Carbon-based perovskite solar cells show great potential owing to their low-cost production and superior stability in ambient air.However,scaling up to high-efficiency carbon-based solar modules hinges on reliable dep...Carbon-based perovskite solar cells show great potential owing to their low-cost production and superior stability in ambient air.However,scaling up to high-efficiency carbon-based solar modules hinges on reliable deposition of uniform defect-free perovskite films over large areas,which is an unsettled but urgent issue.In this work,a long-chain gemini surfactant is introduced into perovskite precursor ink to enforce self-assembly into a network structure,considerably enhancing the coverage and smoothness of the perovskite films.The long gemini surfactant plays a distinctively synergistic role in perovskite film construction,crystallization kinetics modulation and defect passivation,leading to a certified record power conversion efficiency of 15.46%with Voc of 1.13 V and Jsc of 22.92 mA cm^(-2)for this type of modules.Importantly,all of the functional layers of the module are printed through a simple and high-speed(300 cm min^(-1))blade coating strategy in ambient atmosphere.These results mark a significant step toward the commercialization of all-printable carbon-based perovskite solar modules.展开更多
The synthesis and surfactant activities of two new cationic gemini surfactants containing triazole compound as spacer were described. Their critical micelle concentrations (CMC), which are 1.8×10-4 mol/L and 3.9...The synthesis and surfactant activities of two new cationic gemini surfactants containing triazole compound as spacer were described. Their critical micelle concentrations (CMC), which are 1.8×10-4 mol/L and 3.9×10-4 mol/L respectively, are much lower than that of conventional surfactant cetyltrimethyl ammonium chloride (CTAC). In addition, compared with some gemini surfactants containing phenylene, xylylene and stilbenyl as spacer, this new kind of surfactants has good solubility in water at room temperature because of containing more hydrophilic groups or atoms in molecules.展开更多
Four gemini cationic surfactants {N,N′-di[2-(lauryldimethylamino)acetyl]polymethylenediamine dichloride, LAA-s-LAA, s=2,3,4,6} were synthesized by using four bis(α-chloroacetamide)s and N,N-dimethyllaurylamine, resp...Four gemini cationic surfactants {N,N′-di[2-(lauryldimethylamino)acetyl]polymethylenediamine dichloride, LAA-s-LAA, s=2,3,4,6} were synthesized by using four bis(α-chloroacetamide)s and N,N-dimethyllaurylamine, respectively. The molecular structures were characterized by means of IR, ~ 1H NMR, \{~ ~13 C NMR\} and MS, and the behavior of their aqueous solutions was studied. The critical micell concentrations(CMC) of LAA-s-LAA were one order of magnitude lower than that of dodecyltrimethyl ammonium chloride(DTAC). With the change of the length of spacer chain(s), their CMC values change, and CMC reaches the top value at s=4.展开更多
Interaction of anionic polyelectrolyte with cationic gemini surfactant has been investigated by coarse-grained molecular dynamics simulation.Polyelectrolyte facilitates the oppositely charged ionic surfactants to aggr...Interaction of anionic polyelectrolyte with cationic gemini surfactant has been investigated by coarse-grained molecular dynamics simulation.Polyelectrolyte facilitates the oppositely charged ionic surfactants to aggregate by suppressing the electrostatic repulsion between ionic head groups leading to the formation of micellar complex.With addition of surfactant,the conformation of polyion chain changes from stretched to random coiled to spherical,and at the same time more free micelles are formed by surfactants in mixtures.Increasing the length of spacer or tail chain in gemini surfactant will weaken its interaction with polyelectrolyte and simultaneously strengthen its tendency to self-assemble.The simulation results are consistent with experimental observations and reveal that the electrostatic interaction plays an important role in the interaction of polyelectrolyte with gemini sur- factant.展开更多
