梳状结构硅表面活性剂的溶液性质

采用氢硅化法制备得到了一系列具有梳状结构的非离子有机硅表面活性剂(PESO)。利用红外光谱和核磁共振氢谱对产物的结构进行了表征,分析了疏水基团的含量对PESO表面活性剂表面张力和临界胶束浓度的影响,研究了PESO表面活性剂在水溶液表面的吸附现象及在水溶液中的聚集行为,探讨了其在水溶液中形成的胶束的尺寸和分布。研究表明,随着疏水组分含氢硅油(PHMS)含量的增加,PESO表面活性剂分子越易缔合形成胶束且胶束的平均粒径增大。当PHMS含量由25%增加至67%时,临界胶束浓度(CMC)由0.828 g/L降至0.613 g/L,γCMC可降至22.11 mN/m,表面吸附量(Γ)可达3.31μmol/m2,每个表面活性剂分子吸附在空气/水界面的平均面积(A)仅为0.502 nm2,PESO表现出较好的表面活性。此外,荧光光谱法研究PESO聚合物在水溶液中的聚集行为发现,随着表面活性剂浓度的增加,第一、第三发射峰的荧光强度比值(I1/I3)不断减小,达到PESO的临界缔合浓度后,芘分子增溶于PESO胶束中,I1/I3趋于恒定。     

负压膜蒸馏中不同类型表面活性剂的润湿机理研究

表面活性剂导致的膜润湿是膜蒸馏技术在处理实际废水面临的主要问题.为了缓解膜润湿现象,采用新型的负压膜蒸馏来评价不同类型表面活性剂盐溶液的润湿能力,并利用扫描电子显微镜、动态光散射等手段分析了表面活性剂的润湿和污染机理.首先,恒浓处理0.1 mmol/L SDS、CTAB以及Tween-20盐溶液,当料液含阴离子表面活性剂(SDS)时,膜通量稳定,冷凝液电导率保持在3μS/cm以内.而料液含阳离子(CTAB)和非离子表面活性剂(Tween-20)时,膜通量都衰减,甚至出现负值.通过分析污染膜表面以及溶液中表面活性剂胶束的粒径,证实CTAB和Tween-20是通过胶束污染膜表面,造成膜润湿.为了探究胶束污染和表面活性剂浓度之间的关系,分别测试表面活性剂浓度为0.1CMC、0.5CMC、1.0CMC的盐溶液,其中SDS、CTAB以及Tween-20的临界胶束浓度(CMC)分别为9.6×10^-3 mol/L、9.1×10^-5 mol/L和6×10^-5 mol/L.当分别处理9.1×10^-6 mol/LCTA...     

20碳钢水基清洗剂的配制及应用效果

为了洗净量大面广的钢铁制品表面的防锈油,配制了一种有效的20碳钢水基清洗剂。采用单因素试验法,逐一对5种市售非离子表面活性剂进行了除油清洗,优选出表面活性剂(脂肪醇聚氧乙烯醚)后,确定PAA分散剂、助剂和缓蚀剂的最佳含量。按照国标分别采用DDS-307A电导仪、722N可见分光光度计测定清洗剂的临界胶束浓度和浊点。结果表明:20碳钢水基清洗剂的最佳组成为4 g/L 087型表面活性剂,3 g/L 731分散剂,12 g/L无水碳酸钠,4 g/L硅酸钠,1~2 g/L十二烷基硫酸钠。本清洗剂碱度小、耐酸性好、除油效果能满足生产需要。     

聚己内酯/聚乙二醇/聚丙交酯两亲性共聚物纳米胶束的制备与表征

合成了两亲性聚己内酯-乙二醇-丙交酯(PCELA)三嵌段共聚物,采用沉淀法制备了粒径范围在40～120nm的PCELA纳米胶束.以芘为探针,利用荧光探针技术、动态光散射(DLS)、透射电镜(TEM)研究了PCELA在水中的行为.结果表明,临界胶束浓度(CMC)随着PCL-PLA/PEO的比率增大而增大,胶束粒径受到PCL-PLA/PEO比率和PCELA共聚物分子量的影响,胶束为具有核/壳结构的规则纳米球体.     

