Cationic Gemini Surfactants with Oligo(oxyethylene) Spacer Groups and Their Use in the Polymerization of Styrene in Ternary Microemulsion

Abstract

The aggregation and phase behavior, micelle and microemulsion structure, and the polymerization behavior of various binary and ternary systems containing water, (oligooxa)alkanediyl-α,ω-bis(dimethyldodecylammonium bromide) surfactants (12-EO x -12), and styrene are reported. The hydrophilic spacer chain length x in the cationic gemini surfactants was varied between 0 and 5. With increasing spacer chain length the surface area per molecule at the air−water interface increases, whereas the single-phase region of the ternary microemulsion systems is largest for x being 1 and decreases with increasing x in the investigated concentration range. Small-angle neutron scattering (SANS) and cryogenic temperature transmission electron microscopy (cryo-TEM) measurements indicate that the micelle and microdroplet dimensions decrease with increasing x. Polymerization was carried out at 25 and 60 °C using 60Co γ-rays. Spherical polystyrene particles in the nanometer size range were obtained, the particle size being dependent on the spacer length of the gemini surfactants and on the polymerization temperature. At 25 °C, particle size and molecular weight of polystyrene were maximum at medium spacer length, while at 60 °C, the particle size decreased with increasing x, in correspondence to the microstructural properties of the microemulsions observed by SANS. The experimental results suggest that the chemical structure of the surfactant molecules used in the microemulsion formulation has a strong influence on the particle properties after polymerization. This influence depends on the curvature of the interfacial film induced by the surfactant molecules.

Dimeric (Gemini) Surfactants: Effect of the Spacer Group on the Association Behavior in Aqueous Solution

“…A2 : R 1 = R 2 = C m H 2m+1 ; Y = CHOH, (CHOH) 2 ; x = y = 1 (14). A3: R 1 = R 2 = C m H 2m+1 ; Y = (OCH 2 CH 2 ) z , x = 2; y = 0; m-EO z -m surfactants (15). A4: R 1 = R 2 = C m H 2m+1 ; Y = C ≡ C; x = y = 1 (16).…”

“…The reported a values were calculated on the basis of n = 2 (13,(23)(24)(25), on the assumption that one of the two charged groups is neutralized by a bound counterion, or n = 3, on the assumption of a full dissociation of the dimeric surfactants (16,17,(26)(27)(28)(29). Some studies reported two sets of values of a based on n = 2 and 3 (15,30). The same problem arises for ionic trimeric surfactants for which the value n = 4 should be used if the surfactant is fully ionized at C < cmc.…”

Urea-based gemini surfactants: Synthesis, aggregation behaviour and biological activity

“…Gemini surfactants can also serve as structural units in the formulation of cationic liposomes [23]. As for industrial applications, gemini surfactants show inhibitive effect on iron corrosion [24], act as efficient agents in oil recovery [25], styrene polymerisation [26,27], dying of textiles [28,29]. They appeared to be good stabilisers of polymer latex particles [30], separation agents in capillary chromatography [31], gelators of organic solvents [32], and reactants in the synthesis of silica mesophases [33].…”

Microcalorimetric Study of the Catalytic Properties of SBA-15 Modified with Cu or Fe for Adsorption/oxidation of Methyl mercaptane

“…The extent of irreversible reaction decreased gradually with subsequent pulses and the corresponding heat release also showed this decreasing trend up to the seventh pulse. The amount of methyl mercapthane adsorbed per gram of the catalyst up to this stage roughly corresponded to the sites with acidic character in the catalysts [47][48][49][50] . Starting from the ninth pulse each adsorption event was followed by desorption of reversibly adsorbed methyl mercapthan and corresponding endothermic peaks were seen in the adsorption microcalorimetry thermal curves.…”