To search a novel class of effective silicate mineral collectors,the Gemini quaternary ammonium salt surfactant(butane-α,ω-bis(dimethyl dodeculammonium bromide),12-4-12) and its corresponding conventional monomeric ...To search a novel class of effective silicate mineral collectors,the Gemini quaternary ammonium salt surfactant(butane-α,ω-bis(dimethyl dodeculammonium bromide),12-4-12) and its corresponding conventional monomeric surfactant(dedecyl trimethyl ammonium bromide,DTAB) were adopted to comparatively study the flotation behaviors of illite,pyrophyllite and kaolinite. Three silicate minerals with the Gemini surfactant as collector reveal floatability far better than with the corresponding traditional one. At pH 6,the best recoveries of illite,pyrophyllite and kaolinite with 3.5×10-4 mol/L 12-4-12 are 99.2%,91.7% and 99.6%,respectively. The fluorescence and contact angle measurement were also conducted for the further investigation of surfactants aggregation behavior and silicate mineral surface hydrophobic properties. FTIR spectra analysis and electrokinetic analysis show that the mechanism of adsorption of collector molecules on mineral surfaces is almost identical for the electronic attraction and hydrogen bonds effect. The superior collecting power of dimeric collector may be attributed primarily to its special structure and its essential properties.展开更多
A series of piperazine-based Gemini and Bola surfactants were synthesized. Gemini 1 and 5 have well surface activities. Their critical micelle concentrations (cmc) is 6.47×10^-4 mol/L and 1.17×10^-3mol/L, ...A series of piperazine-based Gemini and Bola surfactants were synthesized. Gemini 1 and 5 have well surface activities. Their critical micelle concentrations (cmc) is 6.47×10^-4 mol/L and 1.17×10^-3mol/L, respectively. Bola surfactants 2 and compound 3, possessing better water solubility, have lower surface activities. Calculation, carried out by MM2 energy minimization, showed that compound with more hydrophobic chains in a spacer of limited length is difficult to be synthesized.展开更多
The synthesis and surface activity of gemini surfactants with ester bond as spacer are described. Their critical micelle concentrations (CMC) are much lower than that of conventional surfactants, i.e., 1.62×10^...The synthesis and surface activity of gemini surfactants with ester bond as spacer are described. Their critical micelle concentrations (CMC) are much lower than that of conventional surfactants, i.e., 1.62×10^-5, 1.38×10^-5, 1.28×10^-5 mol·L^-1 for gemini Ⅰ, Ⅱ and Ⅲ respectively. Surface tension at the CMC of gemini Ⅰ, Ⅱ and Ⅲ were 36.4, 38.5, 41.2 mN · m^-1. The physico-chemical properties such as Krafft points, foaming abilities and emulsifying power were also investigated. It is found that the title compounds have low Krafft points and show good solubility in water. The gemini surfactants synthesized also exhibit good foaming properties and excellent emulsifying power toward toluene. The foaming abilities and emulsifying power increase with the increase in carbon number of hydrophobic chain, and this might be caused by the sheer viscosity of different gemini surfactant solution.展开更多
The properties of aqueous two-phase system (ATPS) of mixed solution containing gemini cationic surfactant trimethylene-l,3-bis(dodecyldimethyl ammonium) bromide (12-3-12, 2Br-) and traditional anionic surfactant sodiu...The properties of aqueous two-phase system (ATPS) of mixed solution containing gemini cationic surfactant trimethylene-l,3-bis(dodecyldimethyl ammonium) bromide (12-3-12, 2Br-) and traditional anionic surfactant sodium dodecyl sulfate (SDS) with or without added salt have been studied. An ATPS is formed in a narrow region of the ternary phase diagram different from that of traditional aqueous cationic-anionic surfactant systems. In ATPS region, the lowest total concentration of surfactants varies with the mixing ratio of geminis to SDS. Photographs obtained from freeze-etching, negative-staining and transmission electron microscopy show that the microstructures of two phases are different from each other. Micelles and vesicles can coexist in a single phase. The addition of salts can change the phase diagram of ATPS. Furthermore, the added salts promote the aggregation of rod-like micelles to form coarse network structure that increase the viscosity of solutions. The negative ions of the added salts are the determining factor.展开更多
