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Gold nanoparticles were prepared in the presence of poly(propylene imine)dendrimers (PPI) (generation 2,3, and 4) with surface amino groups by UV-irradiation. UV-vis absorption, dynamic light scattering, and transmission electron microscopy have been used to study the formation and structure of gold-PPI nanocomposites. The reduction of Au 3 + ions proceeded with an increase of UV irradiation time and the average diameters of gold nanoparticles obtained increased with an increase of dendrimer concentration. It is suggested that the structure of gold-PPI nanocomposites is formed by adsorption of PPI dendrimers on the gold nanoparticles. In addition, studies of reduction reaction of 4-nitrophenol by the gold nanoparticles with NaBH 4 show that the rate constants are very similar even for different generations as well as the different concentrations of PPI dendrimers.

A cationic dendrimer-type tetrameric surfactant (C 8 qbG0) with four octyl chains and four ammonium groups was synthesized by the reaction of poly(amidoamine) dendrimers with generation of zero and glycidyldimethyloctylammonium bromide. The physicochemical properties of C 8 qbG0 and of their mixtures with sodium dodecyl sulfate (SDS) were characterized by investigating surface tension, electrical conductivity, fluorescence of pyrene, and dynamic light-scattering. The critical micelle concentration (cmc) of C 8 qbG0 was 13 mmol dm −3 at the concentration of one terminal group and the surface tension at the cmc attained 34 mN m −1 . The occupied area of C 8 qbG0 was 1.94 nm 2 molecule −1 , indicating that the tetrameric dendrimers adsorb widely at the air/water interface. The fluorescence intensity ratio of the first-to-third band in the emission spectra of pyrene for C 8 qbG0 decreased from around the cmc obtained by the surface tension measurement. The hydrodynamic radius of C 8 qbG0 determined by dynamic light-scattering was about 1.3 nm. The addition of SDS to the aqueous solutions of C 8 qbG0 enhanced the surface activities; the mixtures exhibited lower cmc, lower surface tension, and higher solubilization of pyrene than SDS alone. It was found that the mixtures of C 8 qbG0 and SDS form large aggregates due to the interactions between their alkyl chains as well as hydrophilic groups.

Formation of stable gold nanoparticles of different size and shape has been reported via UV photoactivation of HAuCl4 in variable concentrations of TX-100. It has been shown that smaller particles ...

The simultaneous adsorption of poly( 1-vinylpyrrolidone-co-acrylic acid) (PVcA) and sodium dodecyl sulfate (SDS) on positively charged alumina particles is carried out at pH 5.2 by measuring the amount of PVcA and SDS adsorbed, ζ potential, and sedimentation rate of alumina suspensions. In addition, conformation of PVcA and SDS adsorbed using their corresponding spin-labeled ones is estimated. The amount of PVcA adsorbed increases sharply and becomes a plateau with an increase of PVcA concentration, while a typical adsorption isotherm of SDS is obtained. In the simultaneous adsorption of PVcA and SDS under fixed initial concentrations of PVcA, the amount of PVcA adsorbed increases and reaches a maximum, and then decreases with SDS concentration. The enhancement in the adsorption is due to the interaction between SDS and PVcA as confirmed by surface tensiometry. The dispersion stability of alumina suspensions by the simultaneous adsorption of PVcA and SDS is considerably high compared with that by SDS adsorption alone. The high dispersion stability is due to the extended conformation of the adsorbed PVcA and the electrostatic repulsion force. Further, the mobility of SDS molecules in the PVcA-SDS adsorbed layer is found to be more restricted than that in the SDS adsorbed layer alone.

Maleic acid alkyl ester and N-alkyl maleamic acid monomers (RnMa and RnMaAm; n is alkyl chain length; n=6, 8, 10, 12, 14) were synthesized by the reaction of maleic anhydride with alkyl alcohol or alkylamine. The telomerization of RnMa or RnMaAm in the presence of alkanethiol as a chain transfer agent gave telomer-type anionic surfactants (xRnMa, xRnMaAm; x is total average number of alkyl chains; x=2.8–3.3) having multialkyl chains and multicarboxylate groups. Their surface-active properties were investigated by several techniques such as surface tension, foaming property, and emulsification power measurements. Critical micelle concentrations (CMC) of xRnMa were 1/110–1/14 of those of RnMa with the same alkyl chain length. xRnMa and xRnMaAm gave higher efficiencies in lowering the surface tension than RnMa and RnMaAm in aqueous solutions. In particular, the surface tension of 3.2R12MaAm was 24.4 mN m−1 at the CMC. Foaming abilities and foam stabilities of xRnMa and xRnMaAm were higher than those of RnMa and RnMaAm. The addition of 300 ppm of Ca2+ to the aqueous solutions rendered the telomers less surface active. Shaking the aqueous solutions of telomers with toluene emulsified them. The highly stable oil-in-water type emulsion was formed by using 3.0R10MaAm and 3.2R12MaAm, and the degree of emulsification was kept at a level of about 80% after 60 min of standing. Thus, telomer-type surfactants showed excellent surface activities that were superior to the corresponding monomers as well as to conventional surfactants. The relationship between alkyl chain length of the telomers and the properties of surface tension, foaming, and emulsification was unclear.