分子内电荷转移荧光探针法测定表面活性剂的临界胶束浓度

研究了分子内电荷转移荧光体4-二甲氨基查尔酮(DMAC)在表面活性剂水溶液中的荧光光谱。观察到随表面活性剂浓度增大,DMAC 的荧光光谱先红移然后蓝移,而荧光强度呈“S”型变化并于光谱位移方向转折处突跃。突跃处对应的表面活性剂浓度即为其临界胶束浓度(cmc)。结果表明由该法测定的 cmc 与已报道值符合,说明方法的可行性与准确性。用该法测定表面活性剂/β-环糊精混合体系的 cmc,表明β-环糊精的存在诱导了胶束的形成。     

非离子表面活性剂BS—FJ在硼酸溶液中胶束化热力学性质研究

本文用滴体积法测定了对硼酸结晶有显著影响的非离子表面活性剂在硼酸溶液中不同温度条件下的表面张力，求得了对应的临界胶束浓度。根据质量作用定律，推出了表面活性剂胶束化时的热力学模型并对其热力学性质进行了计算和讨论。     

两亲性PS-b-PEG-b-PS三嵌段共聚物的合成及在水中的聚集行为研究

采用原子转移自由基(ATRP)合成了一系列两端为短的聚苯乙烯(PS)嵌段,中间为长的聚乙二醇(PEG)嵌段的PS-b-PEG-b-PS两亲性三嵌段共聚物。采用1H-NMR、荧光探针法和动态光散射研究了PS和PEG嵌段长度对三嵌段共聚物在水中聚集行为的影响。结果表明:三嵌段共聚物在水中可以形成以PS嵌段为核和以PEG嵌段为壳的球形胶束,其胶束化的临界胶束浓度(CMC)随着PS嵌段长度增加而减小,流体力学半径(Rh)随PEG嵌段长度增长而增大,调整PS嵌段长度能有效地调控胶束的形成。胶束对疏水分子芘具有很好的装载能力,芘在胶束中的分配平衡常数(Kv)为105,随PS嵌段长度增加而增大。     

直链淀粉-鹅去氧胆酸接枝聚合物的合成及其自组装行为

使用1-乙基-3-(3－二甲基氨丙基)-碳化二亚胺(EDC)/N-羟基琥珀酰亚胺(NHS)交联剂合成一种直链淀粉接枝鹅去氧胆酸聚合物(Amylose–chenodeoxycholic acid conjugates, AMY-CDCA),并用傅里叶变换红外光谱(FTIR)、核磁共振氢谱(¹H NMR)和紫外光谱法对其进行了表征。结果表明,CDCA已经成功地接枝到直链淀粉骨架上,接枝度为138.15/100个葡萄糖单元。可用透析法将AMY-CDCA聚合物制备成球形并具有核壳结构的胶束,其平均粒径为224 nm,多分散指数为0.110。使用疏水性荧光探针芘和尼罗红研究了胶束的组装行为。结果表明,聚合物的临界胶束浓度(CMC)为2.8×10^-3 mg/mL,其疏水核心对尼罗红有增溶作用。     

荧光探针法研究PMMA-g-PEG的胶束化行为

由聚乙二醇大分子单体(MA-PEG)与甲基丙烯酸甲酯(MMA)在二甲基甲酰胺(DMF)中进行共聚反应,生成了以PEG为支链,PMMA为主链的接枝共聚物(PMMA-g-PEG)。增加MA-PEG大分子单体的用量,可使PMMA-g-PEG的数均分子量略为增大,分子量分布保持在1.7左右。核磁共振测定表明PMMA-g-PEG的结构明确。进而以芘(Py)为荧光探针,测定了PMMA-g-PEG的临界胶束浓度(CMC),并跟踪了Py从H2O/DMF混合介质中向胶束的增容过程。表明PMMA-g-PEG的CMC较低时,介质中的水含量对Py的增容有较大的影响。透射电子显微镜观察发现,由PMMA-g-PEG自组装形成的聚合物胶束形态为球形,粒径在180nm左右,在水中具有稳定的形态结构。     