A novel cardanol sulfonate Gemini surfactant with high surface properties was synthesized by cashew phenol, 1,3-dibromopropane and chlorosulfonic acid through three steps procedure of etherification, sulfonation and n...A novel cardanol sulfonate Gemini surfactant with high surface properties was synthesized by cashew phenol, 1,3-dibromopropane and chlorosulfonic acid through three steps procedure of etherification, sulfonation and neutralization. A surface tension method was employed to investigate the thermo-dynamic properties of micellization in aqueous solution for cardanol sulfonate Gemini surfactant synthesized in laboratory. As a result, the micellization of cardanol sulfonate Gemini surfactant in aqueous solutions is spontaneous and entropy-driven. The micellization process is enthalpy-entropy compensated with the compensation temperature (Tc) of 308 ± 1 K.展开更多
The promotion effect of cationic gemini surfactants for the hydroformylation of 1-dodecene in the organic/aqueous biphasic catalytic system is reported. The hydroformylation reaction in the presence of gemini surfacta...The promotion effect of cationic gemini surfactants for the hydroformylation of 1-dodecene in the organic/aqueous biphasic catalytic system is reported. The hydroformylation reaction in the presence of gemini surfactant occurred with higher turnover frequency and higher selectivity for linear aldehyde than using conventional monomeric surfactant CTAB.展开更多
A new surfactant of Gemini-type,N,N'-((phthylbis(oxy))bis(ethane-2,1-diyl))bis(N,N-dimethyldodecan-1-aminium bromide)is prepped&confirmed.The dissolution suppression impact of the new compound on steel is perf...A new surfactant of Gemini-type,N,N'-((phthylbis(oxy))bis(ethane-2,1-diyl))bis(N,N-dimethyldodecan-1-aminium bromide)is prepped&confirmed.The dissolution suppression impact of the new compound on steel is performed in 1 mol·L^(-1)HCl environment by means of chemical and electrochemical methods.The prepared surfactant is an agreeable dissolution inhibitor for steel.The mitigation efficacy rises with the quantity of the compound.The surfactant belongs to inhibitors of mixed-type.The adsorption of the synthesized compound followed the Langmuir's model.The negative magnitudes of bothΔG_(ads)^(θ) andΔH^(adsθ)indicate that the adsorption process proceeds from its own accord and exothermic.The mechanism of adsorption is elucidated by scanning microscopy.It is established that the transfer resistance(R_(ct))value rose,where the value of the phase element(CPE)reduced with the amount of synthesized inhibitor.According to the experimental data arrived by surface tension measurements,the prepared compound is a powerful active agent at the air/water boundary.展开更多
Experimental data are presented on the enhanced solubilities of fluorene (FLR) resulting from solubilization in aqueous solutions of two conventional surfactants: cationic cetyltrimethylammonium bromide (CTAB) , anion...Experimental data are presented on the enhanced solubilities of fluorene (FLR) resulting from solubilization in aqueous solutions of two conventional surfactants: cationic cetyltrimethylammonium bromide (CTAB) , anionic sodium dodecyl sulfate (SDS), nonioinic polyethylene glycol dodecyl ether (Brij35) and a cationic gemini bis (hexadecyldimethylammonium) pentane dibromide (G5). The critical micellar concentration of surfactants was determined by surface tension measurements and aqueous solubilities of fluorene compound in surfactant solutions were measured spectrophotometrically. Solubilization of PAH compound commenced at the surfactant critical micelle concentration and was proportional to the concentration of surfactant in micelle. The results of the mixed systems were analyzed with the help of regular solution theory, in which the deviation of CMCexp values for mixed surfactant systems from CMCideal was measured by evaluating the interaction parameter, βm. Negative values of βm were observed in all equimolar binary systems which show synergism in the mixed micelle. Attraction force between two oppositely charged head groups lead the strongest synergism effect between cationic gemini and anionic conventional surfactant. In addition to molar solubilization ratio (MSR) solubilization efficiency is also quantified in terms of micelle-water partition coefficient (Km).展开更多