Direct measurements of interaction forces between α-alumina surfaces with coadsorbed anionic surfactant (sodium dodecyl sulfate (SDS) or lithium perfluorooctanesulfonate (LiFOS)) and nonionic polymer poly(vinylpyrrolidone) (PVP) at pH 3.5 are carried out by colloidal probe atomic force microscopy. In aqueous SDS solutions, the strength of interaction forces is found to depend on the initial SDS concentration, whereas in PVP solutions, the electric double layer interaction is completely screened due to the flat conformation of PVP on α-alumina. The interaction forces are dramatically different for the coaddition of SDS and PVP: electrostatic repulsion is observed above the critical aggregation concentration, and virtually no steric hindrance due to adsorbed polymer chains can be detected. These coaddition effects are attributed to the flat conformation of the adsorbed PVP and the formation of SDS−PVP surface complexes as confirmed by surface tensiometry. The LiFOS−PVP system exhibits characteristics simil...

N-(α-Carboxyalkyl)acrylamide telomer-type surfactants (xC n−1 AmAc where n is alkyl chain length=6, 8, 10, 12; and x is degree of polymerization=3.3–13.1) were synthesized by the telomerization of monomer (C n−1 AmAc) in the presence of the corresponding alkanethiol as a chain transfer agent and then investigated for their surface-active properties. xC n−1 AmAc telomers lowered the surface tension of aqueous solutions that were at pH 9–10. The critical micelle concentrations (CMC) of the telomers were lower than those of the monomers with the same alkyl chain length, and the CMC values shifted to lower concentrations with both increasing alkyl chain length and polymerization degree. xC9AmAc with x=3.3–6.3 gave the highest efficiencies in lowering the surface tension. The cross-sectional molecular areas per molecule of xC n−1 AmAc telomers were smaller than the values estimated on the assumption that they are assemblies of C n−1 AmAc monomer units. The foaming abilities and the foam stabilities were both in the orders of xC7AmAc>xC9AmAc>xC5AmAc>xC11AmAc. Mixtures of aqueous solutions of xC n−1 AmAc telomers and toluene formed oil-in-water emulsions. The emulsion-stabilizing abilities were in the orders of xC7AmAc>xC5AmAc>xC9AmAc=xC11AmAc. The addition of Ca2+ to the mixed solutions of telomers and toluene resulted in formation of water-in-oil type emulsions. Thus, the surface-active properties of the telomers were influenced significantly by the alkyl chain length and the polymerization degree of the telomers. In addition, these properties could be correlated with the hydrophilic-lipophilic balance (HLB); the highest surface activities were observed by using xC n−1 AmAc with HLB of 14–18.

The physicochemical properties of quaternized poly(amidoamine) dendrimers (generation 4) with methyl or octyl groups and of their mixtures with sodium dodecyl sulfate (SDS) in aqueous solutions have been investigated using several techniques including surface tension, fluorescence of pyrene, and dynamic light scattering. In the single systems of the dendrimers, the dendrimer with octyl groups shows lower surface tension and lower micropolarity than the dendrimer with methyl groups. The hydrodynamic radii of two quaternized poly(amidoamine) dendrimers are considerably large, indicating the formation of aggregates. In the mixed systems of quaternized poly(amidoamine) dendrimers and SDS, the dendrimer with octyl groups–SDS mixed system shows very low surface tension and low micropolarity even in the presence of extremely low SDS concentration compared to those of the dendrimer with methyl groups–SDS mixed system. Maximum turbidity for both systems is observed at around the mixed molar ratio of dendrimer:SDS=1:1.5 where distinct changes have also been confirmed by surface tension, fluorescence of pyrene, and electrical conductivity measurements.

The interactions between poly(amidoamine)dendrimer(generation,4) with octyl end groups and surfactants such as sodium dodecyl sulfate (SDS), dodecyltrimethyl ammonium bromide (DTAB), and hexaoxyethylenedodecyl ether (C12E6) in aqueous solutions have been investigated by surface tension, fluorescence spectra of pyrene, and dynamic light scattering measurements. The results of dynamic light scattering and surface tension measurements indicate that the dendrimer molecules are aggregated in the absence and presence of the surfactants and they are adsorbed at the air–water interface, resulting in the remarkable reduction of surface tension of water. From the measurements of pyrene fluorescence spectra it is suggested that the dendrimer–SDS system provides much lower micropolarity environment than those for the dendrimer–DTAB or C12E6 system. The mechanisms for the interactions between the dendrimer and surfactants have been discussed.

