硅氧烷乳液聚合过程中大颗粒形成机理研究Ⅰ．阳离子型乳液的耐电解质稳定性

探讨了二甲基聚硅氧烷阳离子型乳液耐电解质稳定性的影响因素。结果表明,加入少量的非离子型表面活性剂与阳离子型乳化剂并用进行乳液聚合,可以保护乳液粒子,防止由于电解质引起的乳液粒子的相互凝聚而形成大颗粒。     

硅氧烷乳液聚合过程中大颗粒形成机理研究：Ⅰ.阳离子型乳液的耐电解质…

探讨了二甲基聚硅氧烷阳离子型乳液耐电解质稳定性的影响因素。结果表明，加入少量的非离子型表面活性剂与阳离子型乳化剂并用进行乳液聚合，可以保护乳液粒子，防止由于电解质引的乳液粒子的相互凝聚而形成大颗粒。     

二甲基聚硅氧烷阴离子型乳液的稳定性

作为织物柔软剂,二甲基聚硅氧烷阴离子型稀乳液的耐电解质稳定性对实际应用有着重要的意义。然而有关这方面的报道极少,而关于非离子型和阴离子型表面活性剂对它的电解质凝聚稳定性的影响至今未见报道。     

混合阴阳离子表面活性剂体系的物理化学性质

测定并比较了TX-100(C_8ΦE_(9.8))及TX-100的硫酸盐(_8CΦE_(9.8)S)分别与阳离子表面活性剂(C_nPy, n=10, 12, 14; C_mNM_3, m=16, 18)混合后, 混合表面活性剂的表面活性、水溶液的稳定性、起泡能力和泡沫稳定性等物理化学性质。     

微乳液法制备YF3:Er纳米材料

微乳液[1～2]通常是由表面活性剂、助表面活性剂(通常为醇类)、油(通常为碳氢化合物)和水(或电解质水溶液)组成的透明的、各向同性的热力学稳定体系.微乳液中,微小的水池被表面活性剂所组成的单分子层界面所包围而形成微乳颗粒,其大小可控制在几至几十纳米之间.微小的"水池"尺度小且彼此分离,因而构不成水相,通常称为"微反应器".本文采用了CTAB、正丁醇、正辛烷和水等组成的微乳液体系[3].     

非离子型表面活性剂组成的微乳液热力学性质 (IV) 烷烃的碳原子数影响

由表面活性剂、醇、油和水所组成的微乳液,油相的烷烃长度会影响到微乳液的性质,主要表现在界面相组成和界面张力.Birdi 用加溶法研究以十六烷、硬脂酸钠、水和醇(从C_5到C_9)所组成的微乳液,醇的碳原子数n_a 与标准自由能△G(?)有以下关系:△G(?),醇=1563-839.5n_a(J·mol~(-1)在同样体系内,戊醇和不同烷烃则:     

pH和光对复合型乳液拓扑结构的调控（英文）

本文采取温度诱导相分离法制备了正庚烷-全氟己烷-水(H/F/W)三相复合型乳液,并利用pH和光双重刺激响应型表面活性剂1-[2-(4-癸基偶氮苯-苯氧基)-乙基]-1-二乙烯三胺(C_(10)AZOC_2N_3)成功实现了对该H/F/W复合型乳液形貌的调控。一方面,随着C_(10)AZOC_2N_3浓度的增加,H/F/W复合型乳液实现了从H/F/W型双重乳液经Janus乳液到F/H/W型双重乳液的相反转过程。另一方面,基于pH或紫外/蓝光激发有效调控了H/F/W复合型乳液在Janus乳液和F/H/W型双重乳液之间的可逆转换。调控机理可以解释为:pH改变或紫外/蓝光光照引起C_(10)AZOC_2N_3构型转变,降低了正庚烷/水界面张力,从而调控H/F/W复合型乳液形貌。本工作为双重环境刺激调控复合型乳液形貌提供了一个简便的新方法—仅仅通过引入一个双重刺激响应型表面活性剂。     

醇醚糖苷与纳米膨润土颗粒稳定乳状液的协同作用

以表面活性剂醇醚糖苷(AEG)和纳米膨润土颗粒(NPT-2)为乳化剂,制备了油酸甲酯乳状液,考察了AEG与NPT-2的配比对乳液体系稳定性和乳液粒径的影响,并通过表面张力和zeta电位测量对二者复配稳定乳液的机理进行了讨论。结果表明,单一使用表面活性剂AEG或者纳米膨润土颗粒NPT-2均不能得到稳定的油酸甲酯乳状液,将二者复配则乳液的稳定性有显著提高。固定AEG量逐渐增加NPT-2乳液粒径先增大后又减小,固定NPT-2量逐渐增加AEG,乳液体系粒径逐渐变小;AEG与NPT-2复配前后体系的表面张力曲线"滞后"现象及zeta电位的升高表明,AEG分子在纳米颗粒NPT-2上发生了吸附,协同稳定乳状液。     