A series of N-acetylated cationic gemini surfactants (3a-e) having dimeric structures derived from tertiary amines were synthesized. Their antifungal potency and surface properties were determined. It also studied the...A series of N-acetylated cationic gemini surfactants (3a-e) having dimeric structures derived from tertiary amines were synthesized. Their antifungal potency and surface properties were determined. It also studied the acute toxicity of the molecule with the best performance and the best water solubility (3e) through Chlorella vulgaris and Daphnia magna bioassays. The results were compared to those obtained for a commercially available reference compound 2-(thiocyanomethylthio) benzothiazole (TCMTB). Parameters such as surface tension (ϒCMC), critical micelle concentration (CMC), surface excess concentration (Γ), and area per molecule (A) were determined. The resulting values indicated that the five gemini surfactants are characterized by good surface-active and self-aggregation properties. All surfactants were tested to evaluate their antifungal activity. Six fungal strains were used to conduct the study. The minimum inhibitory concentration (MIC) value was measured by the fungal growth inhibition. The results of the MICs were compared with two commercially available reference compounds (Fluconazole and TCMTB). The least active molecule was 3e, but 3b and 3d were found to be the most potent compounds with a similar activity for all strains. Candida albicans was the most sensitive one. In contrast, Aspergillus niger was resistant. Ecotoxicity of gemini 3e was assessed: the commercial formulation (TCMTB) was between three and four orders of magnitude more toxic than the gemini one for the biological species tested.展开更多
A series of novel catalysts was developed using cationic Gemini surfactants intercalated in natural montmorillonite (MMT) clay. These Gemini surfactant-MMT intercalates were used to study the kinetics of a nucleophili...A series of novel catalysts was developed using cationic Gemini surfactants intercalated in natural montmorillonite (MMT) clay. These Gemini surfactant-MMT intercalates were used to study the kinetics of a nucleophilic displacement reactions converting n-butyl bromide to n-butyl chloride in a triphase catalytic (TC) system. Most reaction rates compared favorably to those of biphase catalytic reactions where Gemini surfactants were used in the absence of MMT. Catalytic activity varied with Gemini surfactant structure, specifically with carbon spacer group and side chain length. In addition to the ease of catalyst separation that a triphase system affords, Gemini-MMT catalysts are stable and can be recycled and re-used several times.展开更多
基金supported by the National Natural Science Foundation of China(U2001217,22261160370 and 21972006)Guangdong-Hong Kong-Macao Joint Innovation Foundation(2021A0505110003)+1 种基金Shenzhen Basic Research(JCYJ20220818101018038 and JCYJ20200109110628172)Guangdong Province Regional Joint Innovation Foundation(2020B1515120039)。
文摘Carbon-based perovskite solar cells show great potential owing to their low-cost production and superior stability in ambient air.However,scaling up to high-efficiency carbon-based solar modules hinges on reliable deposition of uniform defect-free perovskite films over large areas,which is an unsettled but urgent issue.In this work,a long-chain gemini surfactant is introduced into perovskite precursor ink to enforce self-assembly into a network structure,considerably enhancing the coverage and smoothness of the perovskite films.The long gemini surfactant plays a distinctively synergistic role in perovskite film construction,crystallization kinetics modulation and defect passivation,leading to a certified record power conversion efficiency of 15.46%with Voc of 1.13 V and Jsc of 22.92 mA cm^(-2)for this type of modules.Importantly,all of the functional layers of the module are printed through a simple and high-speed(300 cm min^(-1))blade coating strategy in ambient atmosphere.These results mark a significant step toward the commercialization of all-printable carbon-based perovskite solar modules.
基金We are grateful for the financial support from the National Natural Science Foundation of China(29971001,20031010)the Naturai Science Foundation of Anhui Province(0045115)the Science Foundation for Excellent Young Teachers of Universities of Anhui Province(01080309).
文摘The synthesis and surfactant activities of two new cationic gemini surfactants containing triazole compound as spacer were described. Their critical micelle concentrations (CMC), which are 1.8×10-4 mol/L and 3.9×10-4 mol/L respectively, are much lower than that of conventional surfactant cetyltrimethyl ammonium chloride (CTAC). In addition, compared with some gemini surfactants containing phenylene, xylylene and stilbenyl as spacer, this new kind of surfactants has good solubility in water at room temperature because of containing more hydrophilic groups or atoms in molecules.
