Preparation and Properties of New Ester-Linked Cleavable Gemini Surfactants

We have prepared a series of novel gemini surfactants having ester bonds in their structures. These surfactants possess two identical hydrophilic polyethylene glycol moieties, two hydrophobic alkyl group moieties, and an anionic spacer. The structures of these compounds were confirmed through infrared and nuclear magnetic resonance spectroscopic and elemental analyses. The novel gemini surfactants exhibit excellent surface activity in terms of their surface tension, low-foaming, wetting power, and fluorescence properties. The presence of the ester linkages made these structures cleavable surfactants.     

Preparation and properties of novel water‐soluble surfactants. I. Synthesis and surface activity of polycarboxylated multihydrophilic surfactants

A series of novel surfactants containing multianionic and nonionic hydrophilic moieties were prepared by reacting fumaric acid with polyoxyethylenated stearyl ether in the presence of a peroxy‐type free radical initiator to form a carboxylic‐acid‐group‐containing addition product. The structure of these surfactants was confirmed by infrared, nuclear magnetic resonance, and elemental analysis. These surfactants exhibit excellent functional properties of self‐sequestering. This means that besides good surfactant properties, including surface tension, foaming, and wetting, they possess autonomous sequestering ability without any help of additional sequestering agent. When used in cotton bleaching procedures, these surfactants increase the penetration of the fibers of gray fabrics and increase the whiteness of bleached cotton. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3559–3564, 2006     

Preparation and surface activity of biodegradable polymeric surfactants. I. Preparation and surface activity of dextrin derivatives

Novel dextrin derivative surfactants containing a modified glucoside structure have been prepared in which propylene glycol polyglucosides are reacted with a hydrophobic oxirane‐containing material of glycidyl ether with C10–C18 carbon atoms. These surfactants exhibit good surface activities, including surface tension, low foaming, and wetting power. These surfactants also have a good ability to improve the whiteness and wetting power of cotton fabrics in a hydrogen oxide bleaching system. The benefits of these dextrin derivative surfactants are their highly biodegradable properties, which are lacking in traditional surfactants.     

Synthesis and evaluation of new imidazolium‐based aromatic ether functionalized cationic mono and gemini surfactants

Synthesis of a novel series of imidazolium‐based surfactants, [(ROArCH₂MIm)Br] with aromatic ether functionalized hydrophobic tail of varying chain lengths and also their gemini counterparts were conducted in the present work. Synthesis involves initial conversion of 4‐hydroxy benzoic acid to its methyl ester followed by its O‐alkylation with long chain fatty alcohols, which was subsequently reduced and brominated to get 4‐alkyloxy benzyl bromide. For the synthesis of monocationic surfactant, 4‐alkyloxy benzyl bromide is quaternized with N‐methylimidazole. Gemini surfactants are synthesized by initial coupling of imidazole to 4‐alkyloxy benzyl bromide followed by its quaternization with dibromoalkane. The surface properties of all the synthesized surfactants were determined using surface tensiometry. Within the same homologous series, expected decrease in critical micelle concentration (cmc) with the increase in hydrophobicity was observed for shorter chain homologs. However, the deviation in cmc value from regularity was observed when the number of carbon atoms in the hydrophobic chain exceeded a certain number. The cmc values of the geminis were found to be remarkably low compared to their monomeric counterparts.     

蛋白质-表面活性剂组装结构的分子模拟

采用Langevin分子动力学方法模拟β模型蛋白与表面活性剂在溶液中形成的各种组装结构,考察了表面活性剂疏水性强度与浓度对蛋白质分子构象的影响.结果显示：弱疏水性表面活性剂可以在蛋白质表面自组装形成限制性空间,使被包覆的蛋白质的立体结构更为稳定;强疏水性的表面活性剂则可以与蛋白质疏水核心区的疏水基团形成复合物,而使蛋白质的立体结构被破坏,即蛋白质发生去折叠.上述模拟可再现相关实验结果,其展现的蛋白质结构转换微观图景对于表面活性剂的分子设计及其应用于生物加工过程具有指导作用.     