Aqueous suspensions of 5-(3-ethoxy-4-pentyloxyphenyl)-2,4-thiazolidinedione (CT112) were prepared by neutralization of alkaline solutions of CT112 in the presence of surfactant and polymer. The formation of CT112 particles was kinetically studied by measuring the change of backscattering percent of the suspensions with time after neutralization. The rate of particle formation in the presence of sodium dodecyl sulfate (SDS) was much faster than those in the presence of celluloses while the particle size obtained in the presence of SDS was much smaller than those in the presence of celluloses. In the presence of both SDS and celluloses, stable aqueous dispersions of CT112 were obtained. The mechanisms of particle formation of CT112 as well as dispersion stability were also discussed.

The surface activities of mixed surfactants of partially-quaternized 2-vinylpyridine telomers (xRn-2VPQ, x is the total number of alkyl chains, n is the alkyl chain length) and monomeric alkyltrimethylammonium bromide (1RnQ) or gemini 1, 2-bis (alkyldimethylammonio) ethane dibromide (2RnenQ) were investigated at pH 2 by surface tension, foaming property, interfacial tension and emulsification power. The mixed critical micelle concentrations (cmcs) were intermediate between the pure component xRn-2VPQ and 1RnQ or 2RnenQ. xRn-2VPQ/2RnenQ system was higher efficiencies in lowering the surface tension than xRn-2VPQ/1RnQ. The surface tension was influenced by the alkyl chain length of binary surfactants and the mole fraction (α) of xRn-2VPQ. In particular, 2.0R10-2VPQ/2R10enQ system with α = 0.50 showed the lowest surface tension. The mixtures of two cationic multialkylated surfactants improved the foaming properties as compared with the pure component cationic surfactants. The similar trends in the surface tension and the foaming properties were observed for the lowering abilities of the interfacial tension at the water / toluene interface and emulsion stabilities.

Telomerization of N-alkyl maleamic acid monomer (RnMaAm, n is the alkyl chain length; n=6-14), which was synthesized by reaction of maleic anhydride with alkylamine, in the presence of alkanethiol as a chain transfer agent gave the telomers (xRnMaAm, x is total number of alkyl chains; x=2.9-3.2) in 60-90% yields. The surface-active properties such as surface tension, foaming property and emulsion stability were examined in water as well as in hard water containing 300 ppm of Ca2+. The critical micelle concentrations (cmcs) of 2.9-3.2RnMaAm telomers were 1/142-1/42 of those of RnMaAm monomers with the same alkyl chain length. The surface tensions of aqueous solutions of RnMaAm monomers and 2.9-3.2RnMaAm telomers were 30-35 and 24-32 mN m-1, respectively. The addition of Ca2+ to the aqueous solutions of 2.9-3.2RnMaAm lowered the cmc, while gave a low efficiency at reducing the surface tension. Of the telomers, 3.0R12MaAm gave the highest foaming ability and the highest foam stability in water. Shaking of the mixtures of organic solvent and the aqueous solutions of xRnMaAm telomers formed oil-in-water type emulsions. The emulsion stabilities were in the orders of toluene > n-octane > n-dodecane > n-hexadecane > kerosene as an oil phase. The highly emulsions for toluene or n-dodecane were formed by using 3.0R8MaAm and 3.0R10MaAm. The aqueous solutions of RnMaAm monomers and 2.9-3.2RnMaAm telomers gave interfacial tension of 8-10 and 4-6 mN m-1, respectively, for the interface with toluene. Thus, N-alkyl maleamic acid telomer type anionic surfactants having several alkyl chains showed greater surface activities than the corresponding monomeric monomers as well as the conventional surfactants.

The adsolubilization of 2-naphthol by mixtures of an anionic surfactant, sodium dodecyl sulfate (SDS), and nonionic surfactants, hexaoxyethylenedecyl ether (C 1 0 E 6 ), and hexaoxyethylenedodecyl ether (C 1 2 E 6 ) on alumina was investigated. Adsorption and adsolubilization were performed using a feed concentration of SDS under various fixed concentrations of the nonionic surfactants. The adsolubilization of 2-naphthol increased with an increase of the fixed nonionic surfactant concentration, showed a maximum and then decreased with a further increase of nonionic surfactant concentration for both SDS/C 1 0 E 6 and SDS/C 1 2 E 6 systems. The adsolubilization of 2-naphthol was greater for SDS/C 1 0 E 6 and SDS/C 1 2 E 6 systems than that for SDS single system. Furthermore, the adsolubilization efficiency defined by ratio of 2-naphthol adsolubilized to total surfactant adsorbed amount was higher for SDS/C 1 2 E 6 system than that for SDS/C 1 0 E 6 system at the maximum adsolubilization. This difference in the efficiency between SDS/C 1 0 E 6 and SDS/C 1 2 E 6 systems is attributed to the properties of the mixed-surfactant adsorbed layer which are affected by the hydrocarbon chain lengths of nonionic surfactants.

