Dependency of particle sizes and colloidal stability of polyelectrolyte complex dispersions on polyanion structure and preparation mode investigated by dynamic light scattering and atomic force microscopy

Polyelectrolyte complex (PEC) dispersions were prepared by controlled mixing of three random copolymers of sodium 2-acrylamido-2-methylpropanesulfonate (AMPS) with either t-butyl acrylamide (TBA) [P(AMPS54-co-TBA46) and P(AMPS37-co-TBA63)] or methyl methacrylate (MM) [P(AMPS52-co-MM48)] with an ionene-type polycation, containing 95 mol % N,N-dimethyl-2-hydroxypropyleneammonium chloride repeat units (PCA5), with their structural characteristics being deeply investigated by dynamic light scattering (DLS) and atomic force microscopy (AFM). Shape, size, and polydispersity of the PEC dispersions were directly observed by AFM as a function of polyanion structure, the ratio between charges, n-/n+, and the titrant addition rate (TAR). The particle sizes increased and the colloidal stability decreased with the increase of the nonionic comonomer content and with the decrease of TAR. It was demonstrated that the medium particle sizes of the complex nanoparticles adsorbed on silicon wafers measured by AFM, in the dry state, were close but always lower than those measured by DLS, both before and after the complex stoichiometry.     

Polyelectrolyte complexes. VI. Polycation structure,polyanion molar mass,and polyion concentration effects on complex nanoparticles based on poly(sodium 2‐acrylamido‐2‐methylpropanesulfonate)

The formation and characterization of some interpolyelectrolyte complex (IPEC) nanoparticles based on poly(sodium 2‐acrylamido‐2‐methylpropanesulfonate) (NaPAMPS), as a function of the polycation structure, polyanion molar mass, and polyion concentration, were followed in this work. Poly(diallyldimethylammonium chloride) and two polycations (PCs) containing (N,N‐dimethyl‐2‐hydroxypropyleneammonium chloride) units in the backbone (PCA₅ and PCA₅D₁) were used as starting polyions. The complex stoichiometry, (n^?/n⁺)_iso, was pointed out by optical density at 500 nm (OD₅₀₀), polyelectrolyte titration, and dynamic light scattering. IPEC nanoparticle sizes were influenced by the polycation structure and polyanion molar mass only before the complex stoichiometry, which was higher for the more hydrophilic polycations (PCA₅ and PCA₅D₁) and for a higher NaPAMPS molar mass, and were almost independent of these factors after that, at a flow rate of the added polyion of about 0.28 mL × (mL PC)^?1 × h^?1. The IPEC nanoparticle sizes remained almost constant for more than 2 weeks, both before and after the complex stoichiometry, at low concentrations of polyions. NIPECs as stable colloidal dispersions with positive charges in excess were prepared at a ratio between charges (n^?/n⁺) of 0.7, and their storage colloidal stability, as a function of the polycation structure and polyion concentration (from 0.8 to ca. 7.8 mmol/L), was demonstrated. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2495–2505, 2004     

Polyelectrolyte complexes. VII. Complex nanoparticles based on poly(sodium 2‐acrylamido‐2‐methylpropanesulfonate) tailored by the titrant addition rate

Nonstoichiometric interpolyelectrolyte complexes (IPECs) as colloidal dispersions have been widely used for the past decade as reactive materials for flocculation and surface modification. In this context, some new aspects of the preparation and properties of IPEC nanoparticles based on NaPAMPS, in salt‐free aqueous solutions, are reported in this article. IPEC dispersions with different characteristics, z‐averaged particle sizes, polydispersity indices, and colloidal stabilities were tailored by the addition rate of the titrant, a less investigated factor in the synthesis of IPECs as nanoparticles. Poly(sodium 2‐acrylamido‐2‐methylpropanesulfonate) (NaPAMPS) and two polycations bearing positive charges in the backbone, poly(diallyldimethylammonium chloride) and a polycation containing 95 mol % N,N‐dimethyl‐2‐hydroxypropyleneammonium chloride units, were used for this purpose. The complex nanoparticle characteristics and storage stability were monitored via the optical density at 500 nm and dynamic light scattering. IPEC nanoparticles with z‐averaged particle sizes of 100–250 nm resulted from the same polyion pair and the same polyion concentrations when the addition rate of the titrant, either the polyanion or polycation, varied within the range of 0.1–1.5 mL/mL of the starting polyion × h. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5244–5252, 2004     