反胶团酶催化研究新进展

评述了近年来反胶团酶催化研究的新进展。在AOT/异辛烷反胶团中加入非离子型表面活性剂如Tween 85、小相对分子质量聚乙二醇等可有效降低酶与表面活性剂间的静电和疏水作用 ,显著提高酶的活性。对AOT进行化学修饰及合成结构与磷脂类似的新表面活性剂以用其构建新的反胶团体系 ,酶的活性较常用的AOT/异辛烷反胶团体系有显著提高。在反胶团酶反应动力学研究中考虑水含量或底物在反胶团表面吸附的影响等 ,提出了进一步研究的设想 ,包括开发新型表面活性剂以进一步提高酶的活性和稳定性及有利于产物分离     

Influence of varying surface hydrophobicity of chitosan membranes on the adsorption and activity of lipase

The hydrophobic surface modification of chitosan membranes was performed using the amidating reaction of amino groups on a membrane surface with stearic acid activated by 1‐ethyl‐3‐(3‐dimethylaminopropyl)‐carbodiimide hydrochloride (EDC) and N‐hydroxysuccinimide (NHS). The varying surface hydrophobicity of chitosan membranes was achieved by changing the degree of amidation and evaluated by the water contact angle analysis and the adsorption experiment of the hydrophobic dye, Rose Bengal. The effects of the surface hydrophobicity of chitosan membranes on the adsorption behaviors, activity and stability of Candida rugosa lipases were investigated. The experimental results suggested that the increased surface hydrophobicity of chitosan membranes improved the adsorption capacity and activity of the immobilized lipase. The modified chitosan membranes with 30.36% amidation exhibited the maximum activity retention of 83.87%. In addition, a desirable thermal stability was also achieved for the adsorbed lipase. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Polydimethylsiloxanes-modified TiO2 coatings: The role of structural,morphological and optical characteristics in a self-cleaning surface

The surface modification of TiO₂ thin film with hydrophobic agents has been a good strategy for modulation properties of this versatile material, allowing it to be compatible with a wider range of applications. This is a promising approach in the developing of improved self-cleaning materials; since films prepared with this modification are expected to exhibit photocatalytic and hydrophobic properties. However, these strategies still need to be improved, seeking the design of hydrophobic and photocatalytic structures through faster and simpler procedures, using non-fluorinated polymers. This work proposed the synthesis and characterization of self-cleaning coatings, involving a polydimethylsiloxane (PDMS)/TiO₂ system. TiO₂ thin films were modified with two different types of PDMS: hydroxyl and vinyl-terminated – and prepared by two distinct routes: Route A, which involved a modified TiO₂ sol-gel process, and route B, consisting in the functionalization of TiO₂ films after their calcination. Each route was best suited for a different type of PDMS. The PDMS modification occurred by a covalent linkage, which can allow a better durability of the functionalization on TiO₂ surface. In some cases, the functionalization was heterogeneous and promoted a significant increase in surface roughness, allowing these samples to present hydrophobicity and photocatalytic activity.     

脂肪酸双酯双磺酸盐型双子表面活性剂的合成及性能

以脂肪酸、二甘醇、氯磺酸为原料,经酯化、磺化反应制备了4种二甘醇双(α-磺酸钠)烷基羧酸酯表面活性剂。用红外光谱、元素分析对产物进行了表征,并对其表面活性和聚集行为进行了研究。结果表明,该类脂肪酸双酯双磺酸盐型双子表面活性剂比十二烷基硫酸钠的临界胶束浓度低1～2个数量级和更强的降低表面张力的能力。稳态荧光猝灭实验表明,表面活性剂胶束聚集数随着烷烃链碳原子数的增加而逐渐减小。     

Hydrophobic composite coatings with photocatalytic self-cleaning properties by micro/nanoparticles mixed with fluorocarbon resin

A newly developed hydrophobic composite coating was fabricated by incorporating modified TiO₂ nanoparticles and hydrophobic material polytetrafluoroethylene (PTFE) micropowders dispersed in fluorocarbon resin. Moreover, the surface characteristics and self-cleaning properties of the newly developed composite material were examined. The material was found to exhibit sufficient hydrophobicity with a water contact angle of 133°. The surface free energy of the composite coating was 4.11 mJ/m². Scanning electron microscopy results revealed a micro/nanocomposite structure composed of PTFE micropowders and TiO₂ nanoparticles, which was verified by X-ray photoelectron spectroscopy results. Through ultraviolet irradiation the modified TiO₂-PTFE/FEVE composite coating successfully removed oleic acid absorbed on its surface. These results showed that the functional composite coating had a sufficiently hydrophobic surface with an efficient self-cleaning effect.     