文摘Four gemini cationic surfactants {N,N′-di[2-(lauryldimethylamino)acetyl]polymethylenediamine dichloride, LAA-s-LAA, s=2,3,4,6} were synthesized by using four bis(α-chloroacetamide)s and N,N-dimethyllaurylamine, respectively. The molecular structures were characterized by means of IR, ~ 1H NMR, \{~ ~13 C NMR\} and MS, and the behavior of their aqueous solutions was studied. The critical micell concentrations(CMC) of LAA-s-LAA were one order of magnitude lower than that of dodecyltrimethyl ammonium chloride(DTAC). With the change of the length of spacer chain(s), their CMC values change, and CMC reaches the top value at s=4.
基金Supported by the National Natural Science Foundation of China (No.20476025), the Doctoral Research Foundation of the Ministry of Education of China (No.20050251004), E-institute of Shanghai High Institution Grid (No.200303) and Shanghai Municipal Science and Technology Commission of China (No.05DJ14002).
文摘Interaction of anionic polyelectrolyte with cationic gemini surfactant has been investigated by coarse-grained molecular dynamics simulation.Polyelectrolyte facilitates the oppositely charged ionic surfactants to aggregate by suppressing the electrostatic repulsion between ionic head groups leading to the formation of micellar complex.With addition of surfactant,the conformation of polyion chain changes from stretched to random coiled to spherical,and at the same time more free micelles are formed by surfactants in mixtures.Increasing the length of spacer or tail chain in gemini surfactant will weaken its interaction with polyelectrolyte and simultaneously strengthen its tendency to self-assemble.The simulation results are consistent with experimental observations and reveal that the electrostatic interaction plays an important role in the interaction of polyelectrolyte with gemini sur- factant.
基金Project(2005CB623701) supported by the National Basic Research Program of ChinaProject(50874118) supported by the National Natural Science Foundation of ChinaProjet(2007B52) supported by the Foundation for the Author of National Excellent Doctoral Dissertation of China
文摘To search a novel class of effective silicate mineral collectors,the Gemini quaternary ammonium salt surfactant(butane-α,ω-bis(dimethyl dodeculammonium bromide),12-4-12) and its corresponding conventional monomeric surfactant(dedecyl trimethyl ammonium bromide,DTAB) were adopted to comparatively study the flotation behaviors of illite,pyrophyllite and kaolinite. Three silicate minerals with the Gemini surfactant as collector reveal floatability far better than with the corresponding traditional one. At pH 6,the best recoveries of illite,pyrophyllite and kaolinite with 3.5×10-4 mol/L 12-4-12 are 99.2%,91.7% and 99.6%,respectively. The fluorescence and contact angle measurement were also conducted for the further investigation of surfactants aggregation behavior and silicate mineral surface hydrophobic properties. FTIR spectra analysis and electrokinetic analysis show that the mechanism of adsorption of collector molecules on mineral surfaces is almost identical for the electronic attraction and hydrogen bonds effect. The superior collecting power of dimeric collector may be attributed primarily to its special structure and its essential properties.
文摘A series of piperazine-based Gemini and Bola surfactants were synthesized. Gemini 1 and 5 have well surface activities. Their critical micelle concentrations (cmc) is 6.47×10^-4 mol/L and 1.17×10^-3mol/L, respectively. Bola surfactants 2 and compound 3, possessing better water solubility, have lower surface activities. Calculation, carried out by MM2 energy minimization, showed that compound with more hydrophobic chains in a spacer of limited length is difficult to be synthesized.
基金Supported by the National Natural Science Foundation of China (20706013, 20736002), Program for Changjiang Scholars and Innovative Research Team in University (IRT0721), the 111 Project (B08021) and National University of Singapore.
