表面活性剂对纤维素接枝共聚物溶液粘度性质的影响

研究了阴离子十二烷基硫酸钠(SDS)、阳离子十六烷基三甲基溴化铵(CTAB)和非离子聚乙二醇辛基苯基醚(OP)等三种不同类型的表面活性剂对疏水化水溶性两性纤维素接枝共聚物(CGAO)溶液粘度性质的影响.结果表明,在SDS和OP的临界胶束浓度(cmc)附近，CGAO溶液粘度最大，SDS引起CGAO粘度的变化大于OP；即使在CTAB的cmc附近，随着CTAB浓度的增加，CGAO的粘度一直呈下降趋势；非疏水改性的纤维素接枝共聚物的溶液粘度随SDS或CTAB浓度的增加而下降，但几乎不随OP浓度的增大而变化.此外，通过凝胶渗透色谱法测得的保留时间证实了SDS、CTAB和OP与CGAO之间的疏水缔合作用.     

十六烷基三甲基溴化铵/油酸钠混合体系蠕虫状胶束流变性研究

阴、阳离子表面活性剂之间强烈的相互作用利于形成自由弯曲的蠕虫状胶束。本文利用阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)和阴离子表面活性剂油酸钠(Na OA)制备了CTAB/Na OA蠕虫状胶束,研究了两表面活性剂的混合比和表面活性剂总浓度的变化对蠕虫状胶束体系稳态流变性及动态粘弹性的影响。结果表明,蠕虫状胶束在剪切过程中的解缠、拟网状结构的破坏以及最终沿剪切速度方向取向等是蠕虫状胶束产生剪切稀释特性的原因。两表面活性剂的混合比和表面活性剂总浓度的变化导致表面活性剂之间的静电作用、疏水作用发生较大的变化,最终引起体系内部表面活性剂聚集体形态的差异。体系内蠕虫状胶束长度、体系结构复杂程度、蠕虫状胶束形成的网络结构的致密度等都影响着体系的流变行为。在混合比R=3.6、总浓度CT=0.24mol/L时,体系中蠕虫状胶束最长,网络结构最为紧密,体系的零剪切粘度达到最大值。表面活性剂浓度一定时,混合比的提高有助于蠕虫状胶束的定向生长,弛豫时间τR和储能模量高频区平台模量G0提高,R=3.6时两者皆达到极大值,此后由于蠕虫状胶束的分枝化及(或)胶束破裂导致τR及G0下降。在表面活性剂混合比一定(R=3.6)时,表面活性剂浓度的提高利于蠕虫状胶束的增长或者分枝化,增加了胶束网络结构缠绕(融合)点的密度,导致G0逐渐增大。Cole-Cole图证实本文研究的蠕虫状胶束体系是符合Maxwell模型的线性粘弹性流体。     

芘荧光探针法研究海藻酸钠与SDS的作用

采用芘荧光法研究了海藻酸钠(NaAlg)与十二烷基硫酸钠(SDS)在不同pH水溶液中的相互作用.以芘单体的荧光光谱第一峰与第三峰的荧光强度之比(I1/I3)及激基缔合物与单体荧光强度之比(IE/IM)来探测芘分子所处环境的极性.结果表明:NaAlg水溶液随pH值降低,出现了聚合物的疏水微区;pH从7降到5,NaAlg类似简单盐,对SDS的临界胶束浓度(CMC)有明显的影响;在pH 3时,海藻酸主链上有足够的疏水片段,使得SDS与海藻酸通过疏水性作用而聚集.NaCl对NaAlg /SDS体系的影响亦较明显.     

新型疏水缔合聚合物P(AM/POEA)与表面活性剂的相互作用

采用粘度法、荧光探针和透射电镜研究了新型疏水缔合聚合物P(AM/POEA)和表面活性剂SDS和CTAB在水溶液中的相互作用. 聚合物P(AM/POEA)结构中, 疏水体(2-苯氧乙基丙烯酸酯)呈嵌段状无序地分布在聚丙烯酰胺主链上. 这类聚合物很容易和表面活性剂相互作用, 通过疏水缔合, 形成混合胶束状聚集体, 导致溶液粘度剧增. 随聚合物溶液中SDS的加入, 溶液粘度发生大幅度起伏变化, 出现最大值. 粘度最大值对应的表面活性剂浓度c_S,max位于表面活性剂CMC附近, 并发现它的位置不随聚合物微结构而变化. 然而它们缔合作用的增粘程度却与聚合物疏水体含量X_H及疏水嵌段尺寸N_H有关. 在实验浓度范围内, X_H和N_H愈大, 溶液的粘度越高. 此外用透射电镜直接观察到聚合物/表面活性剂体系中聚集体的交联结构形貌.     

