Complex Formation Of Poly Research Articles

Collapse of Poly(methacrylic acid) Hydrogels in Response to Simultaneous Stimulation by an Electric Field and Complex Formation

Complex formation of poly(methacrylic acid) hydrogels with linear poly(ethylene glycol) has been studied at different pH values and in the presence of an electric field. The fastest contraction of the gel sample was observed under simultaneous action of electric field and complex formation.

Water-absorbing properties of hydrogels based on polymeric complexes

Colloidal and chemical properties of polymeric complexes based on polyacrylamide and polyvinyl alcohol have been investigated. Several factors affecting water absorption by polymeric complexes have been studied: concentration of initial aqueous polymer solutions; components ratio in the mixture; temperature and duration; sorbed aqueous solutions properties (pH; kind of ions).Macromolecular globules of polyacrylamide in aqueous solutions upon addition of polyvinyl alcohol exhibit interactions of hydroxyl and amide groups. The heat treatment of polycomplexes aqueous solutions leads to formation of cross-linked products (hydrogels) which are not soluble in water and show superabsorbents properties.Variation of conditions of polycomplex formation allows to regulate the properties of the resulting products such as hydrogel strength and the water absorption in wide ranges. This gives us possibilities for optimal use of the hydrogels in function of their specific applications.

Molecular recognition in radical template polymerization

In our previous study, when mixing polymer solutions in a common solvent, we have found the existence of a molecular recognition effect with regard to the chain length in the polycomplex formation. In the present work, we found a similar phenomenon to occur in template polymerization with regard to the template polymer. The system studied was template polymerization of methacrylic acid (MAA) on poly(N-vinylpyrrolidone) (PVP) or on poly(2-dimethylaminoethyl methacrylate) (PDMAEM). The polymerization, carried out in ethanol or in tetrahydrofuran was initiated with AIBN. A series of copolymerizations of methacrylic acid and methyl methacrylate on PDMAEM was performed under similar conditions. Changes in molecular weight distribution of PVP and PDMAE templates in the course of polymerization and copolymerization were studied by gel permeation chromatography. A method was elaborated which permitted simultaneous determination of MWD of the uncomplexed fraction of the template, the extent of polymerization of monomers, and the composition of the polycomplex formed. The recognition effect with regard to the chain length of the template was also observed in homopolymerization of MAA as well as in copolymerization of MAA with methyl methacrylate (MMA). The results obtained are discussed with regard to the composition of the complexes formed and to the template – daughter polymer interaction. There was no effect of the solvent used.

Interpolymer complexes of poly(vinyl ether) of ethylene glycol with poly(carboxylic acids) in aqueous, alcohol and mixed solutions

The effect of polymer concentrations, pH, nature and molecular weight of polyacid and nature of solvent on the complex formation of poly(carboxylic acids) with poly(vinyl ether) of ethylene glycol has been studied. The role of hydrophobic interactions and ionization of polyacid in the stabilization of interpolymer complexes in aqueous solutions has been clarified. It has been shown that an increase of polymer concentrations and the hydrophobicity of polyacid shifts the critical pH values to the higher region. The competition between polymer–solvent and polymer–polymer interactions governs the complex formation processes.

Complex Formation of Poly(ε-caprolactone) with Cyclodextrins

Cyclodextrins (CDs) have been found to form inclusion complexes with poly(ε-caprolactone) (PEC) to give crystalline compounds. α- and γ-CD formed complexes with these polyesters in high yields, although β-CD gave complexes in moderate yields. The yields of the complexes decreased with increasing molecular weight of the polymer. α-CD−PEC complexes are stoichiometric one-to-one (cyclodextrin:monomer unit) compounds, and γ-CD−PEC complexes are one-to-two compounds when the molecular weights of PEC are low. The complexes were isolated and characterized by 1H NMR, 13C CP/MAS NMR, and X-ray diffraction studies. The inclusion modes are discussed.

