Synthesis and surface-active properties of a series of new anionic gemini compounds

Comparative studies on the aggregate formation of synthesized zwitterionic gemini and monomeric surfactants in the presence of the amphiphilic antipsychotic drug chlorpromazine hydrochloride in aqueous solution: an experimental and theoretical approach

The formation of aggregates, which are widely used in the field of biochemistry and the medical industry, was studied with different compositions of alkyl betaine gemini surfactant (C14Ab) in conjugation with chlorpromazine hydrochloride (CPZ). The results were compared with those of a single-chain zwitterionic surfactant (C12DmCB) of the same type with CPZ. Dynamic light scattering (DLS), confocal laser scanning microscopy (CLSM), and transmission electron microscopy (TEM) methods were used to distinguish the aggregates for the CPZ/C14Ab system in aqueous solutions above a certain mole fraction of the drug CPZ (αCPZ = 0.2). Time-resolved fluorescence decay measurements of acridine orange revealed relative polarity near the head group regions of mixed micelle (CPZ/C14Ab and CPZ/C12DmCB) systems. The hydrophilic environment around the head group regions of the CPZ/C14Ab system was different from that in the case of the CPZ/C12DmCB system. On the other hand, several theoretical models were employed (Clint, Rubingh, Motomura, and SPB) for mixed micellar systems to elucidate the different interaction parameters. Such a systematic study of a zwitterionic gemini amphiphile and its interaction with other amphiphiles and an amphiphilic drug molecule is rare in the literature.

Synthesis and Properties of Sugar-Based Gemini Surfactants

A series of new gemini surfactants having hydrophilic glucosides were synthesized from glucose via two different synthesis roads, including N,N′-didodecyl-N,N′-bis-(1-glucosyl-2-hydroxyl-propyl)-p-phthaloyl amide [B(DG)PA], N,N′-didodecyl-N,N′-bis(1-glucosyl-2-hydroxyl-propyl)-2,5-dicarboxylate p-phthaloyl amide [B(DGC)PA], N,N′-didodecanoyl-N,N′-bis-(1-glucosyl-2-hydroxyl-propyl) ethylenediamine [B(DG)EA], and N,N′-didodecanoyl-N,N′-bis-(1-glucosyl-2-hydroxyl-propyl) hexanediamine [B(DG)HA]. The final products were characterized by IR and NMR spectral measurements and by interfacial tension measurements. The critical micellar concentrations (cmc) of these gemini surfactants were determined to be 2.49 × 10−6, 1.93 × 10−6, 2.47 × 10−6 and 1.66 × 10−6 mol L−1, respectively, which are about one order of magnitude lower than the corresponding monomeric surfactants (GHPDA). The results showed that these synthesized sugar-based gemini surfactants had high abilities to reduce the surface or oil-water interface tension. The high surface activity of these synthesized molecules was attributed to their unique structure where two optimally spaced hydrophobic chains and hydrophilic groups were present.

Surface, interfacial and aggregation properties of sulfonic acid-containing gemini surfactants with different spacer lengths

Four sulfonic acid-containing gemini surfactants 9BA-m-9BA (m=2, 3, 4, 6), 6,6'-(ethane-1,2-diylbis(oxy)) bis(3-nonylbenzenesulfonic acid) (9BA-2-9BA), 6,6'-(propane-1,3-diylbis(oxy)) bis(3-nonylbenzenesulfonic acid) (9BA-3-9BA), 6,6'-(butane-1,4-diylbis(oxy)) bis(3-nonylbenzenesulfonic acid) (9BA-4-9BA), and 6,6'-(hexane-1,6-diylbis(oxy)) bis(3-nonylbenzenesulfonic acid) (9BA-6-9BA), were synthesized and characterized by Fourier transform infrared (FTIR), (1)H NMR, elemental analysis, and melting temperature measurements. Their ability to lower the water surface tension and hexadecane/water interfacial tension was measured and correlated with the hydrophobicity and length of their alkyl spacer chain. Their aggregates in aqueous solutions were investigated using dynamic light scattering and transmission electron microscopy. Spherical vesicles could be found in aqueous solutions of four gemini surfactants with an apparent hydrodynamic radius (Rh) of approximately 100 nm. The critical micelle concentration (cmc) of four gemini surfactants evaluated by surface tension measurements was 1 order of magnitude smaller than that of conventional single-chain surfactant sodium dodecylsulfonate (SDS). And their C20, the gemini surfactant concentration required for lowering the surface tension of water by 20 mN/m, was about 2 orders of magnitude smaller than that of SDS, showing excellent efficiency at reducing the surface tension of water. In addition, the hexadecane/water interfacial tension could be less than 1.0 mN/m after using pure 9BA-m-9BA in water. Using 9BA-6-9BA the hexadecane/water interfacial tension was reduced to 0.21 mN/m.