Transport properties of ions through temperature-responsive charged membranes prepared using poly(vinyl alcohol)/poly(N-isopropylacrylamide)/poly(vinyl alcohol-co-2-acrylamido-2-methylpropane sulfonic acid)

Temperature-responsive charged membranes were prepared from the polymer mixture of poly(vinyl alcohol) (PVA), in situ polymer of N-isopropylacrylamide (NIPAAm) and PVA, and a polyanion [poly(vinyl alcohol-co-2-acrylamido-2-methylpropane sulfonic acid)]. The membranes were cross-linked under several conditions. The relationship between the preparation conditions and the water content response to temperature change, rH, and the charge density response to temperature change, rCx, was investigated. The membrane cross-linked with glutaraldehyde after annealing has the highest rH and rCx in all the membranes. rCx decreases with increasing polyanion content, and increases with increasing poly(NIPAAm) content. Permeation experiments in a dialysis system consisting of the membrane and mixed KCl and CaCl₂ solutions show that the transport modes of Ca²⁺ ions through the membrane are controlled by temperature changes in two ways: downhill transport (transport along their own concentration gradient in a system) at temperatures below the lower critical solution temperature (LCST) of poly(NIPAAm); uphill transport (transport against their concentration gradient) at temperatures above the LCST.     

聚丙烯酸钠与聚(苯乙烯-co-4-乙烯基吡啶)阳离子复合作用的研究

聚电解质复合物 (Ｐｏｌｙｅｌｅｃｔｒｏｌｙｔｅｃｏｍｐｌｅｘ)是指带有相反电荷的两种聚电解质之间通过库仑力而结合形成的一类特殊的高分子材料[1 ] .由于生物体内的很多反应以及生物化学合成过程都是通过高分子复合物进行的 ,因此对高分子间相互作用及其聚集体形成的研究受到了人们的极大重视 .目前研究得较多的体系是聚苯乙烯衍生物 ,如Ｉｏｐｌｅｘ 1 0 1即由聚苯乙烯磺酸钠和聚氯化乙烯基苄基三甲基铵反应而得[2 ,3] .本文报道了不同电荷密度及相对分子质量的聚苯乙烯 ｃｏ 4 乙烯基吡啶的硫酸甲酯盐 ,与不同分子质量的聚丙烯酸钠…     

Polyelectrolyte complexes. II. Specific aspects of the formation of polycation/dye/polyanion complexes

We report on the formation of the polycation/dye/polyanion (PC/D/PA) complexes by the interaction between nonstoichiometric polycation/dye (PC/D) complexes with polyanions. Polycations differed in their content of the (N,N‐dimethyl‐2‐hydroxypropylene ammonium chloride) units in the main chain. Poly(sodium acrylate) (NaPA), poly(sodium 2‐acrylamido‐2‐methylpropane sulfonate) (NaPAMPS) and poly(sodium styrenesulfonate) (NaPSS) were used as polyanions. Crystal Ponceau 6R (CP6R) and Ponceau 4R (P4R) with two or three sulfonic groups were used as anionic dyes. The interaction between nonstoichiometric PC/D complexes and polyanions was followed by UV‐VIS spectroscopy, viscometry, and conductometry measurements. Formation of PC/D/PA complexes takes place mainly by the electrostatic interaction between the polyanion and the free positive charges of the nonstoichiometric PC/D complex. The stoichiometry and the stability of the tricomponent complexes depended on the polycation structure, the structure and molecular weight of polyanion, the dye structure, and the P/D molar ratio. A high amount of the dye was excluded from the complex before the end point when a branched polycation was used. The higher the solubility of the dye the lower the stability of the PC/D/PA complexes. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 409–418, 1999     

Reaktionen von bis(η-cyclopentadienyl)zirconiumhydriden mit (iminoacyl)zirconocen-komplexen

The reaction of imidoylzirconocene complexes with zirconocene hydrides yields (N-alkylamido)zirconocene complexes. For a mechanistic study, the specifically substituted imidoylzirconocene complexes 3b–3d have been prepared and treated with the oligomeric metal hydrides (Cp₂ZrH₂)_x (1b) and (Cp₂ZrHCl)_x (1c). (N-Benzyl formimidoyl)zirconocene chloride (3b) was obtained by treating 1c with benzyl isonitrile 2a. Treatment of dimethylzirconocene with 2a gave (N-benzyl acetimidoyl)methylzirconocene (3c), which was treated with PhICl₂ to give (N-benzylacetimidoyl)zirconocene chloride (3d). The reaction of 3d with (Cp₂ZrH₂)_x (1b) yielded (N-benzyl-N-ethylamido)zirconocene chloride (4b) as the only identified product. A 1/1 mixture of 4b and methylzirconocene chloride was obtained upon treatment of 3c with (Cp₂ZrHCl)_x (1c); in contrast, the reaction of 1c with 3b gave an equimolar mixture of Cp₂ZrCl₂ and (N-benzyl-N-methylamido)zirconocene chloride (4c). Reaction paths through binuclear (μ-CHR′=NR) zirconocene intermediates are proposed to explain these experimental observations.     