文摘有 cationic 双子座表面活化剂 trimethylene-1,3-bis (dodecyl dimethyl 铵溴化物)(12-3-12 ) 和 anionic 表面活化剂钠 dodecyl 硫酸盐(SDS ) 的 DNA 的相互作用混合了系统被测量荧光,希腊语的第六个字母潜力,紫外力的光谱,和圆形的二色性调查了。当 SDS 不在时,由于静电、恐水病的相互作用, 12-3-12 大批在 micellization 前在 DNA 链上形成象 micelle 一样结构阶段。为 12-3-12 和 SDS 的混合系统, SDS 上的否定费用能对 DNA 竞争因为在相对地控告的表面活化剂之间的更强壮的相互作用,与 cationic 绑 12-3-12,并且这样, catanionic 混合微粒在 DNA/12-3-12 建筑群的形成前被形成。此后,混合微粒上的正电荷与 DNA 绑,并且这样,希腊语的第六个字母潜力从的变化对否定积极没有 SDS,与系统显然不同。同时, SDS 的存在从 DNA/EB 建筑群推迟 ethidium 溴化物(EB ) 的排除。DNA 的符合构造与 12-3-12 过程作为有约束力从本国的 B 形式经历一个变化到 chiral 阶段。在把 SDS 加到 DNA/12-3-12 复杂答案之上,然而, DNA 被释放到体积,阶段再回到 B 形式。
基金the Natural Science Foundation of Hubei Province, China (2000J023)
文摘The synthesis and surface activity of gemini surfactants with ester bond as spacer are described. Their critical micelle concentrations (CMC) are much lower than that of conventional surfactants, i.e., 1.62×10^-5, 1.38×10^-5, 1.28×10^-5 mol·L^-1 for gemini Ⅰ, Ⅱ and Ⅲ respectively. Surface tension at the CMC of gemini Ⅰ, Ⅱ and Ⅲ were 36.4, 38.5, 41.2 mN · m^-1. The physico-chemical properties such as Krafft points, foaming abilities and emulsifying power were also investigated. It is found that the title compounds have low Krafft points and show good solubility in water. The gemini surfactants synthesized also exhibit good foaming properties and excellent emulsifying power toward toluene. The foaming abilities and emulsifying power increase with the increase in carbon number of hydrophobic chain, and this might be caused by the sheer viscosity of different gemini surfactant solution.
基金the National Natural Science Foundation of China (No. 20025618, No. 20236010) Shanghai Municipal Education Commission of China.
文摘The properties of aqueous two-phase system (ATPS) of mixed solution containing gemini cationic surfactant trimethylene-l,3-bis(dodecyldimethyl ammonium) bromide (12-3-12, 2Br-) and traditional anionic surfactant sodium dodecyl sulfate (SDS) with or without added salt have been studied. An ATPS is formed in a narrow region of the ternary phase diagram different from that of traditional aqueous cationic-anionic surfactant systems. In ATPS region, the lowest total concentration of surfactants varies with the mixing ratio of geminis to SDS. Photographs obtained from freeze-etching, negative-staining and transmission electron microscopy show that the microstructures of two phases are different from each other. Micelles and vesicles can coexist in a single phase. The addition of salts can change the phase diagram of ATPS. Furthermore, the added salts promote the aggregation of rod-like micelles to form coarse network structure that increase the viscosity of solutions. The negative ions of the added salts are the determining factor.
文摘A novel cardanol sulfonate Gemini surfactant with high surface properties was synthesized by cashew phenol, 1,3-dibromopropane and chlorosulfonic acid through three steps procedure of etherification, sulfonation and neutralization. A surface tension method was employed to investigate the thermo-dynamic properties of micellization in aqueous solution for cardanol sulfonate Gemini surfactant synthesized in laboratory. As a result, the micellization of cardanol sulfonate Gemini surfactant in aqueous solutions is spontaneous and entropy-driven. The micellization process is enthalpy-entropy compensated with the compensation temperature (Tc) of 308 ± 1 K.
文摘The promotion effect of cationic gemini surfactants for the hydroformylation of 1-dodecene in the organic/aqueous biphasic catalytic system is reported. The hydroformylation reaction in the presence of gemini surfactant occurred with higher turnover frequency and higher selectivity for linear aldehyde than using conventional monomeric surfactant CTAB.
基金The authors gratefully acknowledge financial support from Key Technologies R&D Program Foundation of China(02BA312B07)the National Natural Science Foundation of China(No.20303011)Natural Science Foundation of Shandong Province(Y 2001 B08).
