Interpolymer complexes of copolymers of vinyl ether of diethylene glycol with poly(acrylic acid)

 The complex formation reactions of poly(vinyl ether of diethylene glycol) as well as vinyl ether of diethylene glycol–vinyl butyl ether copolymers with poly(acrylic acid) have been studied in aqueous and alcohol solutions. The formation of interpolymer complexes which were stabilized by hydrogen bonds was shown. The effects of molecular weight of poly(acrylic acid) and the nature of the nonionic polymer on the composition and stability of interpolymer complexes were clarified. The critical pH values of complexation were determined for different systems with various molecular weights and hydrophobic–hydrophilic balances. The stability of the interpolymer complexes formed in aqueous and alcohol solutions with respect to dimethylformamide addition was evaluated. The role of hydrophobic interactions and the presence of active groups on stability of the interpolymer complexes is discussed. Received: 23 July 2001 Accepted: 27 September 2001     

Interpolymer complexes of poly(acrylic acid) with poly(2-hydroxyethyl acrylate) in aqueous solutions

Complexes formed from poly(acrylic acid) and poly(2-hydroxyethyl acrylate) were studied in aqueous solutions by viscometric, turbidimetric, FTIR spectroscopic, and thermogravimetric analysis methods. The formation of interpolymer complexes stabilized by hydrogen bonds was observed. It was found that the compositions of these interpolymer complexes are strongly dependent on the concentration of polymers, the order of mixing the solutions, and the pH. It was demonstrated that the complexation ability of poly(2-hydroxyethyl acrylate) is relatively low compared to other known nonionic water-soluble polymers. However, it can be significantly increased via hydrophobic modification of the poly(acrylic acid) using cetyl pyridinium bromide.     

Catalysis of heteropoly acidic salts for synthesis of diethylene glycol ethyl ether with diethylene glycol and ethanol

Ag₃PW₁₂O₄₀ and Ag₄SiW₁₂O₄₀ showed high activity and stability in the synthesis of diethylene glycol ethyl ether with diethylene glycol and ethanol, on which the conversion is 80.2% and 78.4%, respectively, and the selectivity of diethylene glycol ether is 75.4% and 80.6%, respectively. After the third reaction cycle, Ag₃PW₁₂O₄₀ and Ag₄SiW₁₂O₄₀) still showed higher activity and selectivity, on which the conversion is 72. 6% and 77.5% respectively. But the activity of Ag₃PMo₁₂O₄₀ is lower, the conversion is only 21.0%. IR, XRD, TG and n‐butylamine titrimetry showed that the catalysis may be connected with two kinds of acidic centers owned by heteropoly acidic salt.     

pH-effects in the complex formation of polymers I. Interaction of poly(acrylic acid) with poly(acrylamide)

The effects of polymer concentration, molecular weight of poly(acrylic acid) (PAA), addition of sodium, potassium, ammonium and copper (II) chlorides on the complex formation ability of the system PAA-poly(acrylamide) (PAAM) have been studied in aqueous solutions. The critical pH values of the complexation were determined in different conditions. The complex formation ability of PAAM is compared with other non-ionic polymers. It was shown that an increase in polymers concentration, molecular weight of PAA and ionic strength favours the complexation and shifts the critical pH values to the higher pH region. An addition of CuCl₂ to the mixture of two polymers enhances the complexation drastically due to the formation of triple complexes.     

Hollow capsules formed in a single stage via interfacial hydrogen-bonded complexation of methylcellulose with poly(acrylic acid) and tannic acid

Hollow capsules can be prepared in a single stage by the interfacial complexation of methylcellulose (MC) with poly(acrylic acid) (PAA) or tannic acid (TA) via hydrogen bonding in aqueous solutions. The formation of capsules is observed when viscous solution of methylcellulose is added drop-wise to diluted solutions of polyacids under acidic conditions. The optimal parameters such as polymer concentration and solution pH for the formation of these capsules were established in this work. It was found that tannic acid forms capsules in a broader range of concentrations and pHs compared to poly(acrylic acid). The TA/MC capsules exhibited better stability compared to PAA/MC in response to increase in pH: the dissolution of TA/MC capsules observed at pH > 9.5; whereas PAA/MC capsules dissolved at pH > 3.8. The interfacial complexation can be considered as a potential single stage alternative to the formation of capsules using multistage layer-by-layer deposition method.     