Effects of surfactants on foliar uptake of herbicides - a complex scenario

Novel organic–inorganic nanohybrids, each having an inorganic core covered with an asymmetric lipid-bilayer membrane, were prepared through two-step self-assembling of a Cerasome-forming organoalkoxysilane lipid, N-[N-(3-triethoxysilyl)propylsuccinamoyl]dihexadecylamine (1), as the inner layer with an appropriate bilayer-forming amphiphile, N,N-dihexadecyl-N-[6-(trimethylammonio)hexanoyl]alaninamide bromide (2), sodium N,N-dihexadecyl-N-(6-sulfohexanoyl)alaninamide (3), or dimyristoylphosphatidylcholine (DMPC; 4), as the outer layer on a monodispersed colloidal silica particle. The particle thus obtained was characterized by various physical measurements, such as FT-IR spectroscopy, transmission electron microscopy, differential scanning calorimetry, and zeta-potential measurements. These data strongly supported the successful formation of the asymmetric bilayer structure on the surface of the silica particle. The current method is widely applicable to various kinds of hybrids of inorganic particles with lipid membrane components.     

The adsorption, CMC determination and corrosion inhibition of some N-alkyl quaternary ammonium salts on carbon steel surface in 2 M H2SO4

Electrochemical measurements were performed to investigate the effectiveness of cationic surfactants of the N-alkyl quaternary ammonium salt type, i.e. myristyltrimethylammonium chloride (MTACl), cetyldimethylbenzylammonium chloride (CDBACl), and trioctylmethylammonium chloride (TOMACl), as corrosion inhibitors for type X4Cr13 ferritic stainless steel in 2 M H₂SO₄ solution. Potentiodynamic polarization measurements showed that these surfactants hinder both anodic and cathodic processes, i.e. act as mixed-type inhibitors. It was found that the adsorption of the N-alkyl ammonium ion in 2 M H₂SO₄ solution follows the Langmuir adsorption isotherm. Plots of log [θ/(1 − θ)] versus log c_inh yielded straight lines with a slope, which changed drastically at the critical micelle concentration (CMC) of the surfactants studied. Accordingly, the CMC could be accurately determined from these measurements. The calculated values of the free energy of adsorption ΔG_ads are, in cases when the charge on the metal surface is negative with respect to the PZC, relatively high what is characteristically for the chemisorption. On the other hand, for positive metal surfaces it is assumed that SO₄²⁻ anions are adsorbed first, so the cationic species would be limited by the surface concentration of anions. Accordingly ΔG_ads values were lower in this case and the adsorption is due to merely electrostatic attraction, which is characteristically of physisorption.     

Influence of charge density on the swelling of colloidal poly(N-isopropylacrylamide-co-acrylic acid) microgels

The volume phase transition of colloidal poly(N-isopropylacrylamide-co-acrylic acid) microgels depends in a complex way on the effective charge density within the polymer network. A series of monodisperse PNIPAM/AAc microgels with different content of acrylic acid were synthesized by surfactant-free emulsion polymerization employing sonication instead of a conventional stirring technique. Subsequently, the colloids were characterized by dynamic light scattering and electron microscopy. Potentiometric titrations provided the amount of carboxyl groups incorporated into the copolymer. The effective charge density was systematically controlled by the content of acrylic acid monomers, the pH value of the suspension, and the salt concentration. The hydrodynamic dimensions of the microgels have been measured by dynamic light scattering. The swelling/deswelling behavior is determined by the delicate balance between hydrophobic attraction of NIPAM and the repulsive electrostatic interactions of the carboxylate group of the acrylic acid moieties. Compared to their macroscopic counterparts the charged microgel particles show a significantly different swelling/deswelling behavior. This manifests in the occurrence of a two-step volume phase-transition process with increasing acrylic acid content. Hydrogen bonding has to be considered to understand this two step volume phase transition uniquely observed for colloidal microgels. Another interesting phenomenon presented here is the reversible formation of well-defined aggregates at low pH and under high salt conditions.     