Study on the rheological behavior of the hydrophobically modified hydroxyethyl cellulose with 1,2‐epoxyhexadecane*

Through the macromolecule reaction method, the hydrophobically modified hydroxyethyl cellulose (EP16–HAHEC) was synthesized using 1, 2‐epoxyhexadecane as the hydrophobic monomer. The solution properties of EP16–HAHEC were comprehensively investigated, which showed that the polymer with enhanced; viscosification property, thermal stability, shear resistance, and salt resistance was obtained. Amphiphilic structure of EP16–HAHEC molecules contributed to the surface activity of the polymer. By forming complex solution with surfactants or carboxylmethyl cellulose (CMC), the viscosification property of EP16–HAHEC could be enhanced through the interactions of hydrophobic groups and hydrogen bonds. The viscosity‐enhancing mechanism of HAHEC was studied by the environment scan electronic microscope (ESEM) and the fluorescence spectrum measurements, which demonstrated that the formation of the supramolecular aggregation networks was coincident with the increase of the apparent viscosity of HAHEC. With the gradual formation of the complete polymer molecule networks, the apparent viscosity rised dramatically, and the associating aggregations of the polymer molecules appeared far before the great change of the macroproperty of the polymer. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2953–2959, 2006     

A facile strategy to improve the encapsulation efficiency of polymer microcapsules containing water‐soluble salt cores

To increase the encapsulation efficiency of microcapsules composed of water‐soluble salt cores and hydrophobic material shells, we herein reported a facile and versatile strategy to improve the hydrophobicity of water‐soluble salts [i.e., ammonium persulfate (APS)] by surface modification of APS using oleic acid or silane coupling agent, respectively. The results confirmed that the hydrophobicity of the two modified APS had been successfully improved compared with that of non‐modified APS. Moreover, the two modified APS could be effectively encapsulated into hydrophobic polystyrene and the encapsulation efficiency of the resulting microcapsules goes up significantly. This study was expected to drive progress in the preparation technology of microcapsules which comprise water‐soluble salts as cores and hydrophobic polymer materials as shells in many industrial application fields. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45294.     

Preparation and Surface Activity of Phosphated Alkyl Oligoglucosides

A family of phosphated alkyl oligoglucoside surfactants was prepared by reacting alkyl oligoglucosides with phosphorus oxychloride. The alkyl oligoglucosides were obtained by an usual method in which the glucose is reacted with a fatty alcohol containing 10–18 carbon atoms. These novel phosphated surfactants have been found to exhibit good surface tension, foaming and wetting power. The critical micelle concentration was found to increase with the length of hydrocarbon chain of the surfactant. The surface excess concentration and the interfacial area per surfactant molecule are reported. These phosphated surfactants also exhibit a good performance to improve the whiteness and wetting of cotton fabrics in a hydrogen oxide bleaching system, and they are also found to be more biodegradable than conventional surfactants.     

Emulsifying performance of modular beta-sandwich proteins: the hydrophobic moment and conformational stability

Our understanding of protein emulsifying properties is largely based on analysis of emulsifiers found in milk and seed. The 9th-10th type III fibronectin domain pair retains full biological activity following emulsification-encapsulation into polyester microspheres, for controlled delivery, but the conformational criteria determining emulsification efficiency (EE) are unknown. Here, we have generated a series of mutants of this beta-sandwich protein, changing the hydrophobic moment and conformational stability, to investigate the structure-emulsification relationship. Predictive modelling of the hydrophobic moment of beta-strands and mutations known to increase conformational stability were used to generate the series. The proteins were tested for their emulsion stability and EE for oil-in-water mixtures. We show that the stabilization of emulsions by beta-sandwich proteins is best predicted by conformational stability during equilibrium denaturation in ionic surfactant. In contrast, the EE of these proteins is inversely related to an increase in their surface hydrophobicity following unfolding in surfactant. We also describe a novel beta-sandwich emulsifier with strong EE. The requirement for interdomain flexibility to achieve maximum emulsion stability and EE is also shown. This work increases our understanding of the mechanisms involved in protein emulsification and will be of use to the microencapsulation of proteins into polyester microspheres via emulsion-extraction protocols.     

Synthesis,Characterization, Surface and Biological Activity of Diquaternary Cationic Surfactants Containing Ester Linkage

Two series of diquaternary cationic surfactants designated as E9Nm and E11Nm having two different alkyl chains in their chemical structure were synthesized. The chemical structures of these surfactants were confirmed using elemental analysis, FTIR and ¹H‐NMR spectra. The surface activities of the different surfactants were determined using surface and interfacial tension at 25 °C. The surface parameters including: critical micelle concentration, effectiveness, efficiency, maximum surface excess and minimum surface area were determined. The surface activities of the cationic surfactants were correlated with their chemical structure. The surface activities of the surfactants increased with increasing the hydrophobic chain length. The adsorption and micellization tendencies of the surfactants in solution were determined using the free energies of adsorption and micellization. The synthesized surfactants were evaluated as biocides against bacteria and fungi. Biocidal activity data showed that a gradual increase in the hydrophobic chain length of the surfactant molecules gradually increases the efficiency of these surfactants as biocides.     