聚(丙烯酰胺/丙烯酸钠/N,N-二辛基丙烯酰胺)与表面活性剂的相互作用

利用粘度法研究了孪尾疏水缔合水溶性聚(丙烯酰胺/丙烯酸钠/N,N-二辛基丙烯酰胺)[P(AM/NaAA/D iC8AM)]与表面活性剂十二烷基硫酸钠(SDS)、十六烷基三甲基溴化铵(CTAB)、壬基酚聚氧乙烯醚(OP-10)的相互作用。研究表明SDS、CTAB的加入,能显著地降低P(AM/NaAA/D iC8AM)水溶液的临界缔合浓度。表明P(AM/NaAA/D iC8AM)与SDS、CTAB的疏水缔合作用较强,而与OP-10的疏水缔合作用较弱。     

有机电解质在胶束催化聚苯乙烯氯甲基化反应中的作用

在实施聚苯乙烯氯甲基化反应的胶束催化体系中加入四丁基溴化铵 ((Bu)₄NBr, TBAB), 研究了有机电解质TBAB对胶束催化反应的影响规律. 实验结果表明, 在非离子表面活性剂NP-10及阴离子表面活性剂SDS的胶束催化体系中, TBAB的加入使聚苯乙烯氯甲基化反应的速率明显增大, 前者尤为突出；而在阳离子表面活性剂CTAB的胶束催化体系中, TBAB的加入几乎对反应速率无促进作用. 这种结果一方面归因于加入电解质TBAB会降低SDS的临界胶束浓度, 从而增强对聚苯乙烯四氯化碳溶液的增溶能力；更主要的原因是TBAB的丁基与表面活性剂碳氢链间的疏水相互作用会使季铵离子(Bu)₄N⁺嵌入SDS的胶束之中, 结合到NP-10的胶束表面, 使SDS胶束的阴离子头基对亲核取代反应(控制步骤)的禁阻作用得以减缓, 使NP-10的胶束表面携带了正电荷, 显著促进亲核取代反应的进行, 而对于CTAB的胶束, 由于静电排斥作用, 季铵离子(Bu)₄N⁺不能接近CTAB的胶束, 故TBAB的加入对聚苯乙烯氯甲基化反应不产生作用.     

苄泽类非离子表面活性剂与离子型表面活性剂复配性质研究

通过测定苄泽类非离子型表面活性剂Brij58、Brij76、Brij78与阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)、阴离子表面活性剂十二烷基硫酸钠(SDS)复配体系的表面张力,研究了复配体系的形成胶束能力、降低表面张力效率、降低表面张力能力3种增效作用,并结合复配体系中表面活性剂分子间的相互作用参数进行了深入的讨论。研究结果表明,与阳离子表面活性剂复配时,Brij76/CTAB体系增效作用最强;与阴离子表面活性剂复配时,Brij58/SDS复配体系增效作用最强,而且苄泽类非离子型表面活性剂与阴离子表面活性剂复配增效作用更加显著。     

吲哚方酸菁染料在表面活性剂水溶液中的光降解

考察了4种含有不同N位取代基的对称吲哚方酸菁染料在阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)、阴离子表面活性剂十二烷基硫酸钠(SDS)和非离子表面活性剂曲拉通(TX-100)水溶液中的光降解行为,结果表明,表面活性剂对染料分子具有保护作用,其影响大小为CTAB>TX-100>SDS,分子中有羧基的染料受影响程度最大。在表面活性剂浓度较低时,染料光降解程度随着表面活性剂浓度的增加而增加,但形成胶束后,染料的光降解程度则随着表面活性剂浓度的升高而降低。     

微嵌段疏水缔合聚合物/十二烷基硫酸钠溶液体系的流变特性

研究了疏水微嵌段长度和阴离子表面活性剂十二烷基硫酸钠(SDS)对聚/表体系的流变性的影响。研究表明,微嵌段长度对疏水缔合聚合物溶液的粘性有较大影响,嵌段越长聚合物越容易发生分子间缔合其溶液粘度越大。随着SDS的加入,各聚/表体系粘度短期内出现一个极值,然后降至一个稳定值,嵌段长度越长,其极值点越大。聚合物与SDS体系表现出的剪切增稠和粘弹性特征也随嵌段长度增加而增大。通过研究不同体系平台区模量(G0)和特征松弛时间(TR)的变化规律,发现嵌段长度和SDS含量对聚/表体系物理交联缔合点的密度有较大影响,对缔合点强度影响较小。本文有助于更好地解释微嵌段疏水缔合聚合物与表面活性剂相互作用的内在因素。     