Sodium carboxymethylcellulose-CTAB interaction: a detailed thermodynamic study of polymer-surfactant interaction with opposite charges

Interaction between polymer and surfactant bearing opposite charges is much more complex from a physicochemical point of view as compared to interaction between ionic surfactant and nonionic polymer. Electrostatic and hydrophobic interactions interplay in the former, whereas the hydrophobic effect is the prevailing factor in the latter. We have studied the interaction between a water-soluble polyanion, sodium salt of carboxymethylcellulose (NaCMC), with a cationic amphiphile, CTAB, in aqueous medium. There were manifold discrepancies with the reported works in NaCMC-alkyltrimethylammonium bromide, which is assumed to be an effect of difference in degree of substitution, which in turn affects the charge density of the polymer chain. We have noticed that the bulk complexation and interfacial interaction driven by electrostatic forces operate side by side. Thereafter, there is a wrapping process by the polyanion to the polymer-induced smaller surfactant aggregates driven by increase in entropy of the solution as a result of expulsion of the counterions from the ionic atmosphere around the surfactant aggregate. Because of the electrostatic interaction, hydrophobicity of the polymer-surfactant complex increases, leading to coacervation, and again solubilization in the hydrophobic core of the self-aggregated structure provided by the added excess CTAB. The tensiometric, conductometric, microcalorimetric, and turbidimetric techniques have been applied to address these problems.     

分子复合法制备新型聚合物驱油剂CMC/P(AM-DMDAAC)

通过具有互补结构的阴离子聚合物羧甲基纤维素(CMC)与阳离子聚合物聚(丙烯酰胺-二甲基二烯丙基氯化铵)[P(AM-DMDAAC)]间的聚电解质分子复合作用,制备了分子复合型CMC/P(AM-DMDAAC)新型驱油剂.电导率测定及紫外光谱分析结果表明,CMC与P(AM-DMDAAC)可以在水相通过库仑力形成均相聚电解质复合溶液.由于分子复合形成的独特超分子结构,复合溶液粘度显著增加,分别为组分聚合物溶液的5.2倍和9.0倍,在高温和高剪切环境中的粘度保持能力也明显优于其组分聚合物.     

Experimental study of a dynamic filtration system with overlapping ceramic membranes and non-permeating disks rotating at independent speeds

In a previous paper [Ding et al., J. Membr. Sci. 276 (2006) 232], we have investigated the performance in microfiltration of mineral suspensions of a novel filtration pilot consisting in overlapping ceramic membranes disks rotating at same speed on two parallel shafts. In this paper, we investigate a modification of this concept in which the ceramic disks of one shaft were replaced by non-permeating metal disks of same size rotating at a speed different from that of membranes. We also operated the pilot without disks on the 2nd shaft in order to eliminate membrane overlapping. When using metal disks with radial vanes, permeate fluxes were found to be 50–60% higher than those obtained in the same conditions with the previous design using only ceramic disks. By comparing permeate fluxes in different configurations, membranes on both shafts, membranes on the 1st shaft with and without metal disks on the 2nd shaft, we showed that, at a feed concentration of 200 g L⁻¹, the effect on permeate flux J, of shear rate increment due to membrane overlapping, could be completely offset by the high concentration increase between two adjacent and overlapping membranes. Raising the ceramic disks rotation speed N_c had a larger effect on J than increasing the metal disks speed N_m. For N_c = 32.16 Hz (1930 rpm) and N_m = 2.4 Hz (144 rpm), J reached 1790 L h⁻¹ m⁻² at 310 kPa, versus 1100 L h⁻¹ m⁻² for N_c = 12.3 Hz (738 rpm) and N_m = 22.26 Hz (1336 rpm) (for the same total sum N_c + N_m). Measurements of electrical power consumed by friction on rotating disks showed that the energy spent per m³ of permeate was lowest when using metal disk with vanes rotating at low speed and ceramic disks rotating at high speed.     