电解质对非离子型微乳液的影响

本文通过测定微乳液的电导率和相图,研究了电解质(硝酸镍)对非离子型微乳液Triton X-100/正己醇/环己烷/水或硝酸镍水溶液系统稳定性的影响.发现分散相为水的微乳液体系中,表面活性剂的含量越大微乳液的电导率越大;分散相为盐溶液的微乳液体系中,微乳液的电导率随着盐溶液浓度的增大而减小;而且盐溶液浓度越大微乳液的含水量越小.     

阳离子Gemini表面活性剂12-3-12与DNA在模拟体液中的相互作用研究

采用紫外透射光谱、透射电镜、原子力显微镜、圆二色谱(CD)等方法探讨了阳离子Gemini表面活性剂C12H25N+(CH3)2-(CH2)3-(CH3)2N+C12H25·2Br-(12-3-12)与DNA在模拟体液(SBF)中的相互作用。结果表明,SBF中较高反离子浓度不但屏蔽了DNA和12-3-12之间的静电吸引作用,而且促进了12-3-12聚集体的产生和生长,导致低盐条件下体系中出现的沉淀溶解现象的消失。SBF中DNA与12-3-12之间存在强烈的相互作用;随着12-3-12的加入,表面活性剂分子在DNA链周围聚集,类网络结构的DNA逐渐变为类似于串珠的复合物,随后出现尺寸较大的类球形复合物以及较大复合物与较小表面活性剂聚集体共存的现象。CD谱结果显示,SBF中12-3-12可以诱导DNA的构象发生改变,由自然的B构型变成高度致密的ψ相。分子动力学模拟的离子液体中表面活性剂与带相反电荷聚电解质的相互作用过程及模式与实验结果吻合良好。模拟结果也表明,SBF中较高的反离子浓度提高了聚电解质的可压缩程度,导致相同条件下SBF中聚电解质的均方回旋半径远小于稀盐水溶液(10mmol/L Na Br)体系中的聚电解质均方回旋半径。较强的离子强度不但导致体系中聚电解质和带相反电荷表面活性剂之间的相互作用存在"假饱和"现象,而且也造成体系中表面活性剂在聚电解质周围聚集数显著提高。     

C_（12）C_6C_（12）Br_2/C_（12）E_（10）混合表面活性剂与DNA之间的相互作用

本文以构建有效的非病毒基因载体为目的,研究了C12C6C12Br2/C12E10混合表面活性剂组成对其与DNA之间相互作用的影响,并对混合表面活性剂与DNA形成的聚集体结构和形貌进行了表征。结果表明,当固定混合表面活性剂的总浓度为1.0 mmol/L时,混合表面活性剂组成的改变会引起混合体系浊度、聚集体表面电荷和聚集体...     

IR STUDIES OF THE THERMAL DECOMPOSITION OF[Rh_6(CO)_(16) Co_4(CO)_(12)]/SiO_2: EVIDENCE FOR THE FORMATION OF RhCo_3(CO)_(12)/SiO_2

IntroductionThepreparativeapproachofaneffectivebilTldslliccatalystisalwaysasubjectofboortantsignificanceinheterogeneouscatalysis.InourrecentstUdies,wefoundthatthebAnetallitcarbonylclustercoCo3(CO)12favorablygivesthebAnetalliccoCo3clusterontheSiOZsubdueaft…     

Adsorption and mobility of a lipase at a hydrophobic surface in the presence of surfactants

With the aim of being able to manipulate the processes involved in interfacial catalysis, we have studied the effects of a mixture of nonionic/anionic surfactants, C12E6/LAS (1:2 mol %), on the adsorption and surface mobility of a lipase obtained from Thermomyces lanuginosus (TLL). Surface plasmon resonance (SPR) and ellipsometry were used to analyze the competitive adsorption process between surfactants and TLL onto hydrophobic model surfaces intended to mimic an oily substrate for the lipase. We obtained the surface diffusion coefficient of a fluorescently labeled TLL variant on silica silanized with octadecyltrichlorosilane (OTS) by fluorescence recovery after photobleaching (FRAP) on a confocal laser scanning microscope. By means of ellipsometry we calibrated the fluorescence intensity with the surface density of the lipase. The TLL diffusion was measured at different surface densities of the enzyme and at two time intervals after coadsorption with different concentrations of C12E6/LAS. The surfactant concentrations were chosen to represent concentrations below the critical micelle concentration (CMC), in the CMC region, and above the CMC. The apparent TLL surface diffusion was extrapolated to infinite surface dilution, D0. We found that the presence of surfactants strongly modulated the surface mobility of TLL: with D(0) = 0.8 x 10(-11) cm2/s without surfactants and D0 = 13.1 x 10(-11) cm2/s with surfactants above the CMC. The increase in lipase mobility on passing the CMC was also accompanied by a 2-fold increase in the mobile fraction of TLL. SPR analysis revealed that surface bound TLL was displaced by C12E6/LAS in a concentration-dependent manner, suggesting that the observed increase in surface mobility imparts bulk-mediated diffusion and so-called rebinding of TLL to the surface. Our combined results on lipase/surfactant competitive adsorption and lipase surface mobility show how surfactants may play an important role in regulating interfacial catalysis from physiological digestion to technical applications such as detergency.     