Investigation of complex formation between poly(N-vinyl imidazole) and various metal ions using the molar ratio method

The complex formation of poly(N-vinyl imidazole) (PVIm) with various metal ions was studied. UV-vis spectroscopy was employed to study the interaction of PVIm and metal ions in aqueous solution. Formation constants of PVIm-metal complexes were calculated by applying a “mole ratio” method. The stoichiometric ratios between polymer and metal ions were found to be␣4. The stability constants for the complexes of PVIm with bivalent transition metal ions were in agreement with the Irving-William series. The biggest formation constant was found for the PVIm-Cu2+ complex system.

Water-soluble polyion complex associates of DNA and poly(ethylene glycol)-poly(L-lysine) block copolymer.

Complex formation of poly(ethylene glycol)-poly(L-lysine) (PEG-PLL) AB type block copolymer with salmon testes DNA or Col E1 plasmid DNA in aqueous milieu was studied. The PLL segment of PEG-PLL interacts with nucleic acid through an electrostatic force to form a water-soluble complex associate with a diameter of ca. 50 nm. PEG segments surrounding the core of the polyion complex prevented the complex from precipitation even under stoichiometric conditions, at which the unit ratio of L-lysine in PEG-PLL and phosphate in the DNA is equal. The profile of the thermal melting curve revealed a higher stabilization of DNA structure in PEG-PLL/DNA complexes compared to that in the complex made from DNA and PLL homopolymer with the same molecular weight as the PLL segment in PEG-PLL. This stabilizing effect on the DNA structure may be due to the compartmentalization of DNA into the microenvironment of PEG with low permittivity. The reversible nature of the PEG-PLL/DNA complex was further verified through the addition of polyanion [poly-(L-aspartic acid)]: Poly(L-aspartic acid) replaced DNA in the complex with PEG-PLL, resulting in the release of free DNA in the medium. Furthermore, the PEG-PLL/DNA complex showed high resistance against DNase I attack, suggesting DNA protection through the segregation into the core of the associate having PEG palisade.

Complex formation of poly(ε‐caprolactone) with cyclodextrin

AbstractPoly(ε‐caprolactone) was found to form inclusion complexes with α‐cyclodextrin to give crystalline compounds. The complexes are stoichiometric one‐to‐one (cyclodextrin: monomer unit) compounds. The yields of the complexes decreased with increasing the molecular weight of the polymer. They were characterized by IR, 1H NMR, 13C CP/MAS NMR, and X‐ray diffraction. The inclusion modes are discussed.

Interpolymer complexes. Properties and characterization

AbstractInterpolymer complex formation between poly(N‐vinyl‐2‐pyrrolidone) (PVP) and poly(monomethyl itaconate) (PMMel) has been studied. Data from Dynamic Light Scattering show at least two different size distributions of polymer complex (PC). The PC size distributions increase when the temperature increases. Viscosity measurements were also performed in order to estimate the polycomplex segmental density. From these results it can be concluded that PVP and PMMel give rise to a polycomplex formation and the driving force for this association is hydrogen bonding as much as hydrophobic interactions.

Solutions spinning of the high Tc oxide superconductor. II. Effect of organic acid on the complex formation of PVA with the copper (II) ion

AbstractAs basic research for the solution spinning of the high Tc oxide superconductor, the effect of organic acid on the complex formation of poly(vinyl alcohol) (PVA) with the copper [Cu(11)] ion was explored with various carboxylic acids, such as formic acid, acetic acid, n‐butylic acid, and lactic acid. The effects of these acids on the interaction between PVA and Cu(II) acetate in aqueous solution were nonexistent, while a chelation of the Cu(II) ion and lactic acid was detected. In the solid state, a linear complex of PVA with the Cu(II) ion was formed by adding organic acid. The ligand of the linear complex was highly dependent on the kind of acid used. © 1994 John Wiley & Sons, Inc.