Gold nanoparticles are prepared in aqueous solutions by using poly (amidoamine) (PAMAM) dendrimers (generation 3.0, 3.5, 5.0 0 and 5.5) with various terminal groups such as methyl ester, amino, carboxyl, or sugar residue,and their mean particle sizes are 2-6 nm in diameter depending on the dendrimer/Au + 3 ratio as well as the generation of PAMAM dendrimers. Studies of reduction reaction of 4-nitrophenol by gold nanoparticles with NaBH 4 reveal that the rate constant depends on the concentration of the dendrimers added as well as the generation of the dendrimers. Furthermore, the effect on the rate constants for PAMAM (generation 5.0 and 5.5) with various terminal groups follows the order : carboxyl ≥ amino > sugar residue > methyl ester. These results are attributed to the dendrimer-gold nanocomposite structures, depending on whether the gold nanoparticles are formed inside or outside the dendrimers.

Adsorption behaviors of poly(ethyleneglycol) and poly(amidoamine)dendrimer with surface carboxyl group on alumina and silica in aqueous solutions were studied at pH 5. Poly(amidoamine)dendrimer adsorbed considerably on both alumina and silica, while poly(ethyleneglycol) adsorbed preferably on silica to alumina. In a simultaneous adsorption of poly(ethyleneglycol) and poly(amidoamine)dendrimer at a constant initial concentration of poly(ethyleneglycol), competitive effects are for poly(ethyleneglycol) at all concentrations and for poly(amidoamine)dendrimer at higher concentrations only for both alumina and silica particles. The ζ potential and sedimentation rates of the suspensions were affected by adsorption of the polymers. The adsorption mechanism of the polymers on alumina and silica was discussed.

The adsolubilization of 2-naphthol by binary mixtures of cationic and nonionic surfactants on silica was investigated. Two cationic surfactants used were hexadecyltrimethylammonium bromide (HTAB) and 1,2-bis(dodecyldimethylammonio)ethane dibromides (2RenQ), and a nonionic surfactant used was hexaoxyethylenedecyl ether (C10E6). In the single surfactant systems, adsolubilization of 2-naphthol for HTAB and 2RenQ was very similar and was greater than that for C10E6. In the HTAB/C10E6 system the adsolubilization of 2-naphthol was enhanced by surfactant mixtures of HTAB and C10E6 compared to those of single systems. However, in the 2RenQ/C10E6 system the adsolubilization of 2-naphthol by surfactant mixtures of 2RenQ and C10E6 was rather smaller than that of 2RenQ alone but still larger than that of C10E6. It is found that the adsorbed layers of surfactant mixtures formed from different surfactant structures exhibit different adsolubilization behaviors of 2-naphthol, and the alkyl chain length of the surfactants...

Interactions between alkanethiols and gold−dendrimer nanocomposites in ethyl acetate were investigated by adding alkanethiols such as 1-decanethiol and 1,10-decanedithiol into gold−poly(amidoamine)dendrimer nanocomposites. Poly(amidoamine)dendrimers with surface methyl ester groups used were generations of 1.5 and 5.5 (G1.5 and G5.5). The mean particle sizes of gold−dendrimer nanocomposites were about 2.1 nm for G1.5 and 2.4 nm for G5.5. In the case of gold−dendrimer(G1.5) nanocomposites, the addition of 1-decanethiol led to smaller gold particles, while that of 1,10-decanedithiol provided the formation of large, highly regular, spherical clusters with diameters of 40−60 nm. On the other hand, in the case of gold−dendrimer(G5.5) nanocomposites the addition of 1-decanethiol showed a distinct tendency into smaller and larger spheres, whereas that of 1,10-decanedithiol provided irregular spherical clusters with diameters of 30 nm. The mechanisms for morphology changes in the gold−dendrimer nanocomposites by ...

The interaction of tetrachloroauric anion (AuCl4−) and hydrophobic poly(amidoamine) dendrimers (PAMAM) with terminal methyl ester groups was investigated in ethyl acetate by UV–vis and IR spectroscopies. Three possible types of interaction are suggested: (a) ion pair formation between AuCl4− and protonated tertiary amine of PAMAM, (b) chelation of Au(III) by one (or two) tertiary amine(s) and two terminal methyl ester groups, and (c) chelation of Au(III) by two tertiary amines and two adjacent amide groups of the dendrimer. Au–PAMAM nanocomposites were synthesized by reducing the AuCl4−–PAMAM complex with dimethylamine borane. The structure of the nanocomposites is supposed to be of exterior or mixed type. These Au–PAMAM nanocomposites exhibit a weak surface plasmon band in the range of 480 to 500 nm.

Gold nanoparticles were prepared by reduction of HAuCl4 with NaBH4 in the presence of poly(amidoamine)dendrimers with surface methyl ester groups in formamide or N,N-dimethylformamide. Although solutions of HAuCl4 in formamide, in the presence of the dendrimers, were reduced to some extent before reduction, the addition of NaBH4 provided gold nanoparticles whose size decreased with an increase of the dendrimer generation as well as with the concentration of the dendrimers. On the other hand, gold nanoparticles prepared in N,N-dimethylformamide in the presence of the dendrimer were highly monodispersed. In addition, we discussed how the dendrimers acted as templates for the preparation of gold nanoparticles.

