Dimethylene Bis Research Articles

Extraction of Bionanomaterials from the Aqueous Bulk by Using Surface Active and Water-Soluble Magnetic Nanoparticles.

Surface active and water-soluble magnetic nanoparticles (NPs) were used to demonstrate the extraction of bionanomaterials from the aqueous bulk. Au NPs conjugated with different water-insoluble and water-soluble proteins were used as model bionanomaterials. UV-visible studies, zeta potential, and microscopic analyses were performed to quantify the extraction. Sodium dodecyl sulfate and dimethylene bis(dodecyldimethylammonium bromide) (12-2-12) stabilized surface active magnetic NPs were fully capable of extracting Au NPs conjugated with predominantly hydrophobic proteins from the aqueous bulk when placed at the aqueous-air interface. However, they were poor in extracting Au NPs from the aqueous bulk which were coated with predominantly hydrophilic water-soluble protein. On the other hand, water-soluble dodecyldimethyl-3-ammonio-1-propanesulfonate stabilized magnetic NPs proved to be fully capable of extracting all kinds of Au NPs conjugated with either water-soluble or water-insoluble proteins. The results highlight the remarkable ability of magnetic NPs in the extraction of bionanomaterials when placed at either biointerfaces or in the aqueous bulk of biological systems.

TG/DSC/FTIR study of porous copolymeric beads based on the dimethacrylate derivative of m-xylene

The present study describes the thermal properties of a series of porous microspheres synthesised from the dimethacrylate derivative of m-xylene, i.e. (4,6-dimethyl-1,3-phenylene)dimethylene bis(2-methylprop-2-enoate) and divinylbenzene via an aqueous suspension polymerisation in the presence of toluene and decan-1-ol as porogenic diluents. Various molar ratios of monomers were applied in the syntheses (1:4, 1:1, 4:1). The TG/DSC/FTIR analyses were performed in inert (helium) and oxidative (synthetic air) atmospheres. They revealed that the properties of the copolymeric microspheres were dependent on both their chemical composition and the testing atmosphere. The microspheres were stable up to 229–296 °C (in helium) and 302–308 °C (in synthetic air), as determined on the basis of the temperature of 1% mass loss. However, the most thermally stable were those synthesised at the molar ratio of the dimethacrylate derivative of m-xylene to divinylbenzene equal to 1:4. In helium, the copolymeric beads decomposed in one, two or three stages, whereas in synthetic air in two ones. The basic decomposition volatiles were carbon monoxide, carbon dioxide and organic carbonyl products, including esters, carboxylic acids and aldehydes as well as unsaturated and aromatic compounds.

Effect of Hydrophobicity and Temperature on the Interactions in the Mixed Micelles of Triblock Polymers [(EO76PO29EO76) and (EO19PO69EO19)] with Monomeric and Gemini Surfactants

AbstractThe interactions in the mixed micelles of two triblock polymers, F68 (EO76PO29EO76) and P123 (EO19PO69EO19), with a series of monomeric (dodecyltrimethyl ammonium bromide, tetradecyltrimethyl ammonium bromide and cetyltrimethyl ammonium bromide) and gemini {dimethylene bis(alkyldimethyl ammonium bromide), m‐2‐m, where m = 10, 12 and 14} cationic surfactants were studied by surface tension and viscosity measurements in aqueous solutions at different temperatures. The mixed micellar and interfacial properties of the binary mixtures were analyzed using Clint, Rubingh, Rosen and Maeda approaches. Both F68 and P123 show weak interactions with the studied cationic surfactants at 298.15 K which become favorable (synergistic) at higher temperatures. Further, the synergistic interactions are more in mixtures of P123 than F68 at higher temperatures. A comparison of the effects of number of EO and PO blocks in triblock polymers on various physicochemical parameters of the mixed micelles has also been made. The unfavorable enthalpy changes are compensated by favorable entropy changes as a result of the hydrophobic effect. The relative viscosity (ηr) studies show that the size of the micelles formed by pure P123 is smaller than those of F68. The values of ηr for the mixed micelles of F68 show significant variation with chain length of gemini surfactants whereas no such effect is seen in mixtures with P123.