Synchronous One-Pot (SOP) synthesis of hybrid structures: metal nanoparticles in self-assemblies of amphiphilic calix[6]biscrowns

Carbohydrate- and oligoethylene oxide-based surfactants behave quite differently despite the fact that they are both classes of nonionic surfactants. Intensive studies of a mixture at fixed molar ratio (1:1) of two very common sugar- and oligoethylene oxide-based surfactants, namely n-dodecyl-β-D-maltoside (β-C(12)G(2)) and n-dodecyl hexaethylene oxide (C(12)E(6)), revealed that most properties of the mixture are similar to those of the oligoethylene oxide-based surfactant. In the present work, this mixture is compared to respective "hybrid surfactants". Such hybrid surfactants are surfactants whose head group contains chemically linked carbohydrate and oligoethylene oxide units. In order to study the behaviour of this sort of compounds, we synthesised a new class of surfactants whose head group consists of one carbohydrate-like unit (myo-inositol) and three ethylene oxide units. New regiochemically defined ethoxylated inositol derivatives (referred to as C(12)I(1)E(3) and C(12)E(3)I(1) in the following) were synthesised and studied for their thermotropic and lyotropic liquid crystalline properties as well as for their surface activities. The results are compared with those of the reference systems β-C(12)G(2) and C(12)E(6), and their 1:1 mixture, respectively, and are discussed in terms of structure-property relations.     

Adsorption and micellar properties of a mixed system of nonionic-nonionic surfactants

We study the surface adsorption and bulk micellization of a mixed system of two nonionic surfactants, namely, ethylene glycol mono-n-dodecyl ether (C12E1) and tetraethylene glycol mono-n-tetradecyl ether (C14E4), at different mixing ratios at 15 degrees C. The pure C14E4 monolayer cannot show any indicative features of phase transition because of both hydration-induced and dipolar repulsive interactions between the bulky head groups. On the other hand, the monolayers of pure C12E1 and its mixture with C14E4 undergo a first-order phase transition, showing a variety of surface patterns in the coexistence region between the liquid expanded (LE) and liquid condensed (LC) phases under the same experimental conditions. For pure C12E1, the domains are of a fingering pattern while those for the C12E1/C14E4 mixed system are found to be compact circular and small irregular structures at 2:1 and 1:1 molar ratios, respectively. The critical micelle concentration (cmc) values of both the pure and the mixed systems were measured to understand the micellar behavior of the surfactants in the mixture. The cmc values of the mixed system were also calculated assuming ideal behavior of the surfactants in the mixture. The experimental and calculated values are found to be very close to each other, suggesting an almost ideal nature of mixing. The interaction parameters for mixed monolayer and micelle formation were calculated to understand the mutual behavior of the surfactants in the mixture. It is observed that the interaction parameters for mixed monolayer formation are more negative than those of micelle formation, indicating a stronger interaction between the surfactants during monolayer formation. It is concluded that since both the surfactants bear EO units in their head groups, structural parity and hydrogen bonding between the surfactants allow them to be closely packed during monolayer and micelle formation.     

Untersuchung von synthetischen mit nichtionogenen oberflächenaktiven Stoffen stabilisierten Latices

Zusammenfassung Es sind Polychloropren- und Butadienstyrollatices synthetisiert worden, die durch nichtionogene oberflächenaktive Stoffe vom Typ OP mit verschiedenem Oxyäthylierungsgrad sowie von OS-20 stabilisiert wurden. Es sind die Besonderheiten der kolloidchemischen Eigenschaften dieser Latices aufgeklärt und der Prozeß von deren Koagulation bei der Einwirkung von Elektrolyten und Erhöhung der Temperatur untersucht worden.

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Summary Polychloroprene and butadiene-styrene latices, stabilized by nonionic surfactants OP type with various degrees of polyoxyethylation and OS-20 as well have been synthesized. One found out special characteristics of colloidal-chemical properties of these latices and it has been studied the process of their coagulation under the action of electrolytes and on raising the temperature.

