溶作用。结果表明, 增溶物浓度很低时, m-二甲苯和苯甲醇均吸附在胶束-水“界面”。随着浓度增加m-二甲苯增溶在胶束的“栅栏”层和内核中, 并沿SDS的烃链均匀分布。当浓度约为0.34摩尔分数时, 它沿烃链的增溶达到“饱和”, 开始进入胶束内核中心。苯甲醇主要增溶在“栅栏”层中, 其羟基靠近胶束-水“界面”, 苯基深入到与α-CH_2基相邻的五个亚甲基的位置。     

苯甲醇对CTAB／KBr胶束体系流变性及CTAB分子^H NMR谱 …

报道了苯甲醇对ＣＴＡＢ／ＫＢｒ胶束体系粘度的影响,利用＾１Ｈ ＮＭＲ法研究了苯甲醇在ＣＴＡＢ胶束中的增溶位置。结果表明,在ＫＢｒ盐溶液中,随着苯甲醇的加入,０．０１ｍｏｌ／Ｌ ＣＴＡＢ胶束体系的粘度增大至最大值。     

不同类型表面活性剂对苯甲醇的增溶作用

本文采用高分辨核磁共振方法，考察了苯甲醇在三种类型表面活性剂胶束中的增溶作用。 现，无论是在两性表面活性剂Ｃ１２ＢＥ，还是在阴离子表面活性剂ＳＤＳ和阳离子表面活性剂ＤＴＡＢ胶束中，苯甲醇均增溶在胶束与水的界面层和胶束栅栏层。     

分子动力学模拟研究荧光分子芘在磺基甜菜碱胶束中的增溶

采用分子动力学模拟研究了荧光分子芘在磺基甜菜碱两性表面活性剂聚集体中的增溶现象．结果表明,芘分子自发地自溶液中增溶进入胶束疏水内核的栅栏层区域．当胶束溶液中芘分子的局部浓度增大时,两个芘分子可以同时增溶进胶束的栅栏层区域,此时两个芘分子形成π-π共轭堆积的激发态络合物．但是由于荧光分子之间的弱兀．兀相互作用,激发态络合物在胶束中是不稳定的,表现为两个芘分子的多次结合和分离．模拟表明,分子动力学方法可以在分子水平上研究荧光探针分子在表面活性剂胶束中的增溶位点,解释荧光分子在胶束中的动力学现象．     

表面活性剂溶胀胶束：性能及应用

溶胀胶束是表面活性剂胶束增溶其它物质后使胶束膨胀的一种胶束状态,因其能显著提高难溶性物质的溶解度而备受关注。针对近年来对溶胀胶束的研究进展,综述了溶胀胶束的最大增溶量、增溶过程以及增溶后形貌尺寸的变化等问题,总结了影响胶束增溶作用的因素,厘清了溶胀胶束与微乳液的异同,介绍了溶胀胶束的应用,展望了其应用前景与发展方向。     

水相胶束体系中底物微环境对辣根过氧化物酶催化反应的影响

利用荧光测活法比较了HRP在有机相与水相胶束体系中催化不同芳香胺类的动力学常数,发现在水相胶束体系中,HRP是在一个较严格的亲、疏水界面进行催化反应。同时对界面酶学性质进行了初步研究,讨论了在胶束中不同增溶位置对反应动力学常数的影响。     

1H NMR及Raman光谱法研究十二烷基甜菜碱缔合体系的微观结构

采用＾１ＨＮＭＲ法研究了十二烷基甜菜碱,苯甲醇,水形成胶束的微观结构,推测苯甲醇在胶束中的增溶位置,发现在由Ｏ／Ｗ向Ｗ／Ｏ型的转变过程中存在过渡结构,其分子排列有序,光学上呈向向同性,称之为拟液晶结构。     