Influence of Headgroup on the Aggregation and Interactional Behavior of Twin-Tailed Cationic Surfactants with Pluronics

The surface tension measurements have been employed to characterize the micellar and interfacial behavior of pure and mixed systems of twin-tailed cationic surfactants: dimethylene bis(decyldimethylammonium bromide) (10-2-10), didecydimethylammonium bromide (DDAB), and 1,3-didecyl-2-methylimidazolium chloride (DDIC) with pluronics P84 and F108 in the aqueous solution. The interactions of each surfactant with both pluronics are found to be nonideal and synergistic except for the mixed system of 10-2-10 + F108, for which interactions are antagonistic and every interaction has been studied on the basis of headgroup disparity. Dynamic light scattering (DLS), zeta (ζ) potential, and small angle neutron scattering (SANS) measurements have been used to determine the influence of the mixing ratio on the morphology of the various mixed aggregates that are formed. Pure DDAB is found to form unilamellar vesicles whereas pure 10-2-10 and DDIC form prolate ellipsoidal micelles. The unilamellar vesicles of DDAB are destructed to yield spherical mixed micelles on addition of pluronics via expansion or contraction of vesicles. However, the pure pluronics and their mixed systems with 10-2-10 and DDIC form charged spherical micelles, and charge is confirmed by thenfractional charge and ζ values. The ζ values of pure surfactants are found to decrease on addition of pluronics, indicating a decrease in surface charge on inclusion of pluronics.

Mixed Micellar and Interfacial Interactions of a Triblock Polymer (EO37PO56EO37) with a Series of Monomeric and Dimeric Surfactants

AbstractThe mixed micellar and interfacial properties of mixtures of triblock polymer (TBP) with a series of monomeric (dodecyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, and cetyltrimethylammonium bromide, and dimeric (dimethylene bis[alkyldimethylammonium bromide], m‐2‐m, where m = 10, 12, and 14) cationic surfactants were investigated using surface tension and viscosity measurements in aqueous solutions at different temperatures. Various physicochemical properties such as critical micelle concentration, mixed micellar mole fraction, interaction parameter, interfacial, and thermodynamic parameters were evaluated. All the binary mixtures exhibit synergistic interactions which increase with temperature and pass through a minimum with the increase in hydrophobic chain length of the cationic surfactants. The contribution of TBP in mixed micelle formation also increases with the hydrophobic chain length of the surfactants. The interfacial and thermodynamic parameters reveal that the adsorption of the surfactant mixtures at the air–solution interface is more favorable than that of micelle formation and the unfavorable enthalpy changes are overwhelmed by favorable entropy changes. Further, the mixtures of TBP with smaller chain length surfactants show a sharp rise in relative viscosity at higher mole fractions of these surfactants.

Room Temperature Surfactant Assisted Crystal Growth of Silver Nanoparticles to Nanoribbons

This study presents a simple and systematic growth of Ag nanoparticles (NPs) to nanoribbons by changing the hydrophobicity parameter of a series of cationic Gemini surfactants by using seed-mediated approach in aqueous phase at room temperature. At lowest hydrophobicity of a Gemini surfactant (i.e., dimethylene bis(decyldimethyl-ammonium bromide), 10-2-10), Ostwald ripening process was observed which caused fusion among growing Ag NPs. This process was quite prominent when 0.5 ml of Ag seed solution was used for the growth process but weakened as the amount of seed decreased to 0.125 ml. Similar behavior was demonstrated by Au NPs studied for comparison. The nanostructures were characterized by TEM, XRD, and UV-visible measurements. Further increase in the hydrophobicity of a Gemini surfactant from 10-2-10 to dimethylene bis(tetradecyldimethylammonium bromide) (14-2-14) through dimethylene bis(dodecyldimethylammonium bromide) (12-2-12), resulted in the participation of threads like micelles and liquid crystalline phase as soft-templates towards the nanoribbon formation. Fine polycrystalline Ag nanoribbons were obtained in the presence 14-2-14 and were characterized by the HRTEM and EDX analysis.