     

Adsorption of alkyl polyglucosides on the solid/water interface: equilibrium effects of alkyl chain length and head group polymerization

The equilibrium adsorption behavior of two n-alkyl-beta-D-glucosides (octyl (C8G1) and decyl (C10G1)) and four n-alkyl-beta-D-maltosides (octyl (C8G2), decyl (C10G2), dodecyl (C12G2), and tetradecyl (C14G2)) from aqueous solution on a titania surface, as measured by ellipsometry, has been investigated. The main focus has been on the effect of changes in the alkyl chain length and headgroup polymerization, but a comparison with their adsorption on the silica/water and air/water interfaces is also presented. Some comparison with the corresponding adsorption of ethylene oxide surfactants, in particular C10E6 and C12E6, is given as well. For all alkyl polyglucosides, the maximum adsorbed amount on titania is reached slightly below the critical micelle concentration (cmc), where it levels off to a plateau and the amount adsorbed corresponds roughly to a bilayer. However, there is no evidence that this is the actual conformation of the surfactant assemblies on the surface, but the surfactants could also be arranged in a micellar network. On hydrophilic silica, the adsorbed amount is a magnitude lower than on titania, corresponding roughly to a layer of surfactants lying flat on the surface. A change in the alkyl chain length does not result in any change in the plateau molar adsorbed amount at equilibrium; however, the isotherm slope for the alkyl maltosides increases with increasing chain length. Headgroup polymerization on the other hand affects the adsorbed amount. The alkyl glucosides start adsorbing at lower bulk concentrations than the maltosides and equilibrate at higher adsorbed amounts above the cmc. When compared with the ethylene oxide (EO) surfactants, it is confirmed that the EO surfactants hardly adsorb on titania, since the measured changes in the ellipsometric angles are within the noise level. They do, however, adsorb strongly on silica.     

Adsorption behavior of hydrophobin and hydrophobin/surfactant mixtures at the air-water interface

The adsorption of the surface-active protein hydrophobin, HFBII, and the competitive adsorption of HFBII with the cationic, anionic, and nonionic surfactants hexadecyltrimethylammonium bromide, CTAB, sodium dodecyl sulfate, SDS, and hexaethylene monododecyl ether, C(12)E(6), has been studied using neutron reflectivity, NR. HFBII adsorbs strongly at the air-water interface to form a dense monolayer ～30 ? thick, with a mean area per molecule of ～400 ?(2) and a volume fraction of ～0.7, for concentrations greater than 0.01 g/L, and the adsorption is independent of the solution pH. In competition with the conventional surfactants CTAB, SDS, and C(12)E(6) at pH 7, the HFBII adsorption totally dominates the surface for surfactant concentrations less than the critical micellar concentration, cmc. Above the cmc of the conventional surfactants, HFBII is displaced by the surfactant (CTAB, SDS, or C(12)E(6)). For C(12)E(6) this displacement is only partial, and some HFBII remains at the surface for concentrations greater than the C(12)E(6) cmc. At low pH (pH 3) the patterns of adsorption for HFBII/SDS and HFBII/C(12)E(6) are different. At concentrations just below the surfactant cmc there is now mixed HFBII/surfactant adsorption for both SDS and C(12)E(6). For the HFBII/SDS mixture the structure of the adsorbed layer is more complex in the region immediately below the SDS cmc, resulting from the HFBII/SDS complex formation at the interface.     

Influences of surfactant and nanoparticle assembly on effective interfacial tensions

We have studied assembly at air-water and liquid-liquid interfaces with an emphasis on systems containing both surfactants and nanoparticles. Anionic surfactants, sodium dodecyl sulfate (SDS) and non-ionic surfactants, Triton X-100 and tetraethylene glycol alkyl ethers (C(8)E(4), C(12)E(4) and C(14)E(4)), effectively decrease the surface tension of air-water interfaces. The inclusion of negatively charged hydrophilic silica nanoparticles (diameters of approximately 13 nm) increases the efficiency of the SDS molecules but does not alter the performance of the non-ionic surfactants. The former is likely due to the repulsive Coulomb interactions between the SDS molecules and nanoparticles which promote the surfactant adsorption at air-water interfaces. For systems involving trichloroethylene (TCE)-water interfaces, the SDS and Triton X-100 surfactants effectively decrease the interfacial tensions and the nanoparticle effects are similar compared to those involving air-water interfaces. Interestingly, the C(12)E(4) and C(14)E(4) molecules, with or without the presence of nanoparticles, fail to decrease the TCE-water interfacial tensions. Our molecular dynamics simulations have suggested that the tetraethylene glycol alkyl ether molecules tend to disperse in the TCE phase rather than adsorb at the TCE-water interfaces.