叶酸受体靶向的聚乳酸共聚物胶束的制备及性质研究

叶酸偶联的羟脯氨酸-乳酸共聚物(PLLA-PHpr-FA)是一种新型的叶酸受体靶向生物降解聚合物,研究PLLA-PHpr-FA自组装形成胶束的能力及胶束的性质。临界胶束浓度(CMC)用芘荧光探针测定,结果表明,CMC很低并依赖于乳酸/羟脯氨酸的比例。透射电子显微镜(TEM)显示共聚物胶束呈现典型的核/壳结构。动态激光光散射(DLS)测定粒径及粒径分布结果显示,粒径受乳酸/羟脯氨酸比例和丙酮量调控,但粒子几乎不受稀释的影响。用紫外分光光度法测定胶束的载药量和包封率表明,共聚物胶束对疏水性药物的包载较好。因此,PLLA-PHpr-FA胶束可以作为肿瘤靶向的药物载体。     

Aggregation behavior of betaine-amphiphiles in the presence of polyvinylpyrrolidone

The aggregation behavior of zwitterionic surfactant dodecylbetaine (C₁₂BE) with and without polyvinylpyrrolidone (PVP) has been investigated by means of surface tension and steady-state fluorescence techniques. It shows that addition of PVP results in a decrease in the aggregation number of C₁₂BE micelle and “hydrophobic index” (I₁/I₃) of the probe (pyrene and pyrene-1-carboxaldehyde). PVP molecules are responsible for the phenomena: they bind to the surface of the micelle and prevent the rapid exchange of amphiphiles between micelles and water phase. There are two transition points in the plot of surface tension vs. concentration of C₁₂BE in the presence of PVP. The results indicate that the association takes place between PVP and C₁₂BE when the C₁₂BE concentration is above a critical aggregation concentration (CAC).     

Photophysical Characterization of Insulin Denaturation and Aggregation at Hydrophobic Interfaces

The peak III/I ratio of pyrene monomer fluorescence was used to characterize surface-induced insulin denaturation and aggregation. An indicator of the hydrophobicity of pyrene's microenvironment, the IIM ratio can be used to study self-association of amphipathic molecules. In sodium lauryl sulfate (NaLS), the III/I ratio was 0.71 below the critical micelle concentration (CMC) and increased to 0.98 when the concentration was above the CMC. When insulin was placed in a polystyrene cuvet for 2 days at 37°C, the IWI ratio decreased from 0.84 to 0.78. The decrease in III/I ratio corresponds to surface-induced denaturation of insulin which exposed pyrene to a more polar environment. Increasing the duration of incubation for up to 12 days increased the III/I ratio to 1.06. Increased hydrophobicity of pyrene's environment correlates with the self-association of insulin. Once the aggregates reached a critical size, they began precipitating as was evident by an increase in the turbidity (absorbance at 600 nm) of solution. The results of this study support previous hypothesis that the aggregation and precipitation of insulin at hydrophobic interfaces is initiated by adsorption and surface-induced denaturation.     

Photophysical Characterization of Insulin Denaturation and Aggregation at Hydrophobic Interfaces

Abstract

The peak III/I ratio of pyrene monomer fluorescence was used to characterize surface-induced insulin denaturation and aggregation. An indicator of the hydrophobicity of pyrene's microenvironment, the IIM ratio can be used to study self-association of amphipathic molecules. In sodium lauryl sulfate (NaLS), the III/I ratio was 0.71 below the critical micelle concentration (CMC) and increased to 0.98 when the concentration was above the CMC. When insulin was placed in a polystyrene cuvet for 2 days at 37°C, the IWI ratio decreased from 0.84 to 0.78. The decrease in III/I ratio corresponds to surface-induced denaturation of insulin which exposed pyrene to a more polar environment. Increasing the duration of incubation for up to 12 days increased the III/I ratio to 1.06. Increased hydrophobicity of pyrene's environment correlates with the self-association of insulin. Once the aggregates reached a critical size, they began precipitating as was evident by an increase in the turbidity (absorbance at 600 nm) of solution. The results of this study support previous hypothesis that the aggregation and precipitation of insulin at hydrophobic interfaces is initiated by adsorption and surface-induced denaturation.     