Interaction between pentaethylene glycol n-octyl ether and poly(acrylic acid): effect of the polymer molecular weight

The effect of the polymer molecular weight on the interaction between pentaethylene glycol n-octyl ether (C(8)E(5)) and poly(acrylic acid) (PAA) has been investigated by a combined experimental strategy including tensiometry, potentiometry, calorimetry, fluorescence quenching and intradiffusion (pulsed gradient spin echo-NMR) measurements. PAA samples with an average molecular weight varying in a wide range (M (w)=2000, 100,000, 250,000, and 450,000) have been considered. The measurements have been performed at constant polymer concentration (0.1% w/w) with varying surfactant molality. In all the considered systems, at low surfactant concentration, adsorption of surfactant monomers onto the polymer chain has been detected. At a C(8)E(5) molality (T(1)) independent of the PAA M (w), surfactant molecules start to aggregate, forming clusters to which the polymer co-participates. Above this concentration, the behavior of the system depends on M (w). In fact, if polymer samples with high molecular weight (M (w)100,000) are employed, all the added surfactant aggregates onto the polymer leading to the polymer saturation and, subsequently, to free micelles formation. Both saturation and free micellization occur at surfactant concentrations which are independent of the polymer molecular weight. C(8)E(5) aqueous mixtures containing PAA with low molecular weight (M (w)=2000) behaves differently, in that, above T(1), only a fraction ( approximately 20%) of the added surfactant molecules interact with the polymer, forming aggregates to which more than one PAA chain participate. In this case, C(8)E(5) free micellization occurs before polymer saturation. The experimental evidences have been interpreted in terms of the subtle balance between the various molecular interactions driving the surfactant-polymer aggregation.     

Solid-State coextrusion of high-density polyethylene. II. Effect of molecular weight and molecular weight distribution

The recently developed technique of solid-state coextrusion for ultradrawing semicrystalline thermoplastics has been applied in the preparation of self-reinforced high-density polyethylene extrudates. The extrudates consist of definite core and sheath phases composed of different molecular weights (M_w) in the range of 60,000–250,000 and different molecular weight distributions (M_w/M_n = 3.0–20). Concentric billets of two different phases were prepared for extrusion by in serting a polyethylene rod within a tubular billet of a different high-density polyethylene followed by melting the two phases to obtain bonding between them. The billet was then split longitudinally to increase extrusion speed and extruded at 120°C, 0.23 GPa through a conical die of extrusion draw ratio 25. Extrudates of high tensile modulus (38 GPa) and strength (0.50 GPa) could be produced in a steady state process at a rate near 0.25 cm/min. The tensile properties of the extrudates from either the single or concentric billets increased with average molecular weight and were insensitive to the molecular weight distribution of the constituent phases. Thermal analysis indicated a high deformation efficiency for the sheath and core phases of the extrudates by the coextrusion technique.     

Polymeric Nitrofuran Derivatives. II. Chemical Modification of Functionalized Resins with Nitrofuran Derivatives

Polymeric nitrofuran derivatives have been synthesized by chemical modification of macroporous styrene-divinylbenzene copolymers with low molecular weight nitrofurans. The 5-nitrofuryl groups are covalently attached to the polymeric carrier by azomethine, ester, N-alkyl, and sulfamide links, respectively. Comparative hydrolysis studies and biological tests of the modified resins suggested that the polymeric carrier-bound nitrofurans are antimicrobially active. The polymeric nitrofurans have been characterized by IR and “C-solid-NMR spectroscopy”.     

Synthesis and Characterization of Nickel(II) Complex Containing 2‐(t‐Butylaminomethyl)pyrrole

Two aminopyrroles, 2‐(t‐butylaminomethyl)pyrrole ( HL1 ) and 2, 5‐di(t‐butylaminomethyl)pyrrole ( HL2 ), were synthesized and the hydrogen‐bond interactions were observed in the single‐crystal X‐ray structures of HL1 ·HCl and HL2. Bis[2‐(t‐butylaminomethyl)pyrrole]nickel( II ) [ Ni(L1) ₂] was prepared by treatment of the NiCl₂ with 2 equiv. of mono‐deprotonated HL1 in THF solvent. The solid‐state structure of Ni(L1) ₂ shows the N₄‐coordinated nickel atom, with a geometry corresponding to a square‐planar structure, in which two intramolecular C‐H···Ni interactions are present at the axial positions with contact distances of 2.77 Å. The complex displays an irreversible reduction response at ?0.66 V (vs. Fc⁺/Fc) in CH₃CN. Furthermore, ¹H, ¹³C‐HSQC NMR experiments performed at room temperature revealed that the two methylene protons of the chelating L1^?1 are chemically nonequivalent and one of them is coupled to the amino proton. The coupling constants (J_HH') observed are close to the values predicted from the vicinal Karplus correlation diagram.     