文摘A new surfactant of Gemini-type,N,N'-((phthylbis(oxy))bis(ethane-2,1-diyl))bis(N,N-dimethyldodecan-1-aminium bromide)is prepped&confirmed.The dissolution suppression impact of the new compound on steel is performed in 1 mol·L^(-1)HCl environment by means of chemical and electrochemical methods.The prepared surfactant is an agreeable dissolution inhibitor for steel.The mitigation efficacy rises with the quantity of the compound.The surfactant belongs to inhibitors of mixed-type.The adsorption of the synthesized compound followed the Langmuir's model.The negative magnitudes of bothΔG_(ads)^(θ) andΔH^(adsθ)indicate that the adsorption process proceeds from its own accord and exothermic.The mechanism of adsorption is elucidated by scanning microscopy.It is established that the transfer resistance(R_(ct))value rose,where the value of the phase element(CPE)reduced with the amount of synthesized inhibitor.According to the experimental data arrived by surface tension measurements,the prepared compound is a powerful active agent at the air/water boundary.
文摘Experimental data are presented on the enhanced solubilities of fluorene (FLR) resulting from solubilization in aqueous solutions of two conventional surfactants: cationic cetyltrimethylammonium bromide (CTAB) , anionic sodium dodecyl sulfate (SDS), nonioinic polyethylene glycol dodecyl ether (Brij35) and a cationic gemini bis (hexadecyldimethylammonium) pentane dibromide (G5). The critical micellar concentration of surfactants was determined by surface tension measurements and aqueous solubilities of fluorene compound in surfactant solutions were measured spectrophotometrically. Solubilization of PAH compound commenced at the surfactant critical micelle concentration and was proportional to the concentration of surfactant in micelle. The results of the mixed systems were analyzed with the help of regular solution theory, in which the deviation of CMCexp values for mixed surfactant systems from CMCideal was measured by evaluating the interaction parameter, βm. Negative values of βm were observed in all equimolar binary systems which show synergism in the mixed micelle. Attraction force between two oppositely charged head groups lead the strongest synergism effect between cationic gemini and anionic conventional surfactant. In addition to molar solubilization ratio (MSR) solubilization efficiency is also quantified in terms of micelle-water partition coefficient (Km).
文摘A series of N-acetylated cationic gemini surfactants (3a-e) having dimeric structures derived from tertiary amines were synthesized. Their antifungal potency and surface properties were determined. It also studied the acute toxicity of the molecule with the best performance and the best water solubility (3e) through Chlorella vulgaris and Daphnia magna bioassays. The results were compared to those obtained for a commercially available reference compound 2-(thiocyanomethylthio) benzothiazole (TCMTB). Parameters such as surface tension (ϒCMC), critical micelle concentration (CMC), surface excess concentration (Γ), and area per molecule (A) were determined. The resulting values indicated that the five gemini surfactants are characterized by good surface-active and self-aggregation properties. All surfactants were tested to evaluate their antifungal activity. Six fungal strains were used to conduct the study. The minimum inhibitory concentration (MIC) value was measured by the fungal growth inhibition. The results of the MICs were compared with two commercially available reference compounds (Fluconazole and TCMTB). The least active molecule was 3e, but 3b and 3d were found to be the most potent compounds with a similar activity for all strains. Candida albicans was the most sensitive one. In contrast, Aspergillus niger was resistant. Ecotoxicity of gemini 3e was assessed: the commercial formulation (TCMTB) was between three and four orders of magnitude more toxic than the gemini one for the biological species tested.
文摘A series of novel catalysts was developed using cationic Gemini surfactants intercalated in natural montmorillonite (MMT) clay. These Gemini surfactant-MMT intercalates were used to study the kinetics of a nucleophilic displacement reactions converting n-butyl bromide to n-butyl chloride in a triphase catalytic (TC) system. Most reaction rates compared favorably to those of biphase catalytic reactions where Gemini surfactants were used in the absence of MMT. Catalytic activity varied with Gemini surfactant structure, specifically with carbon spacer group and side chain length. In addition to the ease of catalyst separation that a triphase system affords, Gemini-MMT catalysts are stable and can be recycled and re-used several times.