水溶液中表面活性剂月桂醇聚氧乙烯醚硫酸钠性能的介观模拟

采用介观动力学模拟方法MesoDyn研究比较了表面活性剂月桂醇聚氧乙烯醚硫酸钠(AES)和月桂醇硫酸钠(SDS)在水溶液里的聚集行为及相互间作用, 从介观层面上研究了分子结构差异所导致聚集行为的一系列差别. 同时模拟研究了AES/苯体系中各组分对体系形貌的影响. 以苯、正辛醇为油污代表, 通过对密度切片图的研究, 模拟比较了AES对这两种油污去除机理的差异. 选择AES/苯为研究体系, 从介观的层次考察其胶束形成的影响因素. 结果表明, 由于极性头的结构差别, AES和SDS在临界胶束浓度和聚集数方面都有差异, 同时两种表面活性剂之间又存在着较强的协同效应. 除疏水性作用、氢键作用外, 亲水性作用也在胶束形成中起重要作用. 对密度切片图的观察得出, 由于所选择油污的结构差异导致了AES对其增溶方式的差异.     

偶氮氯磷—mA—二苯胍—溴化十六烷基吡啶四元络合物光度法测定岩矿中微量铈组稀土

自发现表面活性剂具有“胶束增溶”作用、可大大提高多元络合物光度法的分析灵敏度后,表面活性剂用于多元络合物的光度测定便日趋增多。本实验较系统地研究和制定了以偶氮氯磷—mA(CPA—mA)为显色剂、二苯胍(DPG)为协同增色剂(第二配位体)、溴化十六烷基吡啶(CPB)为胶束增溶表面活性剂,在一定条件下与铈组     

Pluronic嵌段共聚物F127和P123胶束对萘、蒽、芘的增溶

35℃时F127和P123在ccm后可生成内核PO成分分别为92.7%和94.5%的胶束,后者胶束内核体积为前者的2.8倍.稠环芳烃和空胶束的第一步缔合平衡常数K₁值均随萘、蒽、芘顺序逐渐增大.萘、蒽、芘在每个F127和P123胶束中的增溶量均随胶束内核体积增大而线性增加,每个PO基团对应的增溶量比十二烷基磺酸胶束内核中相同体积对应的增溶量约大近2倍.Pluronic胶束除与稠环芳烃间具有强相互作用力外,所形成的大内核是导致大增溶量的重要因素.     

Micelles from PEO-PPO-PEO block copolymers as nanocontainers for solubilization of a poorly water soluble drug hydrochlorothiazide

The effect of molecular characteristics of EO-PO triblock copolymers viz. Pluronic(?) P103 (EO(17)PO(60)PEO(17)), P123 (EO(19)PO(69)EO(19)), and F127 (EO(100)PO(65)EO(100)) on micellar behavior and solubilization of a diuretic drug, hydrochlorothiazide (HCT) was investigated. The critical micellization temperatures (CMTs) and size for empty as well as drug loaded micelles are reported. The CMTs and micelle size depended on the hydrophobicity and molecular weight of the copolymer; a decrease in CMT and increase in size was observed on solubilization. The solubilization of the drug hydrochlorothiazide (HCT) in the block copolymer nanoaggregates at different temperatures (28, 37, 45°C), pH (3.7, 5.0, 6.7) and in the presence of added salt (NaCl) was monitored by using UV-vis spectroscopy and solubility data were used to calculate the solubilization characteristics; micelle-water partition coefficient (P) and thermodynamic parameters of solubilization viz. Gibbs free energy (ΔG(s)°), enthalpy (ΔH(s)°) and entropy (ΔS(s)°). The solubility of the drug in copolymer increases with the trend: P103>P123>F127. The solubilized drug decreased the cloud point (CP) of copolymers. Results show that the drug solubility increases in the presence of salt but significantly enhances with the increase in the temperature and at a lower pH in which drug remains in the non-ionized form.     

Microenvironment in the corona region of triblock copolymer micelles: temperature dependent solvation and rotational relaxation dynamics of coumarin dyes