Vinyl monomers-induced synthesis of polyvinyl alcohol-stabilized selenium nanoparticles

A simple wet chemical method has been developed to synthesize selenium nanoparticles (size 100–200 nm), by reaction of sodium selenosulphate precursor with different vinyl monomers, such as acrylamide, N,N′-dimethylene bis acrylamide, methyl methacrylate, sodium acrylate, etc., in aqueous medium, under ambient conditions. Polyvinyl alcohol has been used to stabilize the selenium nanoparticles. Average size of the synthesized selenium nanoparticles can be controlled by adjusting concentration of both the precursors and the stabilizer. Rate of the reaction as well as size of the resultant selenium nanoparticles have been correlated with the functional groups of the different monomers. UV–vis optical absorption spectroscopy, X-ray diffraction, energy dispersive X-rays, differential scanning calorimetry, atomic force microscopy, scanning electron microscopy and transmission electron microscopy techniques have been employed to characterize the synthesized selenium nanoparticles. Gas chromatographic analysis of the reaction mixture established the non-catalytic role of the vinyl monomers, which were found to be consumed during the course of the reaction.

Aqueous-Phase Room-Temperature Synthesis of Gold Nanoribbons: Soft Template Effect of a Gemini Surfactant

Gold (Au) nanoribbons were synthesized in aqueous phase under ambient conditions by using dimethylene bis(tetradecyldimethyl-ammonium bromide) (14-2-14) as a capping agent as well as a soft template. A two steps seed-growth (S-G) method was used. The first step of S-G method mainly gave nanorods of high aspect ratio along with nanoparticles of other shapes, but the next step produced mainly fine Au nanoribbons of several micrometers long, 50–150 nm wide, and ≈5 nm thick. They were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, energy dispersive X-ray, and X-ray diffraction analysis. Isotropic liquid crystalline phase of 14-2-14 provided a soft template effect and derived nanorods of high aspect ratios toward nanoribbon formation at room temperature.

Topographical and photophysical properties of poly(amidoamine) dendrimers with ionic surfactants

The atomic force microscopy (AFM) and transmission electron microscopy (TEM) have been performed on the poly(amidoamine) dendrimers of second generation (2G) and its fluoroderivative (2D) at room temperature. Both studies have demonstrated that 2G and 2D exist in large aggregates on solid surface. The presence of ionic surfactants facilitates their solubilization in micellar phase resulting in the aggregates of much smaller dimensions. The aqueous bulk properties of 2G and 2D both in the absence as well as in the presence of ionic surfactants (i.e. dodecyltrimethylammonium bromide (DTAB), dimethylene bis (dodecyldimethylammonium bromide) (12-2-12), and sodium dodecyl sulfate (SDS)) have been carried out with the help of pyrene fluorescence and turbidity ( τ) measurements. From the variation of I 1/ I 3 pyrene intensity and the τ of these aqueous solutions, it has been found that both DTAB and 12-2-12 interact with the surface groups of 2G and 2D favorably in basic medium, while SDS has been found to interact with that in acidic medium. Apart from this, interactions of cationic surfactants have been found to be stronger with 2D in comparison to 2G, while reverse has been observed in the case of SDS.

Estimation of degree of counterion binding and thermodynamic parameters of ionic surfactants from cloud point measurements by using triblock polymer as probe

Cloud point ( C P ) was measured for ternary mixtures of different ionic surfactants such as sodium dodecyl sulfate (SDS), dodecyltrimethylammonium bromide (DTAB), and dimethylene bis(dodecyldimethylammonium bromide) (12–2–12) plus triblock polymer (TBP) ((PEO) 2(PPO) 15.5(PEO) 2) plus water, keeping the concentration of TBP constant and varying the surfactant concentration from pre- to postmicellar regions. These experiments were also performed in the presence of different fixed amounts of NaBr to evaluate the salt effect on the clouding behavior of these ternary mixtures. The C P value of TBP exhibits a drastic change at the cmc of each surfactant. The cmc values thus obtained both in the absence and in the presence of NaBr were used to evaluate counterion binding ( β) with the Corrin–Harkins method. β values were also used to evaluate the thermodynamic parameters of these ionic surfactants. The results suggest that the β values evaluated using this method, especially at low [TBP], are in good agreement with those reported in the literature.