Complex Formation of Poly(acrylic acid) with Mg, Mn, and Pb Ions in Dioxane-Water Mixed Solvents

Abstract Equilibria between poly(acrylic acid) and Mg(II), Mn(II) and Pb(II) ions have been investigated at 25 °C by means of potentiometric and viscometric titrations in dioxane-water mixed solvents containing 0.1 mol dm−3 added salt to maintain a constant ionic strength. The stability constant for the complex formation reaction, M2+ + iA− = MAi2−i, and the equilibrium constant for the reaction, M2+ + iHA = MAi2−i + nH+ (HA denotes a carboxyl group) have been evaluated from the data of pH titration. Although the stability constants, β1 and β2, increased with dioxane content in the mixed solvent and depended on the kinds of added salts, the equilibrium constants, B1 and B2, were almost independent of both factors. The values of B1 for Mg, Mn, and Pb monocarboxylate complexes were 10−3.1, 10−2.5, and 10−1.0 and those of B2 for Mg, Mn, and Pb dicarboxylate complexes were 10−7.6, 10−5.7 and 10−2.1, respectively. From the data of viscometric titrations of poly(acrylic acid) solutions containing Pb(II) ion, it is considered that the contraction of polymer coil is caused by the intramolecular complex formation with two remote carboxylate groups in the range of low degree of neutralization (α′). As α′ increases, the complex is transformed into another form which consists of two adjacent carboxylate groups.

Complex Formation of Poly(Acrylic Acid) with Lead(II) Ion

Abstract The equilibrium constants of Poly(acrylic acid)–Pb(II) complex formation reactions were evaluated from stoichiometric equations by means of pH titration with a Pb(II) ion selective electrode. The thermodynamic parameters were obtained from the temperature dependence of the equilibrium constants. The Poly(acrylic acid)–Pb(II) complexes seem to be stable due to an exothermic process.

Complex Formation and Ionic Association in Methanol Solutions of Poly(Ethylene Oxide) and Alkaline Earth Salts

Abstract Complex formation of poly(ethylene oxide) (PEO) with divalent barium and strontium salts was investigated in methanol. In these systems the complexation was accompanied by a considerable degree of ionic association. An analytical model for the polymer-ion complexation based on a one-dimensional lattice model was proposed. According to this model, the electrostatic effects between the bound ions were separated from the total free energy change of the binding. Three binding constants, i.e., the ionic association constant K A, the cation binding constant, K c, and the anion binding constant, K a, could be estimated. K A for barium and strontium salts was comparable, and the effect of counteranions on K A was not large. K c for barium salts was almost independent of the kind of counteranion and larger than that for corresponding strontium salts, indicating stronger polymer-ion interaction for barium salts. The anion binding constant, K a, was strongly dependent upon the kind of anion, and the order w...

Complex Formation of Poly(4-vinylpyridine) with Copper(II) Ion in Mixed Solvent

Complex formation of poly(4-vinylpyridine) with Cu(II) ion in a mixed solvent (water–methanol) was investigated potentiometrically, viscometrically, and spectroscopically. Poly(4-vinylpyridinium chloride) was observed to undergo a pH-induced conformational transition. Adding neutral salt caused a reduction in electrostatic repulsion among charges on the polymer chain. The stability of compact form was low, due to hydrophobic interactions among stacked pyridine rings. The maximum average coordination number was nearly three, in spite of the bulky ligand. The polymer chain was constricted by intramolecular complex formation since no charge exists on the ligands. The polymer–metal complex formation was not a stepwise reaction, but a one-step cooperative reaction resulting from the chelate effect of polymer ligands. Formation of an intramoleculer complex for each Cu(II) ion required nine or ten ligand units on the polymer chain, owing to the rigidity of polymer chain and the steric hindrance of bulky pyridine rings.

Complex formation of poly(ethylene glycol) with alkali metal and ammonium thiocyanates

By the methods of IR, Raman, 13C, 23Na and 7Li spectroscopy, wide-angle X-ray scattering and viscosimetry, the interaction of PEG of various molecular mass with alkali metal and ammonium thiocyanates was investigated. The effect of cation nature and size on the complex forming reaction was established. The role of the rhodanide anion in the formation of molecular complexes is discussed.

Two binding modes of netropsin are involved in the complex formation with poly(dA-dT).poly(dA-dT) and other alternating DNA duplex polymers.