Dynamic Stokes' shift and fluorescence anisotropy measurements using coumarin-153 (C153) and coumarin-151 (C151) as the fluorescence probes have been carried out in aqueous poly(ethylene oxide)20-poly(propylene oxide)70-poly(ethylene oxide)20 (P123) and poly(ethylene oxide)100-poly(propylene oxide)70-poly(ethylene oxide)100 (F127) block copolymer micelles with an aim to understand the water structures and dynamics in the micellar corona region. It has been established that the probes reside in the micellar corona region. It is indicated that the corona regions of P123 and F127 micelles are relatively less hydrated than the Palisade layers of neutral micelles like Triton-X-100 and Brij-35. From the appraisal of total Stokes' shift values for the probes in the two block copolymer micelles, it is inferred that the F127 micelle is more hydrated than the P123 micelle. It is observed that the dynamic Stokes' shift values for both of the probes remain more or less similar at all the temperatures studied in the P123 micelle. For C153 in F127, however, the observed Stokes' shift is seen to decrease quite sharply with temperature, though it remains quite similar for C151. Moreover, the fraction of the unobserved initial dynamic Stokes' shift is appreciably higher for both the probes in the F127 micelle compared to that in P123. Over the studied temperature range of 293-313 K, the spectral shift correlation function is described adequately by a bi-exponential function. Rotational relaxation times for C153 in both the micelles show a kind of transition at around 303 K. These results have been rationalized assuming collapse of the poly(ethylene oxide) (PEO) blocks and formation of water clusters in the corona region due to dehydration of poly(ethylene oxide) blocks with an increase in temperature. A dissimilar probe location has been inferred for the differences in the results with C153 and C151 probes in F127. Comparison of the microviscosity and the hydration of the block copolymer micelles has also been made with those of the other commonly used neutral micelles, for a better understanding of the results in the block copolymer micelles.     

Mixed micelles of binary triblock polymer mixtures in pure water at 30 °C

This is the first report on the mixed micelles of binary triblock polymer (TBP) mixtures. The steady-state fluorescence and viscosity measurements have been carried out for the various binary combinations of TBP (i.e., P103 + F127/P84/L64/P104/P123) in pure water at 30 °C. All the TBP components selected for the study show clear micelle formation process. The pyrene fluorescence has been used to determine the critical micelle concentration. As micelle-forming TBP can also be termed as nonionic surfactants; therefore, their mixed micelle formation has been evaluated by applying the regular solution theory. It has been observed that this theory very well predicts the nature of mixed micelles. The P103 + F127/P84/L64 binary mixtures undergo mixed micelle formation due to the synergistic interactions while P103 + P104/P123 show antagonistic behavior. The results clearly show that the mixtures with greater number of poly(ethylene oxide) units undergo favorable mixing.     

Study of micellar and phase separation behavior of mixed systems of triblock polymers

Cyclic voltammetric (CV) techniques have been employed to study the mixed micellar behavior of binary mixtures of triblock polymers (TBP) such as F127+P85, F127+P85, F88+P85, and F88+P123 using 2,2,6,6-tetramethyl-1-piperidinyloxy (Tempo) as an electroactive probe. Critical micellar concentration (cmc) has been obtained for pure triblock polymers and their mixed systems from the plots of peak current (i_p) variation versus the total concentration. Diffusion coefficients of the electroactive species have been determined from the Randles–Sevcik equation. The interaction parameter (β) for the mixed micelles was obtained from the regular solution theory. The values of β suggest that the synergism does exist especially with the F88+P123 system. Cloud point measurements have also been made on the binary mixtures of triblock polymers following similar mixing criteria. An effort has been made to correlate the micellar behavior and phase separation (cloud point) phenomenon. From the correlation, it can be concluded that in the systems studied, an increase in cmc increases the cloud point of mixed systems of triblock polymers.     

Pluronic嵌段共聚物F127胶团对布洛芬的增溶(英文)

研究了PluronicF127胶团溶液对药物布洛芬(IBU)的增溶作用.通过芘探针荧光法测定了不同温度下F127在水溶液和0.01mo·lL-1pH7.4磷酸盐缓冲生理(PBS)溶液中的临界胶束浓度(cmc),采用高效液相色谱(HPLC)测定了F127溶液中布洛芬的溶解度,并依据公式计算了增溶参数(摩尔增溶量c和胶团-水分配系数K),考察了温度、溶剂和F68的加入对F127胶团化行为及其对布洛芬增溶作用的影响.结果表明:布洛芬的溶解度随F127质量分数的提高线性增加;随着温度升高,cmc急剧下降,胶团内核的疏水性增强,χ和K稍有增大;与水溶液相比,在PBS溶液中cmc减小,χ几乎不变,K显著降低;F68的加入对F127胶团的性质几乎无影响,对增溶的影响也不明显.对增溶参数的分析表明,K反映的是药物布洛芬的性质,χ则可反映嵌段共聚物F127的溶解效能,并证实了布洛芬是通过F127胶团的内核和栅栏层而实现增溶的.     

