胶束催化

表面活性剂是由疏水基和亲水基组成的化合物,当表面活性剂在水中的浓度达到临界胶束浓度时,表面活性剂分子以几十个、几百个聚集在一起,形成疏水基向里,亲水基向外的胶束。缔合成胶束的表面活性剂分子数称为胶束聚集数,它通常随疏水基的疏水性的增强而增大。     

表面活性剂—工业的味精

凡能改变(通常为降低)液体表面张力的物质称为表面活性剂。表面活性剂分子一般总是由非极性的、亲油(疏水)的碳氢链部分即亲油基(憎水基)和极性的、亲水(疏油)的亲水基(憎油基)共同构成的;     

一种脂肽类生物表面活性剂的产生及特性研究

从油田采出水中分离到一株芽孢杆菌(Bacillus lichenifonnis)。菌种发酵液具有高表面活性,经分离提取获得浅黄色固体产物,其临界胶束浓度(cmc值)为30.0mg／L,该产物经聚丙烯酰胺凝胶电泳、红外光谱(IR)、色谱-质谱联用(GC-MS)和纸层析(PC)分析表明：其疏水基半分子为β-甲基十四碳脂肪酸及β-羟基十八碳脂肪酸;亲水基半分子含Asp、Glu、Ile、Val、Lys等氨基酸,为一种由脂肪酸和肽组成的脂肽类生物表面活性剂。特性分析表明：该表面活性剂可耐高温和高浓度盐,pH适应范围较广,对原油具有较强的乳化、增溶、脱附和降黏作用。     

用于人体保健用品的表面活性剂

所有表面活性剂都具有两性特性的分子构型,那就是它们的分子有一个亲水基与一个相平衡的疏水基。后者常由一个长链的碳氢化合物构成。表面活性剂的特有性质就是分子中的这种相反的两重性。例如,当表面活性剂溶于水时,其分子吸附于表面或界面,并按规则排列,结果是亲水基吸附于水相使疏水基远离液体表面,这样出现了一个聚集分子的吸附层。如果表     

双亲水基与单亲水基表面活性剂的物化性能之比较

通常，典型的用于清洗配方的表面活性剂分子一头只有一个亲水基，如单磺酸基等；另一头是具有脂肪碳链的疏水基。正是这些同时具亲水基和疏水基的物质，其溶液具备了特殊的化学性能(见图1)……     

易处理的外科手术防护罩和面罩用的防反射、防结露涂料组合物

题述组合物利用无机金属氧化物(例如二氧化硅),与带亲水基和疏水基的表面活性剂拼用。其中,亲水基选自吡咯烷酮和带有≥2个羟基(被≤5个原子隔开)的多羟基(羟基数≥表面活性剂分子中所带的疏水基总数);疏水基为C≥4烃链或C≥3全氟化游离基。用该组合物涂覆透明底材的至少一面后。表现为在润湿试验中的液滴直径≥4mm,所得底材对550nm光的透射率≥3％。该涂料组合物特别适用于制备易处理的外科手术防护罩和面罩。     

葡甘聚糖改性大豆蛋白作为药物乳化剂的研究

用天然大豆蛋白和葡甘聚糖,利用羟氨反应使蛋白质分子的侧链氨基与多糖分子的末端不饱和羰基反应生成稳定的共价键,进而形成以多羟基葡甘聚糖为亲水基,大豆蛋白为疏水基的新型两亲分子。结果表明,葡甘聚糖改性大豆蛋白是良好的药用乳化剂,制成的O/W乳状液稳定性明显优于Tween-60制成的乳状液。     

Gemini表面活性剂的吸附、自聚和性质

Gemini表面活性剂通常是由两 (或三 )条疏水链、两个亲水基和一个连接基组成的两性分(离 )子 ,与由单亲水基和单疏水基构成的单体表面活性剂分 (离 )子相比较 ,在临界胶团浓度、界面性质和溶解性等方面有着独特的性质。由于其电荷密度高 ,临界胶团浓度低 ,并且有很低的 Krafft点 ,能在低浓度下与高碳烷烃形成超低界面张力 ,在石油开发中有着很好的应用前景。详述了该类新型表活性剂的吸附、自聚、性质 ,比较了与单体表面活性剂的差别     