Interaction forces between glass surfaces with covalently attached quaternary ammonium groups (XNm, m is the carbon number of alkyl chains) in aqueous ionic surfactant solutions have been studied b...

Mixed aqueous properties of sugar-persubstituted poly(amidoamine) dendrimers (generation, 3.0 and 5.0) (sugar ball) and anionic surfactants, such as sodium dodecyl sulfate (SDS) and lithium perfluorooctanesulfonate (LiFOS), were investigated. The surface tensions of the mixtures of sugar balls and anionic surfactants at several fixed concentrations of sugar balls decreased sharply at low surfactant concentration, remained constant and then increased with a further increase of the surfactant concentration where the lower the surface tensions, the smaller the fixed concentration of the sugar balls. From the measurements of pyrene and 1-(perfluorooctanoyl)pyrene fluorescence spectra, it is suggested that aggregates between the anionic surfactants and sugar balls are formed, showing a hydrophobic environment. The mechanism for the aggregation formation is discussed.

Cotelomer type zwitterionic surfactants having multi-hexyl chains and multi-carboxylate and muti-pyridinium functions (R6S-zR6VPQ-wVP-yAA, w and y means the number of 4-vinylpyridine and sodium acrylate, respectively; z means number of hexyl chains by quaternization) were prepared by quaternization and hydrolyses of cotelomers, which were prepared by cotelomerization of 4-vinylpyridine and methyl acrylate in presence of hexanethiol, and examined for their surface activities. Critical micelle concentration (cmc) of zwitterionic cotelomers shifted to lower concentration with increasing number of hexyl chains. The cmcs of R6S-zR6VPQ-wVP-yAA with z of 2.1-3.8 were from one 110th to one 4th of those of the corresponding cationic cotelomers. Zwitterionic cotelomers gave surface tension of 40-44 mN m-1 at the cmc. The increase of number of hexyl chains in R6S-zR6VPQ-wVP-2.3AA series reduced the surface activities. Vigorous shaking of the mixtures of water and chloroform solution of zwitterionic cotelomers formed oil-in-water type emulsion. Highly stable emulsion was formed by using R6S-zR6VPQ-wVP-2.3AA with z of 1.4-2.1 and the degrees of emulsification were kept at the level of 60-70% after 360 min of standing. Zwitterionic cotelomers gave interfacial tension of 2-4 mN m-1 at the water-chloroform interfaces and oriented themselves easier than equimolar mixtures of cationic cotelomer and anionic cotelomer.

Complexane-type trimeric surfactants of tris(1-carboxyalkyl-2-aminoethyl)amine (3Rntata; n means alkyl chain length, n=6-14) having three alkyl chains and three hydrophilic groups were prepared by the reaction of tris(2-aminoethyl)amine and 2-bromoalkanoic acid and examined for surface activities such as surface tension, emulsification and interfacial tension. Critical micelle concentration (cmc) of 3Rntata shifted to lower concentration with increasing alkyl chain length. The cmcs of 3Rntata with n of 10-14 were lower by about 1-2 orders of magnitude than those of complexane-type monomeric surfactant of 2-aminoalkanoic acid (RnNAc) and dimeric surfactant of N, N″-bis(1-carboxyalkyl)diethylenetriamine (2Rndtda) with the same alkyl groups. In the case of R12, 3Rntata gave about twice cmc of trimeric surfactant of (N1-carboxyalkyl-2-aminoethyl)alkyllamine (3Rntata) having three alkyl chains and two hydrophilic groups. Surface tension at each cmcs of 3R10tata, 3R12tata, and 3R14tata was 33.0, 26.9 and 29.6 mN m-1, respectively. 3R12tata, and 3R14tata gave more efficient in lowering the sufface tension than RnNAc and 2Rndtda. The values of cross-sectional molecular area (A) of 3Rntata with n of 10-14 were 42-75A2. They were extremely small in comparison with three times of A of RnNAc. The aqueous solutions of 3Rntata were emulsified by shaking with toluene. Highly stable oil-in-water type emulsion was formed by using 3Rntata with n of 10-14 and the degree of emulsification was kept 60% after 20 h. Interface between the aqueous solutions of 3R10tata, 3R12tata, 3R14tata and toluene gave the interfacial tension of 1, 1 and 6 mN m-1, respectively.

The effect of surfactant and polymer on dispersion stability of aqueous suspensions of 5-(3-ethoxy-4-pentyloxyphenyl)-2,4-thiazolidinedione (CT112) was investigated by measuring the adsorbed amount of surfactant and polymer, zeta potential, particle size, and sedimentation rate of CT112. The addition of celluloses rather than sodium dodecyl sulfate (SDS) provided a high stable suspension of CT112. In addition, mixed systems of celluloses and SDS enhanced CT112 dispersion more effectively. The mechanism of dispersion stability of CT112 by addition of SDS and celluloses is discussed.