SDS/CTAB/H2O体系特异性质研究

对SDS/CTAB/H2O系统的三元相行为,导电能力,粘度性质等进行了相关性研究,发现相图中存在两个规则的液晶区。当SDS/CTAB(摩尔比)接近1∶2或2∶1时,其混合水溶液中表面活性剂分子异种电荷间的静电引力作用和同种电荷间的静电斥力作用达到吻合状态,既不易形成以胶束为主的均相溶液体系,也不易形成沉淀,而是形成远程有序组合体-液晶结构。当表面活性剂总浓度一定时,具有液晶结构的SDS/CTAB混合水溶液体系,致使体系的导电能力及粘度均呈现极大值。     

Spectrophotometric study of interaction and solubilization of procaine hydrochloride in micellar systems

The interaction of Procaine hydrochloride (PC) with cationic, anionic and non-ionic surfactants; cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS) and triton X-100, were investigated. The effect of ionic and non-ionic micelles on solubilization of Procaine in aqueous micellar solution of SDS, CTAB and triton X-100 were studied at pH 6.8 and 29°C using absorption spectrophotometry. By using pseudo-phase model, the partition coefficient between the bulk water and micelles, K_x, was calculated. The results showed that the micelles of CTAB enhanced the solubility of Procaine higher than SDS micelles (K_x = 96 and 166 for SDS and CTAB micelles, respectively) but triton X-100 did not enhanced the solubility of drug because of weak interaction with Procaine. From the resulting binding constant for Procaine-ionic surfactants interactions (K_b = 175 and 128 for SDS and CTAB surfactants, respectively), it was concluded that both electrostatic and hydrophobic interactions affect the interaction of surfactants with cationic procaine. Electrostatic interactions have a great role in the binding and consequently distribution of Procaine in micelle/water phases. These interactions for anionic surfactant (SDS) are higher than for cationic surfactant (CTAB). Gibbs free energy of binding and distribution of procaine between the bulk water and studied surfactant micelles were calculated.      

The Viscous Properties of Anionic/Cationic and Cationic/Nonionic Mixed Surfactant Systems

The behavior of mixed cationic/anionic and cationic/nonionic surfactants solutions have been studied by viscosimetry. The systems studied were sodium dodecyl sulfate (SDS)/cetyltrimethylammonium bromide (CTAB) and CTAB/Brij (polyoxyethylene lauryl ether, n = 10 and 23) in aqueous and sodium chloride solutions. The relative viscosity of single nonionic surfactant solutions is larger than that of SDS or CTAB solutions. It increases with the number of ethylene oxide groups. In the mixed systems, viscosity deviates from ideal behavior. The deviation results from electrostatic interactions. The surfactant mixture composition affects the self-assembled microstructure and rheology. A new mixed system that forms clear micellar solution above CMC was detected. In CTAB/Brij systems, the experimental data also deviate from ideal behavior due to mixed micelle formation and electroviscous effect. This effect is less pronounced than that of SDS/CTAB system and could be suppressed by adding an electrolyte (NaCl).     

Depletion flocculation of latex dispersion in ionic micellar systems

The flocculation behavior of anionic and cationic latex dispersions induced by addition of ionic surfactants with different polarities (SDS and cetyltrimethylammonium bromide (CTAB)) have been evaluated by rheological measurements. It was found that in identical polar surfactant systems with particle surfaces of SDS + anionic lattices and CTAB + cationic lattices, a weak and reversible flocculation has been observed in a limited concentration region of surfactant, which was analyzed as a repletion flocculation induced by the volume-restriction effect of the surfactant micelles. On the other hand, in oppositely charged surfactant systems (SDS + cationic lattices and CTAB + anionic lattices), the particles were flocculated strongly in a low surfactant concentration region, which will be based on the charge neutralization and hydrophobic effects from the adsorbed surfactant molecules. After the particles stabilized by the electrostatic repulsion of adsorbed surfactant layers, the system viscosity shows a weak maximum again in a limited concentration region. This weak maximum was influenced by the shear rate and has a complete reversible character, which means that this weak flocculation will be due to the depletion effect from the free micelles after saturated adsorption.     

流变学法研究表面活性剂与HPAM的相互作用

流变学法研究表面活性剂与HPAM的相互作用;聚合物;表面活性剂;相互作用;流变学方法     

Interaction between silicates and ionic surfactants in dilute solution

Understanding the interaction between silicate ions and surfactants is critical for the design and development of mesoporous siliceous materials. We examined the interaction between sodium silicate ions and three different cationic surfactants [namely, cetyltrimethylammonium bromide (CTAB), tetradecyltrimethylammonium bromide (TTAB), and dodecyltrimethylammonium bromide (DTAB)] and an anionic surfactant [sodium dodecyl sulfate (SDS)] in dilute solution at room temperature. From the combination of several techniques, such as conductometric and potentiometric titrations, dynamic light scattering, and isothermal titration calorimetry, the phase behavior of the sodium silicate and CTAB system was determined. We observed that the aggregation behavior of the silicate-CTAB system is similar to that of a polymer-surfactant system. The formation of the silicate-CTAB complex is induced by the adsorption of SiOH and SiO- groups, aided by CTAB unimers. The electrostatic attraction and hydrophobic interaction are the dominant forces controlling the formation of silicate-CTAB complexes. When these complexes are saturated with CTAB unimers, free CTAB micelles are then produced. TEM micrographs revealed that a stable Si-O-Si network is absent within the silicate-CTAB complexes, and surprisingly, stable silicate-CTAB complexes with ordered structure were observed. The present finding is important for understanding the interaction between silicate and surfactant in the synthesis of mesoporous structure in the dilute solution regime.     