含三苯基氧磷结构聚芳醚醚酮酮的合成与表征

以苯酚、对二溴苯及苯基磷酰二氯为原料合成出二(4-苯氧基苯基)苯基氧磷(BPOPPO)。 三氯化铝(AlCl₃)为催化剂,通过缩聚反应,BPOPPO与对苯二甲酰氯(TPC)反应制备出一种含有三苯基氧磷结构的聚醚醚酮酮(P-PEEKK)树脂。 采用傅里叶变换红外光谱仪(FT-IR)、差示扫描量热仪(DSC)、热重分析仪(TGA)和广角X射线衍射(WAXD)等技术手段对P-PEEKK树脂的结构和性能进行表征。 结果表明,P-PEEKK树脂属于非晶聚合物,玻璃化转变温度(T_g)较高,为190.5 ℃;热分解温度(T_5%)为515 ℃,耐热性能较好;极限氧指数(LOI)为42,阻燃性能好,为难燃材料;易溶解于氯仿、1,2-二氯乙烷、N,N-二甲基乙酰胺等有机溶剂中,溶解性能较好,便于涂膜加工;拉伸强度为62 MPa,力学性能较好。     

Rheological behavior in water of complexes formed from poly(sodium 2-(acrylamido)-2-methylpropanesulfonate) and positively charged rodlike micelles

The viscoelastic behavior of aqueous solutions of an ionic complex formed from poly(sodium 2-(acrylamido)-2-methylpropanesulfonate) and rodlike mixed micelles of dimethyloleylamine oxide (DMOAO) and hexadecyltrimethylammonium chloride (CTAC) was investigated under oscillatory conditions. The DMOAO/CTAC mixed micelles exhibited high zero-shear viscosities (eta0) depending on the mole fraction of CTAC in the mixed micelle (Y) in the range 0Y0.25. The addition of the polyanion had no effect on the rheological behavior of the mixed micelles when Y<0.02 at an ionic strength (mu) of 0.2. However, when Y was increased to a certain level (Yc), eta0 decreased drastically; Yc depended on mu but not on the polymer concentration. These observations indicate the formation of an ionic complex between the polymer and micelle when YYc. The reciprocal of steady-state compliance (Je(-1)) began to decrease gradually at Y approximately Yc and then leveled off at Y>0.06. The relaxation time (tau) was found to be more strongly dependent on Y. Thus, the large decrease in eta0 was attributed mainly to a decrease in tau while the number density of junctions decreased only slightly. Therefore, it is concluded that polymer-micelle complex maintains a rodlike structure with some entanglements remaining at Y<0.12.     

Stable colloidal dispersions of a lipase-perfluoropolyether complex in liquid and supercritical carbon dioxide

The technique of hydrophobic ion pairing was used to solubilize the lipase from Candida rugosa in a fluorinated solvent, perfluoromethylcyclohexane (PFMC), in complex with a perfluoropolyether (PFPE) surfactant, KDP 4606. The enzyme-surfactant complex was determined to have a hydrodynamic diameter of 6.5 nm at atmospheric pressure by dynamic light scattering (DLS), indicating that a single lipase molecule is stabilized by surrounding surfactant molecules. The complex formed a highly stable colloidal dispersion in both liquid and supercritical carbon dioxide at high CO2 densities (>0.92 and 0.847 g/mL, respectively), with 4% by volume PFMC as a cosolvent, yielding a fluid that was orange, optically translucent, and very nearly transparent. DLS demonstrated aggregation of the enzyme-surfactant complexes in CO2 at 25 and 40 degrees C and various pressures (2000-5000 psia) with hydrodynamic diameters ranging from 50 to 200 nm. The mechanism by which the enzyme-surfactant particles aggregate was shown to be via condensation due to very low polydispersities as characterized by the size distribution moments. Interparticle interactions were investigated with respect to density and temperature, and it was shown that on decreasing the CO2 density, the particle size increased, and the stability against settling decreased. Particle size also decreased as the temperature was increased to 40 degrees C, at constant CO2 density. Nanoparticle aggregates of an enzyme-surfactant complex in CO2, which are nearly optically transparent and stable to settling, are a promising new alternative to previous types of dispersions of proteins in CO2 that either required water/CO2 microemulsions or were composed of large particles unstable to settling.     