Cotelomers of acryric acid and n -octyl acrylate, 2-ethylhexyl acrylate or 2-phenylethyl acrylate with same carbon numbers (abbreviation by 2.1NoA-1.2AA, 1.9EhA-2.9AA and 1.6PeA-3.0AA, respectively; 2.1, 1.9 and 1.6 mean number of hydrophobic functions, 1.2, 2.9 and 3.0 mean number of carboxylate functions) were prepared by the radical cotelomerization in presence of 2-aminoethanethiol hydrochloride and examined for surface activity. Critical micelle concentrations (cmcs) of 2.1NoA-1.2AA, and 1.9EhA-2.9AA were 1/16 and 1/5 of that of conventional surfactant of sodium n -octanoate. Surface tensions of aqueous solutions of 2.1NoA-1.2AA, 1.9EhA-2.9AA and 1.6PeA-3.0AA were 32.3, 27.3 and 41.1 mN m-1 at each cmc, respectively. 2.1NoA-1.2AA having straight alkyl chains and 1.9EhA-2.9AA having branched alkyl chains gave figh foaming abilities in water as well as in hard water. 2.1NoA-1.2AA had high foam stability, while 1.9EhA-2.9AA showed poor stability. The highly stable oil-in-water type emulsions, which were brought about by shaking toluene with aqueous solutions of cotelomers, were formed by using 1.6PeA-3.0AA having aromatic nucleus. Interfacial tensions between aqueous solutions of 2.1NoA-1.2AA, 1.9EhA-2.9AA and 1.6PeA-3.0AA and toluene were 4, 8 and 1mN m-1, respectively.

Transition metal (Fe, Co or Ni) dispersed carbon composites were prepared using the mixtures of metal acetylacetonate complex as a source of metal particles and an anisotropic coal-tar pitch as a carbon matrix precursor by heat treatment at the temperatures up to 1000°C. Mixing of the metal complexes and the pitch by dissolving in quinoline permitted the notable fine dispersion of the complex in the pitch. Then the resulting mixtures were easily converted to the metal dispersed carbons by pyrolysis under an inert atmosphere. The appeared particles were Fe3O4/α-Fe/Fe3C, β-Co or Ni when using the corresponding metal complex. Besides, their particle diameters were much less than 30 nm and distributed evenly throughout the carbon matrix. The magnetic properties of the metal dispersed carbons were evaluated with a vibrating sample magnetometer, and it was found that saturation magnetization and coercive force ranged from 1.03 × 10−5 to 5.65 × 10−5 Wb · m/kg and from 0.21 × 104 to 3.06 × 104 A/m, respectively.

Adsorption of ionic surfactants on titanium dioxide with dodecyl chain groups or quaternary ammonium groups (XN m , where m is the carbon number of the alkyl chain, 4–16) was investigated. The adsorbed amount of cationic surfactants (dodecyltrimethylammonium bromide, DTAB; 1,2-bis(dodecyldimethylammonio)ethane dibromide, 2RenQ) on titanium dioxide with dodecyl chain groups increased with increasing concentration of the dodecyl chain due to hydrophobic interaction, where the adsorbed amounts of DTAB at saturation was considerably greater than those of 2RenQ. Adsorption of an anionic surfactant (sodium dodecyl sulfate, SDS) on XN m occurred mainly due to both electrostatic attraction force and hydrophobic interaction, depending on the alkyl chain length on XN m. On the other hand, adsorption of cationic surfactants, DTAC and 2RenQCl (their counter ions are chloride ions), on XN m was quite smaller compared with that of SDS due to electrostatic repulsion force. Adsolubilization of 2-naphthol in the surfactant-adsorbed layer on the titanium dioxides with the functional groups was also studied. The adsolubilized amounts of 2-naphthol on titanium dioxide with dodecyl chain groups were enhanced by adsorption of DTAB, but no distinct increase in the adsolubilization was observed by adsorption of 2RenQ. In the case of XN m , the amount of 2-naphthol adsorbed in the absence of surfactants increased with increasing alkyl chain length on XN m . Further, an appreciable increase in the adsolubilization of 2-naphthol on XN m with adsorption of 2RenQCl was observed. It was found from the admicellar partitioning coefficients that the adsolubilization of 2-naphthol preferably occurs on XN m by adsorption of SDS or 2RenQCl compared with that by DTAC. These differences in the adsolubilization were discussed by microproperties of the surfactant-adsorbed layers estimated using a spin probe.