表面活性剂的化学结构与性能的关系

1.亲水亲油平衡值(HLB值)与性能之间的关系表面活性剂要呈现特有的界面活性,必须使疏水基和亲水基之间有一定的平衡。石蜡HLB值=0(无亲水基),聚乙二醇HLB值=20(完全     

表面活性剂乳化类型判定方法研究——体积平衡（VB）值法

介绍了一种判定表面活性剂乳化类型的新方法——体积平衡（VB）值法。VB值是表面活性剂的亲水基与亲油基体积比。亲油基体积是亲油基中碳、氢原子共价半径的球体体积之和。亲水基体积色两种情况：非离子型表面活性剂亲水基体积是亲水基中原子共价半径的球体体积;离子型表面活性剂亲水基体积是阳离子或阴离子形成的水合离子的体积与疏水基离子的亲水部分的体积之和。试验结果表明,VB值大于1即为水包油型表面活性剂,VB值小于1则为油包水型表面活性剂。VB值是判定表面活性乳化类型及溶解性等性质有有效方法之一。VB值具有加和性。     

The influence of hydrophilic and hydrophobic domains on water wettability of 2-hydroxyethyl methacrylate-styrene copolymers

Cooligomers and ABA-type block copolymers composed of a hydrophilic monomer, 2-hydroxyethyl methacrylate (HEMA), and a hydrophobic monomer, styrene, were synthesized to study the relation between their microstructure and hydrophilic and hydrophobic functions. Films of cooligomers and ABA-type block copolymers were cast from DMF solutions at 40°C. The wettability, which was determined from the contact angle with water, increased considerably when HEMA mole fraction reached around 0.8 in the cooligomer system and around 0.9 in the ABA-type block copolymer system. The microstructures of the copolymer films were observed by electron microscopy using the osmium tetroxide fixation technique. The morphologic change in the domain structure was observed at an HEMA mole fraction of about 0.8 in the cooligomer system and about 0.9 in the ABA-type block copolymer system. It is suggested that hydrophilic and hydrophobic functions are largely influenced by the state of aggregation of each segment, that is, the size and geometry of the hydrophilic and hydrophobic domains.     

Synthesis of novel amphiphilic pH‐sensitive polyurethane networks through water‐in‐oil soap‐free emulsion polymerization process. I. Microstructural differences and swelling behaviors

pH‐sensitive amphiphilic networks are synthesized from urethane acrylate anionomer (UAA) precursor chains. The microstructures of these networks are very sensitive to the nature of and the amount of solvent used during crosslinking. Whereas dioxane forms relatively homogenous solution, water preferentially interacts with hydrophilic segment of UAA chains, causing the microphase separation between hydrophilic moieties and hydrophobic main chains. This microphase separation was locked‐in by crosslinking reaction, enhancing largely the hydrophilicity of UAA networks and the hydrophobic aggregation. The UAA gels, prepared with water (UAAG) and/or dioxane (UADG), exhibit quite different swelling behaviors in the same dissolution medium because of their completely different microstructures. The improved hydrophilicity of UAAG gels due to the hydrophilic/hydrophobic microphase separation is confirmed by measuring the contact angle to water. These microphase‐separated hydrophilic domains on UAA gel matrix, which are observed by scanning electron microscopy measurement, influence the mechanical property of dried UAA gels as well. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 2115–2127, 2000     

Preparation and solution performance for the amphiphilic polymers with different hydrophobic groups

An amphiphilic polymer with twin‐tailed hydrophobic groups was prepared by micellar polymerization of acrylamide as hydrophilic monomers, 2‐acryloylamino‐2‐methyl‐1‐propanesulfonic acid as functional monomers and N,N‐dodecyl acrylamide as hydrophobic monomers. Using the same method, containing single‐tailed hydrophobic group of the amphiphilic polymer and not containing the hydrophobic group of ordinary polymer were prepared. The molecular structure of the product was characterized by infrared spectrum and ¹H nuclear magnetism resonance spectrum. By inclusion complexation of β‐cyclodextrin (β‐CD), the hydrophobic association on the apparent viscosity contribution rate was studied. Relationship between hydrophobic group structure and its performance was investigated by the rotational viscometer, scanning electron microscopy (SEM), fluorescence spectroscopy, and rheometer. The results showed that amphiphilic polymers containing twin‐tailed hydrophobic groups had a lower critical aggregation concentration (CAC). When the amphiphilic polymer concentration was higher than CAC, hydrophobic association was stronger, which led to a higher apparent viscosity contribution rate. At the same polymer solution concentration, amphiphilic polymer containing twin‐tailed hydrophobic group had better performance on temperature resistance, salt tolerance, and mechanical shear resistance compared with the other two polymers. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44744.     