新型不对称双季铵盐表面活性剂的制备及缓蚀性能

本文以十二烷基二甲基叔胺、十六烷基二甲基叔胺、氯乙酰氯和1,3-丙二胺为原料,通过三步法制得一种新型高效、环境友好的不对称双季铵盐表面活性剂,研究了其在1 mol/L盐酸溶液中对2024 Al-Cu-Mg合金表面的缓蚀性能和机理.通过红外光谱和核磁共振氢谱对其结构进行表征;通过表面张力获得其临界胶束浓度(CMC);利用...     

Characterization of the physicochemical properties of the micelles of platelet-activating factor (C18:0)

The purpose of this study was to clarify the physicochemical properties of the micelles of platelet-activating factor (PAF; C_18:0). The critical micelle concentration (CMC) of PAF (C_18:0) was determined (0.20 μM) using fluorescence techniques. The fluidity and the micropolarity of the PAF (C_18:0) micelle were similar to those of the micelle of stearoyl lysophosphatidylcholine.     

Self-association behaviour of protein:surfactant systems in alcohol/water mixtures

The effect of the addition of short-chain monohydric alcohols (ethanol and propan-2-ol) to the protein:surfactant system lysozyme:sodium dodecyl sulfate (Lz:SDS) in aqueous solution was investigated using a conductometric technique. A second protein:surfactant system, bovine serum albumin:SDS (BSA:SDS) was also investigated so that the effect of a different protein conformation and composition could be compared. The critical aggregation concentration (CAC) of the protein forming the complex and the critical micelle concentration (CMC *) of SDS in the presence of protein, at different alcohol concentrations, were determined. It was found in both cases that the addition of alcohol does not produce a significant change in the CAC, whereas the CMC * displays variation with alcohol concentration that shows an inversion in the ranges 0.05-0.06 ethanol mole fraction and 0.02-0.03 propan-2-ol mole fraction. This suggests that, in contrast with the CAC behaviour, the major factor that drives SDS micellization in the presence of protein is the variation in water structure. Results also suggest that it occurs in the same way for both proteins, where electrostatic interactions are the main force in the formation of the complex. Conversely, hydrophobic interactions play the dominant role at the micellization stage, and only the extent of the interaction between protein:surfactant aggregates and surfactant species seems to depend on protein nature.     

A new type of anionic surfactant with four carboxylates for the preparation of mesoporous materials

In this paper, a new type of anionic surfactant containing four carboxylates was synthesized by a four-step synthetic reaction including bromination reaction and primary amide protective reaction. Intermediates and final products of each step in the whole synthetic process were characterized by ¹H NMR and MS. Purification of the anionic surfactant was accomplished through combination of recrystallization and silica gel column chromatography. The structure and the critical micelle concentration (CMC) of this surfactant at different temperatures were also investigated. Unlike traditional mono-carboxylate surfactant easy to form lamellar mesostructure, this surfactant has the hexagonal mesophase structure and comparatively low CMC, hopefully to be applied in the preparation of mesoporous metal oxides.     

二元阳离子表面活性剂的CMC及相互作用

采用紫外法和荧光法测定了二元阳离子混合表面活性剂体系(十六烷基三甲基溴化铵和十二烷基三甲基溴化铵、十六烷基三甲基溴化铵和十四烷基三甲基溴化铵)的临界胶束浓度(CMC)。在正规溶液理论的基础上计算出形成胶束时的相互作用参数βm、超额自由能ΔGex和胶束组成xi,分析结果表明,两种二元体系的CMC值介于纯组分之间,胶束中的组成都与理想混合有一定偏差;胶束相中两组分间的作用力为吸引力;当胶束相中CTAB的摩尔分数增大时,吸引力增强。