The simultaneous adsorption of sugar-persubstituted poly(amidoamine) dendrimers (sugar ball) and anionic surfactants such as sodium dodecyl sulfate (SDS) and lithium perfluorooctanesulfonate (LiFOS) on positively charged alumina particles was investigated at pH 3.5 by measuring the amount of adsorbed sugar ball and anionic surfactant, ζ potential, and sedimentation rate of alumina suspensions. The sugar balls of generations G3 and G5 were used. Under constant initial concentrations of the sugar balls, the amount of adsorbed sugar balls sharply increases, reaches a maximum, and then decreases, while the anionic surfactant adsorption increases with increasing anionic surfactant. The enhancement in the adsorption of the sugar balls is due to the adsorption of complexes consisting of sugar ball and anionic surfactant. In addition, the dispersion stability of alumina suspensions caused by the adsorption of the sugar ball and anionic surfactant depends on the ζ potential of alumina as well as the adsorption of ...

The adsolubilization of 2-naphthol by surfactant mixtures of an anionic surfactant, sodium dodecyl sulfate, and a nonionic surfactant, hexaoxyethylenedodecyl ether on alumina was investigated. In a single-surfactant system, only the anionic surfactant was found to show an appreciable adsolubilization. In the mixed-surfactant system, the adsolubilization grew with an increase in the total amount of adsorbed surfactant, whereas the adsolubilization became greater with an increase in the anionic surfactant content in the initial mixtures. On the other hand, the ratios of adsolubilized amount to surfactant adsorbed amount became smaller when the anionic surfactant content in the initial mixtures increased. This behavior is attributed to the properties of the mixed-surfactant adsorbed layer at the alumina−water interface.

Interactions between poly(amidoamine)dendrimers with surface carboxyl groups and cationic surfactants in aqueous solutions were investigated by surface tension, fluorescence spectra, and dynamic scattering measurements. The dendrimers used were three generations (G1.5, 3.5, and 5.5) and two cationic surfactants were dodecyltrimethylammonium bromide (DTAB) and 1,2-bis(dodecyldimethylammonio)ethane dibromide (2RenQ). Under a constant concentration of surface groups of the dendrimers, the results of surface tension and fluorescence spectra measurements indicate that aggregates between DTAB and the dendrimers are formed at lower DTAB concentration than that of DTAB alone, whereas those between 2RenQ and the dendrimers are formed at higher 2RenQ concentration than that of 2RenQ alone. In addition, the aggregates show higher surface activity when the generation decreases from 5.5 to 1.5. Hydrodynamic radius obtained from dynamic scattering measurement suggests that the aggregates are formed by adsorbing surfactant on the surface of the dendrimers, not by bridging the dendrimers through the surfactant.

Stable nanosize gold and silver particles are spontaneously formed by reduction of aqueous metal salt solutions in the presence of sugar-persubstituted poly(amidoamine) dendrimers (sugar ball). Two sugar balls consisting of generations 3 and 5 are used. The nanoparticles are characterized by absorption spectroscopy, electron microscopy, and FT-IR spectroscopy. In the formation of silver particles, alkaline solution is required. In the process of reduction, characteristic absorption bands appear for the respective metal particles and the intensities increase with reaction time. The sigmoidal curve of intensity vs the reaction time suggests an autocatalytic reaction. The apparent rate constants for the formation of gold particles increase with the concentration of sugar ball, where the rate constants are greater for generation 3 than for generation 5 at the same weight percent of sugar ball. On the other hand, an opposite trend is observed for the formation of silver particles. The average diameters of gold and silver range between 2 and 6 nm and their size distributions are relatively wide.

Nanoparticles of gold, platinum, and silver were prepared by reduction of their metal salts with NaBH4 in the presence of poly(amidoamine) dendrimers. The dendrimers used were generation 3, 4, and 5 having surface amino group (G3, G4, and G5) as well as generation 3.5, 4.5, and 5.5 having surface carboxyl group (G3.5, G4.5, and G5.5). The metal nanoparticles obtained were characterized by UV−vis spectroscopy and transmission electron microscopy. By using G3−G5, gold nanoparticles in the 1.5−4.0 nm size regime were obtained where their size decreased with increasing concentration of the dendrimers as well as the generation of the dendrimers. Similarly, platinum nanoparticles with a diameter of 2.4−3.0 nm were obtained, and their size was insensitive against the concentration as well as the generation of G3−G5. In the case of silver nanoparticles, very small silver particles using G3.5−G5.5 were obtained. In addition, the dendrimer concentration required for obtaining stable nanoparticles was found to be de...

The interactions of sugar-persubstituted poly(amidoamine) dendrimers (generation, 3.0 and 5.0) (sugar ball) with anionic surfactants such as sodium dodecyl sulfate (SDS) and lithium perfluorooctanesulfonate (LiFOS) were investigated at a constant concentration of the sugar ball. At low surfactant concentrations, aggregates of the anionic surfactants at the surface of the sugar ball are formed, showing a strong surface activity. The size of the mixed aggregates increases with the anionic surfactant concentration, and also depends on the generation of the sugar ball: the size for generation 3.0 is greater than that for generation 5.0. The association process is also affected by the kind of hydrophobic chain of the surfactant. These differences reflect solubilization behaviors of biphenyl and decafluorobiphenyl into the mixed systems of the sugar ball and the surfactant.