树枝聚醚改性聚丙烯酰胺和阴离子表面活性剂的缔合行为

采用粘度法、荧光探针技术和^1H NMR驰豫和自扩散方法，研究了树枝聚醚疏 水改性丙烯酰胺共聚物(PDAM)和十二烷基硫酸钠(SDS)在水溶液中的相互作用．这 种共聚物含有少量的树枝聚醚，具有疏水性，容易和SDS发生相互作用，在表面活 性剂浓度远低于临界胶束浓度(cmc)的情况下，生成混合胶束状聚集体．它们的缔 合行为和溶液性质明显地取决于表面活性剂的浓度，随着聚合物溶液中加入SDS， 溶液粘度发生急剧变化，并在较低的表面活性剂浓度处出现很大的最高点．荧光和 ^1H NMR测定结果表明，这是由于在不同SDS浓度范围内，PDAM/SDS形成的聚集体结 构不同的缘故．     

Mixed micelles of polyethylene glycol (23) lauryl ether with ionic surfactants studied by proton 1D and 2D NMR

(1)H NMR chemical shift, spin-lattice relaxation time, spin-spin relaxation time, self-diffusion coefficient, and two-dimensional nuclear Overhauser enhancement (2D NOESY) measurements have been used to study the nonionic-ionic surfactant mixed micelles. Cetyl trimethyl ammonium bromide (CTAB) and sodium dodecyl sulfate (SDS) were used as the ionic surfactants and polyethylene glycol (23) lauryl ether (Brij-35) as the nonionic surfactant. The two systems are both with varying molar ratios of CTAB/Brij-35 (C/B) and SDS/Brij-35 (S/B) ranging from 0.5 to 2, respectively, at a constant concentration of 6 mM for Brij-35 in aqueous solutions. Results give information about the relative arrangement of the surfactant molecules in the mixed micelles. In the former system, the trimethyl groups attached to the polar heads of the CTAB molecules are located between the first oxy-ethylene groups next to the hydrophobic chains of Brij-35 molecules. These oxy-ethylene groups gradually move outward from the hydrophobic core of the mixed micelle with an increase in C/B in the mixed solution. In contrast to the case of the CTAB/Triton X-100 system, the long flexible hydrophilic poly oxy-ethylene chains, which are in the exterior part of the mixed micelles, remain coiled, but looser, surrounding the hydrophobic core. There is almost no variation in conformation of the hydrophilic chains of Brij-35 molecules in the mixed micelles of the SDS/Brij-35 system as the S/B increases. The hydrophobic chains of both CTAB and SDS are co-aggregated with Brij-35, respectively, in their mixed micellar cores.     

Adsorption behavior of hydrophobin and hydrophobin/surfactant mixtures at the solid-solution interface

The adsorption of surface-active protein hydrophobin, HFBII, and HFBII/surfactant mixtures at the solid-solution interface has been studied by neutron reflectivity, NR. At the hydrophilic silicon surface, HFBII adsorbs reversibly in the form of a bilayer at the interface. HFBII adsorption dominates the coadsorption of HFBII with cationic and anionic surfactants hexadecyltrimethyl ammonium bromide, CTAB, and sodium dodecyl sulfate, SDS, at concentrations below the critical micellar concentration, cmc, of conventional cosurfactants. For surfactant concentrations above the cmc, HFBII/surfactant solution complex formation dominates and there is little HFBII adsorption. Above the cmc, CTAB replaces HFBII at the interface, but for SDS, there is no affinity for the anionic silicon surface hence there is no resultant adsorption. HFBII adsorbs onto a hydrophobic surface (established by an octadecyl trimethyl silane, OTS, layer on silicon) irreversibly as a monolayer, similar to what is observed at the air-water interface but with a different orientation at the interface. Below the cmc, SDS and CTAB have little impact upon the adsorbed layer of HFBII. For concentrations above the cmc, conventional surfactants (CTAB and SDS) displace most of the HFBII at the interface. For nonionic surfactant C(12)E(6), the pattern of adsorption is slightly different, and although some coadsorption at the interface takes place, C(12)E(6) has little impact on the HFBII adsorption.