Cyclic voltammetry investigation of the mixed micelles of cationic surfactants with pluronic F68 and TritonX-100

The cyclic voltammetry (CV) measurements for the combinations of hexadecyltrimethylammonium bromide (HTAB), tetradecyltrimethylammonium bromide (TTAB), dimethylene bis(tetradecyldimethylammonium bromide) (14-2-14), and dimethylene bis(hexadecyldimethylammonium bromide) (16-2-16) with TritonX-100 (TX-100) and triblock polymer, Pluronic F68, have been carried out in the presence of 0.1 M KCl. The critical micelle concentrations of these binary mixtures over the whole mixing range have been determined by using electroactive probe 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO). A variation in the various micellar parameters and diffusion coefficient of the electroactive probe indicates that the mixed micelle formation between the components of monomeric/dimeric and TX-100/F68 binary mixtures was synergistic in nature. The stronger synergistic interactions were observed for the cationic combinations with F68 rather than TX-100. The results have been discussed on the basis of reduction in the cationic polar head group repulsions by the intercalation of non-ionic surfactants in the mixed micelle.

Antagonistic mixing behavior of cationic gemini surfactants and triblock polymers in mixed micelles

Conductance ( κ ) , pyrene fluorescence ( I 1 / I 3 ) , cloud point ( C P ) , and Krafft temperature ( K T ) measurements have been carried out for various dimethylene bis(alkyldimethylammonium bromide) (gemini) surfactants with different poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) triblock polymers (TBP). From the κ and I 1 / I 3 studies, the critical micelle concentrations of mixed micelle formation between the gemini and TBP have been determined using regular solution theory. It has been observed that mixed micelle formation in all the binary mixtures of gemini + TBP occurs due to the unfavorable mixing, the magnitude of which decreases with increased hydrophobicity of the gemini component. The results are further supported by evaluating the mean micelle aggregation number and enthalpy of fusion from fluorescence and Krafft temperature measurements, respectively.

Fluorescence studies of interactions of ionic surfactants with poly(amidoamine) dendrimers

The pyrene fluorescence measurements have been carried out for the micelle formation of sodium dodecyl sulfate (SDS), dodecyltrimethylammonium bromide (DTAB), and dimethylene bis(dodecyldimethylammonium bromide) (12-2-12) in the presence of fixed different amounts of various generations of poly(amidoamine) (PAMAM). The critical micelle concentration (cmc) of SDS decreases with an increase in the fixed amount of PAMAM, suggesting the facilitation of micellization due to the participation of SDS–PAMAM complex in the micelle formation. This behavior has not been observed for DTAB/12-2-12 in the presence of various generations of PAMAM. The results indicate that SDS always has stronger interactions with all the generations of PAMAM in comparison to those of DTAB and 12-2-12.

Interactions of monomeric and dimeric cationic surfactants with anionic polyelectrolytes: a fluorescence study

The interactions of conventional cationic, i.e. dodecyl-(DTAB), tetradecyl-(TTAB), and hexadecyltrimethylammonium bromides (HTAB), and dimeric cationic surfactants, i.e. dimethylene bis decyl-(10-2-10), and dodecyldimethylammonium bromides (12-2-12) with anionic polyelectrolytes, were studied by fluorescence measurements. The variation of I1/I3 ratio of the fluorescence of pyrene in aqueous solutions of polyelectrolytes was measured as a function of surfactant concentration. A three-step aggregation process involving the critical aggregation concentration (cac) and critical micelle concentration (cmc) was observed in each case. The cationic surfactants with lower hydrophobicity demonstrated higher degree of binding and vice versa.

Association behavior of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) block copolymers with cationic surfactants in aqueous solution.

The association behavior of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) block copolymers in aqueous solution with hexadecyltrimethylammonium bromide (HTAB), tetradecyltrimethylammonium bromide (TTAB), and dimethylene bis(decyldimethylammonium bromide) (10-2-10), was studied by fluorescence, viscosity, and Krafft temperature measurements. It has been observed that (EO)18(PO)31(EO)18 interacts more strongly than (EO)2(PO)15.5(EO)2 and (EO)2.5(PO)31(EO)2.5 with HTAB/TTAB due to synergistic interactions. A stronger capability of (EO)18(PO)31(EO)18 to interact with cationic surfactants arises from the greater number of electronegative EO units (total 36 EO units) than of (EO)2(PO)15.5(EO)2 (total 4 EO units) and (EO)2.5(PO)31(EO)2.5 (total 5 EO units). The antagonistic mixing behavior of present triblock polymers has been observed with 10-2-10. A difference in the mixing behavior of the latter from that of HTAB/TTAB has been attributed to its dimeric nature, which may create steric hindrances with triblock polymer components at the head group region in the mixed state.