Complexane-type surfactants possessing two and three alkyl chains (2Rnida, 2Rnedda, 2Rndtda and 3Rndtda; n means alkyl chain length) were prepared by the corresponding amine and the appropriate alkyl bromide and examined for surface activity. Critical micelle concentration (cmc) was found to shift to lower concentration with increase in alkyl chain length, number of alkyl chains and decrease in spacer length. Cmcs of 3R8dtda and 3R12dtda having three alkyl chains were 2-3 smaller than that of the corresponding surfactant having one alkyl chain. Surface tension of complexanes was significantly affected by alkyl chain and spacer length and the number of alkyl chains. Surface tension of 3R8dtda attained to 24.0mN m-1 at cmc. Cross-sectional molecular areas of 3Rndtda with n=6-12 were extremely small in comparison with three times of that of R12NAc and those of 2Rnida, 2Rnedda and 2Rndtda. Complexane solution was emulsified by shaking with toluene. 2R12ida showed a stable water-in-oil type emulsion and 2Rnedda and 2Rndtda with n=10-12 and 3R8dtda each showed a high oil-in-water type emulsion. Interfacial tension between toluene and complexane solution was 1-2mN m-1 for complexanes with n=12. Multi-alkylated complexanes with HLB of about 22 showed the greatest surface activity. 3R8dtda was a more efficient surfactant at air/water and toluene/water interfaces.

Hyperbranched polymers or dendrimers have been of considerable interest since the mid 1980s. Nanocomposites consisting of dendrimers and various metal nanoparticles have been synthesized for use in the preparation of highly functional materials such as substrate-selective catalysts and chemical sensors. The synthesis and applications of dendrimer-metal nanocomposites mainly for poly (amidoamine) dendrimers are discussed in this paper.

As one of applications of adsolubilization, a simultaneous sorption of 2-naphthol and copper ions by cationic surfactant-adsorbed laponite was carried out. Both the surfactant-adsorbed laponite using dodecyl trimethylammonium bromide (DTAB) and 1,2-bis(dodecyldimethylammonio) ethane dibromide (2RenQ) retained a high sorption capacity for copper ions, while the 2RenQ-adsorbed laponite completely adsolubilized 2-naphthol in a whole concentration region, but the DTAB-adsorbed laponite one decreased the adsolubilization gradually above the cmc of DTAB. Thus, it was found that laponite having cationic surfactant-adsorbed layer has a great capacity for a simultaneous removal of both toxic nonionic and ionic compounds.

Simultaneous adsorption of sodium dodecyl sulfate (SDS) and poly(vinyl pyrrolidone) (PVP) on titanium dioxide with quaternary ammonium groups (XNm, where m is the carbon number of the alkyl chain, 8 and 12) was investigated by measuring the amount of adsorbed SDS and PVP, ζ potential, and dispersion stability. The conformation of PVP adsorbed was also estimated using a spin-labeled polymer. The amount of SDS adsorbed on XNm in the presence of PVP was enhanced at low SDS concentrations, but was depressed at high SDS concentrations compared with that in the absence of PVP. Further, the amounts of SDS adsorbed on XNm in the presence and in the absence of PVP were greater than that on untreated titanium dioxide. The adsorption of PVP was remarkably enhanced at low SDS concentrations, followed by a dramatic decrease at high SDS concentrations for XNm and untreated titanium dioxide. The results of ESR measurements indicate that the PVP adsorbed on XNm in the absence and in the presence of SDS takes mainly train conformation, while the PVP adsorbed on untreated titanium dioxide in the absence of SDS takes loops or tails and converts to train conformation in the presence of SDS. In addition, the dispersion stability of XNm and untreated titanium dioxide suspensions increased at low SDS concentrations in the presence of PVP compared to that in the absence of PVP.

The simultaneous adsorption of poly(amidoamine) dendrimers with surface carboxyl groups and an anionic surfactant, sodium dodecyl sulfate (SDS), on positively charged alumina particles was investigated at pH 5 by measuring the amount of adsorbed dendrimers and SDS, ζ potential, and sedimentation rate of alumina suspensions. The dendrimers of generations G1.5 and G5.5 were used. Under constant feed concentrations of the dendrimers, the amount of adsorbed dendrimers gradually decreased, while SDS adsorption increased with increasing SDS concentration for both SDS/G1.5 and SDS/G5.5 systems, indicating a competitive adsorption between the dendrimers and SDS. A preferential adsorption of G5.5 over G1.5 in the competitive adsorption with SDS was also observed. The difference in the adsorption of the dendrimers reflected the sedimentation rate of alumina suspensions; the feature of the sedimentation rate with SDS concentration for the SDS/G1.5 system was very similar to that for the SDS system alone, but differe...