Micellization and gelation of mixed copolymers P123 and F127 in aqueous solution

The micellization in dilute aqueous solution of Pluronic copolymers P123 (E21P67E21) and F127 (E98P67E98) and mixtures of the two was investigated using static and dynamic light scattering. Gelation of concentrated solutions of the two copolymers and their mixtures was studied using tube inversion and oscillatory rheometry. The two copolymers comicellized to give micelles with narrow size distributions. Clouding temperatures and critical micelle temperatures decreased as the proportion of P123 in the mixture was increased. Micelle association numbers of the mixed micelles lay between the values found for micelles of P123 and F127 alone, whereas micelle radii passed through maximum values in the range 0-50 wt % P123. As judged by the ratio of the thermodynamic to the hydrodynamic radius, the micelle interaction potential changes gradually from soft to hard as the proportion of P123 in the mixture is increased. Regions of cubic and hexagonal (birefringent) gel were defined for concentrated solutions. The high-temperature boundary of the 30 wt % cubic gel decreased monotonically from 90 to 43 degrees C as the proportion of P123 in the mixture was increased from 0 to 100 wt %, whereas the low-temperature boundary was essentially constant at 15 +/- 3 degrees C. Increasing the proportion of P123 in the mixture at 25 degrees C increased the concentration at which the cubic gel was first formed and decreased the concentration at which the hexagonal gel was first formed.     

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.     

Studies on the Interactions Between Genistein and Copolymer F127

In this paper, the interactions of an isoflavone molecule, Genistein (Gen), with Pluronic F127 at different pH values have been investigated using laser light scattering techniques, film analysis methods, UV-vis spectroscopy and transmission electron microscopy. The TEM images and the DSL studies indicate the formation of a Gen/F127 complex induced by the solubilization of Gen in micelles, and the stability of the Gen/F127 complex decreases with the increase of pH. At pH of 6.4, the turbidity of the Gen/F127 complex solution is significantly reduced in the presence of 0.31 mol⋅L⁻¹ ethylene glycol, indicating the existence of hydrogen bonds between Gen and the F127 copolymer. Experiments on controlled release demonstrate that Gen-loaded F127 micelles act as a drug carrier, giving slow release to the surrounding solution over a period of time. Rapid release can be triggered by increasing the pH of the micelle solutions     

Adsorption and structural properties of channel-like and cage-like organosilicas

Channel-like and cage-like mesoporous silicas, SBA-15 (P6mm symmetry group) and SBA-16 (Im3m symmetry group), were modified by introducing single ureidopropyl surface groups, mixed ureidopropyl and mercaptopropyl surface groups, and single bis(propyl)disulfide bridging groups. These hexagonal and cubic organosilicas were prepared under acidic conditions via co-condensation of tetraethyl orthosilicate (TEOS) and proper organosilanes using poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) amphiphilic block copolymer templates, P123 (EO₂₀PO₇₀EO₂₀) and F127 (EO₁₀₆PO₇₀EO₁₀₆). The modified SBA-15 and SBA-16 materials were synthesized by varying the molar ratio of organosilane to TEOS in the initial synthesis gel. The removal of polymeric templates, P123 and F127, was performed with ethanol/hydrochloric acid solution. In the case of SBA-15 the P123 template was fully extracted, whereas this extraction process was less efficient for the removal of F127 template from the SBA-16-type organosilicas; in the latter case a small residue of F127 was retained. The adsorption and structural properties of the resulting materials were studied by nitrogen adsorption-desorption isotherms at −196^∘C (surface area, pore size distribution, pore volumes), powder X-Ray diffraction, CHNS elemental analysis and high-resolution thermogravimetry. The structural ordering, the BET specific surface area, pore volume and pore size decreased for both channel-like and cage-like mesoporous organosilicas with increasing concentration of incorporated organic groups.