Interactions between gemini surfactants and polymers: thermodynamic studies

Aqueous mixtures containing a homopolymer, poly(vinylpyrrolidone) (PVP), or a hydrophobically modified graft copolymer, HM-pullulan, (PULAU9, where 9 stands for the nominal substitution degree), and different Gemini surfactants have been investigated at 25.0 degrees C. A wide variety of experimental conditions were addressed by changing the amount of polymer and of surfactant. The Gemini surfactants were synthesized, purified, and characterized by routine methods. They differ from each other in polar head groups (two sulfonate-, two quaternary ammonium-, or two arginine-based groups), in alkyl chain length (11 or 12 carbon atoms), and in the distance between the polar head groups. The spacers consist of 2, 3, and 6 methylene units or 3 oxyethylene units. Surface activity and solution calorimetry measurements yield some physicochemical features inherent to micelle formation and polymer-surfactant interactions. The data are supported by ionic conductivity, detecting the critical thresholds and quantifying the modifications in binding associated with critical association (CAC) and micelle formation (CMC*). The Gibbs energy of transfer from the micelles to a polymer-binding site, DeltaGtrans, was evaluated from the CAC/CMC* ratios versus the amount of added polymer. A similar procedure determined the enthalpy of transfer, DeltaHtrans. DeltaGtrans decreases with added polymer, whereas DeltaHtrans becomes more negative on increasing the amount of polymer in the medium. According to the selected data presented here, cationic Geminis do not interact with PVP, while significant interactions have been observed in other surfactants. In mixtures with PULAU9, the interaction is significant for all Geminis. This effect is due to interactions between the surfactants and the hydrophobic alkyl groups on the main polymer chain. The pendent groups facing away from the polysaccharide chain act as binding sites for aggregates onto such polymers.

Effect of hydrocarbon parts of the polar headgroup on surfactant aggregates in gemini and bola surfactant solutions

Cationic gemini surfactant homologues alkanediyl-alpha,omega-bis(dodecyldiethylammonium) bromide, [C12H25(CH3CH2)2N(CH2)SN(CH2CH3)2C12H25]Br2, where S = 4, 6, 8, 10, or 12, referred to as C12CSC12(Et), and cationic bolaamphiphiles BPHEAB (biphenyl-4,4'-bis(oxyhexamethylenetriethylammonium) bromide), PHEAB (phenyl-4,4'- bis(oxyhexamethylenetriethylammonium) bromide) were synthesized, and their aggregation behaviors in aqueous solution were studied and compared by means of dynamic light scattering, fluorescence entrapment, and transmission electron microscopy. Spherical vesicles were found in the aqueous solutions of these gemini and bola surfactants, which can be attributed to the increase of the hydrocarbon parts of the polar headgroup of the surfactants. In combination with the result of the other gemini with headgroup of propyl group, the increase of the hydrophobic parts of the surfactant polar headgroup will be beneficial to enhance the aggregation capability of the gemini and bola surfactants. Both of the vesicles formed in the gemini and bola systems showed good stabilities with time and temperature, but different stability with salt due to the different membrane conformations of surfactant molecules in the vesicles.

Metathesis depolymerization for removable surfactant templates

Current methodologies for the production of meso- and nanoporous materials include the use of a surfactant to produce a self-assembled template around which the material is formed. However, post-production surfactant removal often requires centrifugation, calcination, and/or solvent washing which can damage the initially formed material architecture(s). Surfactants that can be disassembled into easily removable fragments following material preparation would minimize processing damage to the material structure, facilitating formation of templated hybrid architectures. Herein, we describe the design and synthesis of novel cationic and anionic surfactants with regularly spaced unsaturation in their hydrophobic hydrocarbon tails and the first application of ring closing metathesis depolymerization to surfactant degradation resulting in the mild, facile decomposition of these new compounds to produce relatively volatile nonsurface active remnants.

Thermally cleavable surfactants based on furan-maleimide Diels-Alder adducts

Two new surfactant molecules are reported that contain thermally labile Diels-Alder adducts connecting the hydrophilic and hydrophobic sections of each molecule. The two surfactants possess identical hydrophobic dodecyl tail segments but have phenol and carboxylic acid hydrophilic headgroups, respectively. Deprotonation with potassium hydroxide affords the formation of water-soluble surfactants. Room temperature aqueous solutions of both surfactants exhibit classical surface-active agent behavior similar to common analagous alkylaryl surfactant molecules. Critical micelle concentrations have been determined for each surfactant through dynamic surface tension and dye solubilization techniques. Small-angle neutron scattering measurements of the aqueous surfactant solutions indicate the presence of spherical micelles with radii of 16.5 angstroms for the carboxylate and 18.8 angstroms for the phenolate. When these surfactants are exposed to elevated temperatures (>50 degrees C), the retro Diels-Alder reaction occurs, yielding hydrophilic and hydrophobic fragments. Aqueous solutions of each surfactant subsequently exhibit a loss of all surface-active behavior and the micellar aggregates are no longer detectable.

Dimeric and oligomeric surfactants. Behavior at interfaces and in aqueous solution: a review

Dimeric and oligomeric surfactants are novel surfactants that are presently attracting considerable interest in the academic and industrial communities working on surfactants. This paper first presents a number of chemical structures that have been reported for ionic, amphoteric and nonionic dimeric and oligomeric surfactants. The following aspects of these surfactants are then successively reviewed the state of dimeric and oligomeric surfactants in aqueous solutions at concentration below the critical micellization concentration (cmc); their behavior at the air/solution and solid/solution interfaces; their solubility in water, cmc and thermodynamics of micellization; the properties of the aqueous micelles of dimeric and oligomeric surfactants (ionization degree, size, shape, micropolarity and microviscosity, solution microstructure, solution rheology, micelle dynamics, micellar solubilization, interaction between dimeric surfactants and water-soluble polymers); the mixed micellization of dimeric surfactants with various conventional surfactants; the phase behavior of dimeric surfactants and the applications of these novel surfactants.