-B(OH)2 versus -OH in supramolecular synthesis: molecular complexes of 4-hydroxyphenylboronic acid with aza-donor compounds

-B(OH)₂ moiety forms interactions with aza-donor compounds as much as -OH does, as derived from the supramolecular assemblies of 4-hydroxyphenylboronic acid with aza-donor compounds demonstrating for the first time, a comparative study of -B(OH)₂ versus -OH.     

Synthesis and crystal structures of Cd(II), Ni(II), and Mn(II) complexes of 1H-benzotriazole-1-acetic acid

Three new complexes: [Cd(btaa)(bipy)(CH₃COO) · H₂O] _n (1), [Ni(btaa)₂(H₂O)₄ · 6H₂O] _n (2), and [Mn(btaa)₂(H₂O)₂] _n (3) (bipy = 2,2′-bipyridine, Hbtaa = 1H-benzotriazole-1-acetic acid) were prepared and characterized by IR, elemental analyses, thermogravimetric analyses, and single-crystal X-ray analyses. In 1, cadmium ions are linked by btaa ligands into 1-D linear chains; the chains are extended into layers through C–H ··· O hydrogen bonds and π–π stacking interactions. Complex 2 is a mononuclear structure, extended to a 3-D network through multiple intermolecular hydrogen bonds. In 3, manganese is bridged by carboxylate groups of btaa in the syn–skew bidentate mode in two directions to form a 2-D grid-like framework with a (4, 4) topology. The solid-state fluorescence spectrum of 1 shows that the excitation peak is at 355 nm while the maximum emission peak is at 424 nm.     

Swelling behavior of amphiphilic hydrogels of copolymers of the vinyl ether of ethylene glycol and vinyl isobutyl ether,and their interaction with cationic surfactant

Amphiphilic hydrogels of copolymers of the vinyl ether of ethylene glycol and vinyl isobutyl ether were synthesized by -radiation-induced free radical polymerization. Hydrogels with certain copolymer compositions showed thermo-sensitive behavior in aqueous solutions. The swelling behavior of the hydrogels in cetylpyridinium bromide aqueous solution was studied. Increased swelling of the hydrogels was observed in the surfactant solutions. The increased swelling was more prominent for the hydrogels with a higher content of hydrophobic moiety in the copolymer composition, and with higher surfactant concentration. The reason for this phenomenon is discussed. Treatment of some hydrogels in the surfactant solutions resulted in higher swelling ability in distilled water with distinct thermo-induced contraction over a narrow temperature interval.     

Synthesis and characterization of three ionic pairs of Fe(II) and Co(II) complexes with tridentate salicylideneglycine

Three new transition metal complexes, [Fe^II(H₂O)₆][(C₉H₇NO₃)₂Fe^II] · H₂O (1), H[K(H₂O)₃][(C₉H₇NO₃)₂Co^II] · H₂O (2), and [Co^II(H₂O)₆][(C₉H₇NO₃)₂Co^II] · H₂O (3), with salicylideneglycine have been synthesized and characterized by elemental analysis, IR spectra, UV-Vis spectroscopy, and X-ray crystallography. The structure analyses indicate that the tridentate salicylideneglycine binds through aliphatic nitrogen, phenoxy, and carboxylic oxygen in the anion. There are many inter- and intra-molecular hydrogen bonds among lattice water, the anion, and the cation to form a 3-D network. The thermogravimetric analyses and the quantum chemistry calculations of compounds 1, 2, and 3 are also discussed.     

Synthesis and Characterization of a Novel Binuclear Cobalt(II) Complex with Discrete Water Clusters (H2O)8

A new octameric water cluster was observed in the complex Co₂(dptc)(bipy)₂(H₂O)₆ · 4H₂O ( 1 ) (H₄dptc = diphenyl‐3,3′,4,4′‐tetracarboxylic acid; bipy = 2,2′‐bipyridine), which was characterized by single‐crystal X‐ray diffraction, elemental analysis and IR spectroscopy. The centrosymmetric octamer consists of a water hexamer in the chair form and two water molecules and brings to light a novel mode of the cooperative association of water molecules. Those complex units are connected into a 2D infinite layer framework through hydrogen bonding. Consequently, the 2D layers are further aggregated by hydrogen bonding with octameric subunits and π ··· π stacking interactions to form a 3D supramolecular architecture.     