Specific features of tetranitrotetrazolium blue chloride as an extraction reagent for iron(III)

A liquid-liquid extraction-chromogenic system containing Fe(III), 4-(2-thiazolylazo)resorcinol (TAR), [3,3’-(3,3’-dimetoxy-4,4’-biphenylene)bis[2,5-di(4-nitrophenyl)-2H-tetrazolium] chloride (tetranitro-tetrazolium blue chloride, TNBT), water, and chloroform was studied and compared with similar systems containing such ditetrazolium salts (DTS), as neotetrazolium chloride (NTC), blue tetrazolium chloride, and nitro blue tetrazolium chloride. The results show that the complex formed in the Fe(III)–TAR–TNBT system is of different composition (1 : 3 : 2 vs. 1 : 2 : 1) and has better extraction-spectrophotometric characteristics (fraction extracted is 98.6 % and molar absorptivity, 7.8 × 10⁴ dm³ mol^–1 cm^–1 at λ = 495 nm). The proposed formula of the complex is (TNBT⁺)[Fe^III(TAR^2–)₂]·{(TNBT⁺)(HTAR^–)}, where TNBT is in the monocationic form. The geometry optimization for TNBT and NTC–the DTS, which does not contain nitro- and methoxy groups, was performed by the Restricted Hartree–Fock (RHF) method with the 3-21G* basis set. The obtained results (ground-state structures and total atomic charges) for TNBT, TNBT⁺, TNBT²⁺, NTC, and NT²⁺ were compared and discussed.     

Electrochemical masking of large amounts of copper in dpasv and the determination of thallium in the presence of a large excess of copper

The influence of the following surfactants on the peak of copper in 0.2M EDTA at pH 4.5 was investigated: polyoxyethylated alkylphenols having an average of 3 and 9.5 ethylene oxide units; polyoxyethylene alcohols having 4 and 7 ethylene oxide units; poly(ethylene glycols) having M.W. 4000, 9000 and 20000; hexadecyltributylphosphonium bromide (HDTBPB), tetraphenylphosphonium bromide (TPPB),N,N,N,N,N',N',N-examethylhexamethylenediammonium bromide (HMB), benzyl(di-isobutylphenoxyethoxy) dimethylammonium chloride (Hyamine 1622), hexadecyltrimethylammonium bromide (HDTMAB), hexadecyldimethylbenzylammonium chloride (HDDMBAC) and tetrabutylammonium chloride (TBAC). HDDMBAC, as well as all the substances examined which contained an ethylene oxide chain, completely suppressed the copper peak. HDTBPB and TPPB partially suppressed the peak, whereas HDTMAB, HMB and Hyamine 1622 enhanced it. TBAC was without effect. In 0.2M EDTA at pH 4.5 containing TBAC at 0.01M concentration and 10 ppm of Rokafenol N-3, Cu(II), Pb(II) and Bi(III) can be tolerated at concentrations of up to 0.05M, the height of the thallium peak being unaffected. The precision of the determination (3–10%) and the recovery are satisfactory. A 10³-fold ratio of Fe(III) to Tl(I) does not interfere with the determination.     

Swelling of N-isopropyl acrylamide hydrogels in aqueous solutions of sodium chloride

Hydrogels are three-dimensional networks of hydrophilic polymer chains. Hydrogels can absorb/desorb water and hydrophilic solutes. This behavior is called swelling/shrinking, as it is accompanied by a volume change. The amounts of absorbed substances depend on the structure of the hydrogel and the composition of the coexisting liquid phase. This paper deals with experimental investigations of the swelling behavior of nonionic, chemically crosslinked, synthetic hydrogels of N-isopropyl acrylamide. The swelling equilibrium of some hydrogels in aqueous solutions of sodium chloride was investigated at 298 K. The experimental results are presented, discussed and correlated/predicted with a thermodynamic model which combines an expression for the Gibbs energy of a liquid phase with an expression for the Helmholtz energy of an elastic network.     

Metallomicellar catalysis: effects of bridge-connecting ligands on the hydrolysis of PNPP catalyzed by Cu(II) complexes of ethoxyl-diamine ligands in micellar solution

The syntheses of three ligands are reported: N,N,N′,N′-tetra(2-hydroxyethyl)-1,3-propylene-diamine (1), N,N,N′,N′-tetra(2-hydroxyethyl)-1,10-decadiamine (2), N,N,N′,N′-tetra(2-hydroxyethyl)-1,4-xylyldiamine (3). The catalytic hydrolysis of p-nitrophenyl picolinate (PNPP) by the bivalent metal ion Cu(II) complexes of these ligands was studied kinetically in a buffered CTAB or Brij35 micellar solutions at 25 °C and different pH values. The results indicate that 1:2 and 2:1 complexes of these ligands and metal ion are the active species for the catalytic hydrolysis of PNPP in CATB and Brij35 micellar solutions. The ternary complex kinetic model for metallomicellar catalysis was employed to obtain the relative kinetic and thermodynamic parameters. The effects of the structure of the ligands and the microenvironment of reaction on the hydrolytic reaction of PNPP have been discussed in detail.