Preparation and Surface Activities of Modified Soy Protein–Dextrin Surfactants

A series of polymeric surfactants has been prepared through the reaction of soy protein with polyethoxylated stearyl ethers of various hydrophilic chain lengths. These surfactants exhibited surface activity, evaluated using surface tension, foaming, and wetting power that was superior to that of traditional surfactants containing only one hydrophobic moiety and one hydrophilic head group. Changing the ethoxylate (EO) group length had a significant effect on the surface activity. Increasing the EO group length decreased the critical micelle concentration (CMC) and increased the surface tension at the CMC (γ_CMC). The good surface properties of these polysaccharide/protein‐type surfactants suggest that they could be used as emulsifiers to prepare oil‐in‐water emulsions displaying good stability.     

Effects of hydrophobic interaction on rheological behavior and microstructure of carboxylated core‐shell latex suspension

We have investigated the effects of hydrophobic interactions on the rheological behavior and microstructure of suspension of carboxylated core‐shell latex particles with changing hydrophobicity of shell polymer and suspending medium. The carboxylated core‐shell latex particles formed lattice‐like microstructures in aqueous suspension with dissociation of carboxyl groups. With increasing hydrophobicity of the shell polymer, the interparticle distance ξ in the microstructure decreased. However, ξ increased with increasing hydrophobicity of the suspending medium. The effect of hydrophobic interaction on ξ was explained by the steric stabilization theory for particles with grafted polymer on the surface. As the carboxylated core‐shell latex particles overlapped each other in the microstructure, an attractive force was generated between the particles in aqueous suspension. With increasing hydrophobicity of the shell, the attractive force increased, but with increasing hydrophobicity of the suspending medium, the attractive force decreased. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4153–4158, 2006     

The Modification of Chrome Tanned Leather by Polyethylene Glycol-Linked Gemini Fatty Alcohol Phosphate

A series of polyethylene glycol-linked Gemini fatty alcohol phosphate surfactants (GFAP) were prepared with long chain n-alkanol (C = 8, 12, 16, 18), polyethylene glycol (PEG-200, PEG-400, PEG-600, PEG-800, PEG-1000) and phosphorus oxychloride (POCl₃). The structure of the prepared surfactants was characterized by Fourier transform infrared spectrometer (FT-IR). The surfactants were employed for the modification of chrome-tanned leather. The morphological changes of chrome-tanned leather and modified chrome-tanned leather were observed by scanning electron microscopy (SEM). The relationship between the alkyl chain length and molecular weight of the PEG and the hydrophobicity, softness, mechanical strength of modified chrome-tanned leather was also discussed. The experimental results showed that the mechanical strength and softness of modified chrome-tanned leather were enhanced with an increase of alkyl chain length, while the hydrophobicity, mechanical strength and softness were decreased with an increase of molecular weight of the PEG. The hydrophobicity, mechanical strength and softness of modified chrome-tanned leather were optimized for an alkyl chain length of 16. Therefore, 16–200 Gemini phosphate surfactants with an alkyl chain length of 16 and a PEG molecular weight of 200 have a good comprehensive modification effect on Chrome-tanned leather, the tensile strength, tear strength and softness of modified chrome-tanned leather are 57.07 N mm⁻², 79.49 N mm⁻¹, 9.73 mm, respectively.     

Screening for Potential Antimicrobial Activities of Some Cationic Uracil Biocides Against Wide-Spreading Bacterial Strains

Eight novel uracil-based cationic surfactants containing Schiff base species were synthesized and characterized using elemental analysis, FTIR, ¹H-NMR and ¹³C-NMR spectroscopy. The surface activities of the synthesized Schiff bases and their cationic derivatives were determined based on interfacial tension measurements and partition coefficient values in water/octanol system. The synthesized Schiff bases and their cationic derivatives were evaluated as novel biocides against different bacteria and fungi strains. The results showed that the biocidal activity of the synthesized Schiff bases was considerably increased by quaternization. The influence of the cationic surfactants as biocides was increased by increasing the hydrophobic chain length and the presence of the methoxy groups. The biocidal activity was also increased by increasing the partition coefficient in water/octanol system. The structure and surface activity/biocidal activity of the different compounds were discussed.     

Synthesis and properties of destructible anionic and cationic surfactants with a 1,3-dioxolane ring

A convenient synthetic method for the preparation of destructible surfactants containing a 1,3-dioxolane ring with various substituents is described. The substituents include carboxylate, quaternary ammonium, and several aliphatic alkyl groups, such as hydrophilic or hydrophobic groups. These novel surfactants had good surface activity, and were easily hydrolyzed under acidic conditions. They also catalyzed aliphatic halide substitution.