Ternary complexes in solution: Complex formation between copper(II), zinc(II), cadmium(II) and ligands of biological importance

The stability constants of ternary complexes of theMAL type have been determined for Cu(II), Zn(II) and Cd(II). The ligands chosen for this study belong to the biologically important ones viz. Bipyridyl (A) and Nitrilotriacetic acid (L). LogK _MAL values for Cu(II), Zn(II) and Cd(II) are 11.42, 10.67 and 9.72, respectively, at temp.=25°C and =0.1M (KNO₃); the order is discussed.

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Ternäre Komplexe in Lösung: Die Komplexibildung zwischen Kupfer(II), Zink(II) und Kadmium(II) mit Liganden von biologischem Interesse

Zusammenfassung Die Stabilitätskonstanten für Cu(II)-, Zn(II)- und Cd(II)-Komplexe vom TypMAL wurden bestimmt. Die biologisch relevanten Liganden, die für diese Untersuchung ausgewählt wurden, waren Bipyridyl (A) und Nitrilotriessigsäure (L). Bei einer Temperatur von 25°C und =0,1M (KNO₃) sind die entsprechenden logK _MAL -Werte für Cu(II), Zn(II) und Cd(II) 11,42, 10,67 und 9,72; diese Reihenfolge wird ebenfalls diskutiert.

     

Interpolymer complex formation of some nonionogenic polymers with linear and crosslinked polyacrylic acid

The formation of interpolymer complexes on the surface of crosslinked poly (acrylic acid) with some nonionogenic polymers is compared with the complex formation in analogous linear polymer systems. The behavior of these systems is compared with that of complexes of two oppositely charged polyelectrolytes. The concentration redistribution of the linear polymer in the system polyelectrolyte network-polymer solution and the degree of swelling of this network in these solutions were determined. © 1994 John Wiley & Sons, Inc.     

Kinetics of poly(ethylene terephthalate) glycolysis by diethylene glycol. Part II: Effect of temperature, catalyst and polymer morphology

The influence of various parameters on the kinetics of poly(ethylene terephthalate) (PET) glycolysis by diethylene glycol (DEG), namely temperature (from 190 to 220 °C), temperature profile, catalysis and PET morphology has been studied.The results showed a strong influence of some experimental conditions (temperature and catalysis) on the mixture evolution during depolymerisation. The temperature study showed a critical temperature between 210 and 220 °C which seems to be the consequence of a better diffusion of DEG in PET, allowing easier reactions in solid phase. The initial morphology of PET scraps does not affect the rates of reactions much, in contrast to the temperature profile which has a great importance: time of PET dissolution at 220 °C is considerably shorter by heating PET and DEG separately at 220 °C before mixing, than by heating a cold mixture of the two reagents to 220 °C.     

The effect of molecular weight on the crystallization kinetics and equilibrium melting temperature of poly(tetramethylene ether glycol)

Isothermal crystallization of poly(tetramethylene ether glycol) (PTMEG) with relatively low molecular weight (M_n = 991, 2004 and 2864, respectively) was investigated by differential scanning calorimetry, and the equilibrium melting temperature (T) determined using the Hoffman–Weeks analysis. The crystallization kinetics of PTMEG were characterized using an Avrami analysis. Mechanistic n values ranged from 2.2 to 2.9 for the primary crystallization process for three molecular weight grades, indicating heterogeneous nucleation of spherulites. Polarized light microscopy confirmed that PTMEG crystallized by the growth of spherulites from heterogeneous nuclei. The half–life for crystallization (t_1/2) and the composite rate constant were found to be dependent on the degree of supercooling (ΔT) and the molecular weight. Copyright © 2006 John Wiley & Sons, Ltd.     

Polyurethane anionomers synthesised with aromatic, aliphatic or cycloaliphatic diisocyanates, polyoxyethylene glycol and 2,2-bis-(hydroxymethyl)propionic acid. Part II. Supermolecular structure. Thermal properties

Small angle X-ray scattering and differential scanning calorimetry methods were employed to characterise the internal order of structural phases present in polyurethane coatings obtained as a result of water evaporation from anionomer dispersions. Those anionomers were produced in the reaction of aromatic, cycloaliphatic and aliphatic diisocyanates with polyoxyethylene glycol, 2,2-bis-(hydroxymethyl)propionic acid and 1,6-hexamethylenediamine. The decisive effects were found from ionic and polar structures within the rigid urethane and urea segments on the ordered arrangement degree of the supermolecular structures in the obtained anionomers. That becomes apparent in differential scanning calorimetry thermograms and contributes to improved thermal stability of the produced polyurethane coatings.