改性海藻酸钠载药纳米胶囊对氯氟氰菊酯的释放

以DCC/DMAP偶联酯化反应将胆固醇基接枝到天然多糖海藻酸钠上,制备了胆固醇基接枝海藻酸钠衍生物(CSAD),采用乳化法对氯氟氰菊酯进行了负载,得到载药纳米胶囊。通过FTIR、1H NMR、荧光光谱、动态光散射、TEM和释药实验分别对改性海藻酸钠的结构和疏水性能以及载药纳米胶囊的形貌结构和释药性能进行了表征。结果表明改性海藻酸钠的取代度为5.3%~7.9%,其临界聚集浓度由1.23mg/L降为0.26~0.63mg/L,且随着取代度的增大,疏水基的增多,临界聚集浓度降至更低。所制备的载药纳米胶囊的d50为576.4?.4nm。Zeta电位值为-32.3?.6mV,在水溶液中能够表现出极好的稳定性能。对比常规微乳剂CSAD的氢键作用是其具备缓释性能的关键所在。     

Rheology and morphology of nanosilica‐containing polypropylene and polypropylene/liquid crystalline polymer blend

We studied the rheology and morphology of hydrophilic and hydrophobic silica containing polypropylene (PP) and PP/liquid crystalline polymer (LCP) blend. It was found that hydrophilic silica has higher tendency for aggregation and forms bigger aggregate size. The lower percolation threshold and the higher fractal dimension for hydrophilic silica are due to its stronger particle–particle interaction compared with the hydrophobic one. Although the hydrophobic silica has lower thickening capability and lower coalescence hindrance by aggregates, its presence at the interface of PP/LCP blend results in smaller droplet size and higher elasticity of hybrid samples in comparison to hydrophilic silica. These results confirm that the hydrophobic silica has a compatibilization capability for PP/LCP blend, whereas the hydrophilic silica mostly works as a thickening agent and suppresses the coalescence. We suggested that for comparison of different particulate compatibilizers, the elasticity of filled blend sample against filled matrix phase can be used in high and low frequency ranges. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Dissolution of cholesterol gallstones by bile acids in the prairie dog

The effect of chenodeoxycholic acid, ursodeoxycholic acid and hyodeoxycholic acid on gallstone dissolution was studied in the prairie dog. Cholesterol gallstones were found in all animals after feeding a semipurified diet plus 1.2% cholesterol for six wk. Gallstone regression was examined by feeding a chow diet containing the bile acids (chenodeoxycholic acid, ursodeoxycholic acid or hyodeoxycholic acid) alone (30 mg/kg/day) or in combination (chenodeoxycholic acid plus ursodeoxycholic acid) for an additional six wk. Chenodeoxycholic acid was effective in dissolving established cholesterol gallstones (two out of 16 animals still had stones) and cholesterol crystals (six out of 16 animals had crystals); the hydrophilic bile acids, ursodeoxycholic acid and hyodeoxycholic acid, were ineffective in the six-wk regression study. The lithogenic indices averaged 1.09 at the end of the induction period: all biles became unsaturated with respect to cholesterol after the six-wk regression period (group 1, 0.82; group 2, 0.66; group 3, 0.81; group 4,0.84; group 5, 0.66). Cholesterol levels in liver, plasma and bile were elevated after the six-wk induction phase (4.59 mg/g, 610 mg/dl and 0.36 mg/ml, respectively) but returned to near normal levels after the six-wk regression period. Biliary bile acids contained increased levels of the dietary bile acid administered to each group. This experiment shows that relatively hydrophobic bile acids may be more effective than hydrophilic bile acids for gallstone dissolution during the period studied.     