Using CD measurements we show that the interaction of netropsin to poly(dA-dT).poly(dA-dT) involves two binding modes at low ionic strength. The first and second binding modes are distinguished by a defined shift of the CD maximum and the presence of characteristic isodichroic points in the long wavelength range from 313 nm to 325 nm. The first binding mode is independent of ionic strength and is primarily determined by specific interaction to dA.dT base pairs. Employing a netropsin derivative and different salt conditions it is demonstrated that ionic contacts are essential for the second binding mode. Other alternating duplexes and natural DNA also exhibit more or less a second step in the interaction with netropsin observable at high ratio of ligand per nucleotide. The second binding mode is absent for poly(dA).poly(dT). The presence of a two-step binding mechanism is also demonstrated in the complex formation of poly(dA-dT).poly(dA-dT) with the distamycin analog consisting of pentamethylpyrrolecarboxamide. While the binding mode I of netropsin is identical with its localization in the minor groove, for binding mode II we consider two alternative interpretations.

誘起円偏光二色性によるポリリシン同族体とメチルオレンジ間の相互作用における温度の効果の研究

誘起円偏光二色性によるポリリシン同族体とメチルオレンジ間の相互作用における温度の効果の研究

Formation of the poly(L-lysine) complex with pectin of various esterification degree

The circular dichroic (CD) measurement was chosen the tool to investigate the complex formation of poly(L-lysine) with potassium pectate or pectinate of various esterification degree (E). The polycation-polyanion (pectate, E 0%) 1 : 1 complex was quantitatively formed by an electrostatic interaction independently upon the excess of either component. The partial esterification of pectin resulted in a decrease of complex formation; this drop is at a 20% esterification degree low, at higher esterification degrees (46% and 64%) considerable, and at an esterification degree 86% the complex has not been formed at all. The polypeptide chain was present in the complex in an α-helical arrangement characterized by the CD spectrum; the potential spatial arrangements of the complex were proposed. The α-helical polypeptide component constitutes a core surrounded by a superstructure of D-galacturonan chains.

Thermochemical reactions in polycomplexes

Polycomplex formation between poly(methacrylic acid) and polyacrylamide in aqueous solutions has been studied by means of viscometry, potentionetry and elemental analysis. Stoichiometry of the polycomplex was found to be 1:1 with respect to unit-moles. I.R.-spectroscopic data give evidence of the co-existence of ladder-like regions and loops in the polycomplexes formed by poly(methacrylic acid) with polyacrylamide and poly(ethylene glycol). The reactivities of the same functional groups in ladder-like regions and loops are different. This difference has been shown taking as an example thermochemical reactions in the above polycomplexes. Dehydrocyclization in the poly(methacrylic acid) chain was found to occur in the loops of both polycomplexes. This intramolecular reaction in the polycomplex of poly(methacrylic acid) with polyacrylamide is followed by intermolecular formation of imide bonds in ladder-like regions.

Nmr studies on complex formation of poly(L‐lysine HBr) with carbonate ion in aqueous solution

AbstractDiemer formation of poly(L‐lysine HBr) in carbonate buffer at pD 10.5 was reported in our previous paper [Biopolymers(1981) 20, 345–357]. The mechanism of the dimer formation was investigated employing carbon‐13 and proton nmr. pD dependence of the 13C‐nmr spectrum of poly(L‐lysine HBr) in the presence of carbonate ion clearly shows that a complex formation between the CO ion and protonated ε‐amino group is involved in the stabilization of the dimer form. The lifetime of the complex is longer than 10−2 s. A stoichiometric evaluation suggests that CO bridges two lysyl side chains. A molecular model of the dimer form designated as a single antiparallel β‐ribbon was proposed and discussed in the light of hydrodynamic and ir spectroscopic properties reported earlier. Concentration change experiments indicate that CO binds not only to the dimer formation is inferred as stabilization of the single antiparallel β‐ribbon as an intermediate structure in the conversion between the α‐helix and β‐sheet. The α‐CH proton signal of the lysine residue located in the ordered structure (α‐helix and β‐form) was observed to be separate from that in the random‐coil region.