Fabrication of super-hydrophobic film from PMMA with intrinsic water contact angle below 90°

Super-hydrophobic film is commonly prepared from hydrophobic materials. Poly(methyl methacrylate) (PMMA) is considered as a hydrophilic polymer (intrinsic contact angle below 90°) with the water contact angle (CA) of 68°. However, a super-hydrophobic PMMA film with CA of 154° was obtained by treating polystyrene (PS) and PMMA blended film in a warm selective solvent, cyclohexane. The surface was characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and infrared spectroscopy (FT-IR). The results show that the conversion from the hydrophilic surface to a super-hydrophobic one is due to the cooperation of the micro-, nano-structure and the side group reorientation in the PMMA chains at the topmost.     

Method for the preparation of hydrophilic/hydrophobic patterned surfaces with photoinitiated hydrosilylation

Recently, there has been considerable interest in hydrophilic/hydrophobic patterned surfaces because they serve as important templates for the selective deposition of various materials. We report a novel and simple method for the creation of hydrophilic/hydrophobic patterned surfaces using soft UV irradiation (365‐nm wavelength). The method employs a photoinitiated hydrosilylation reaction of vinyl‐terminated polydimethylsiloxane with H? Si groups catalyzed by platinum(II) acetylacetonate. In UV‐irradiated regions, the photohydrosilylation reaction occurs, forming hydrophobic regions. In unirradiated regions, the remaining H? Si groups are converted into HO? Si groups in the presence of aqueous sodium hydroxide to form hydrophilic regions. The photoinitiated hydrosilylation reaction is completed within a little over 1 min, and this has been confirmed by reflection–absorption spectroscopy. The value of the water contact angle for the hydrophilic regions is about 10°, and that for the hydrophobic regions is about 103°. The success of pattern formation at the micrometer scale has been confirmed by scanning electron microscopy. The difference in the chemical structure at the surface has been confirmed by the decoration of the hydrophilic regions by a fluorescent dye and characterization with a fluorescence analyzer. Atomic force microscopy has shown that the height of the hydrophobic regions is about 20 nm. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

pH‐Responsive PEGylated nanoparticles based on amphiphilic polyaspartamide: preparation,physicochemical characterization and in vitro evaluation

A series of amphiphilic graft copolymers based on polyaspartamide were synthesized by successive aminolysis reactions of polysuccinimide using 2‐diisopropylaminoethyl (DIP), O‐(2‐aminoethyl)‐O′‐methylpolyethylene glycol (PEG) and lauryl amine as pH‐sensitive, hydrophilic and hydrophobic groups, respectively. The pH‐dependent self‐assembly behavior of the aqueous copolymer solution was investigated. Nano‐aggregation, which was induced by a hydrophilic/hydrophobic shift of the DIP group in solution, occurred at a pH in the vicinity of the pK_a of the DIP group. The mean diameter of the nano‐aggregate could be modulated by changing the compositions of both pendants. The mean diameter of the nanoparticles increased with increasing solution pH from 6.5 to 8. The dissolution of paclitaxel into these amphiphilic nanoparticles was attempted and the pH‐dependent release behavior was examined using a solvent‐casting method. The results showed a significantly faster release of paclitaxel at pH = 6.5, which is a tumoral acidic pH, than at neutral physiological pH. These pH‐sensitive PEGylated polyaspartamide derivatives have potential use as a tumor‐targeting delivery system.     

Thermotropic behavior of stratum corneum lipids containing a pseudo-ceramide

The mechanism of the self-assembly of the lamellar structure of natural stratum corneum lipids (SCL) has been a subject of considerable interest. We have examined this question by using a synthetic pseudo-ceramide (sphingolipid E, SLE) which was analogous to the naturally occurring ceramide type 2. The thermotropic properties and the structural characteristics of SLE, together with other main components of SCL, fatty acids, and cholesterol, were investigated by differential scanning calorimetry and X-ray analysis. A mixture of SLE and stearic acid was in a stable α-form having a lamellar structure, which is very similar to that of natural SCL. However, lipid mixtures in which stearic acid were replaced by oleic acid did not form lamellar structures, and existed in the crystalline states. This indicates that the stable bilayer formation of the natural SCL is strongly dependent on the molecular fatty acid structure. Moreover, incorporation of cholesterol (0–50%) into equimolar mixtures of SLE/stearic acid and of SLE/oleic acid caused a marked decrease of melting entropies, while the aggregation states of both systems were not changed. This effect of cholesterol can be attributed to the disorder of the molecular packing. These results suggest that the hydrophobic interactions between the SCL are important for bilayer formation as are the hydrophilic interactions between the polar groups.