Polymer Complex Formation Research Articles

Chitosan-poly(acrylic acid): mechanism of complex formation and potential industrial applications.

The food industry is interested in polyelectrolytic coagulants of natural origin for the clarification of food beverages and the recovery of colloidal and dispersed particles from processing waste streams. This paper discusses potential industrial applications of recent findings on polymer complex formation obtained with a chitosan-poly(acrylic acid) model system. Process recommendations could be made on the basis of the ionic strength, pH, and charged group concentration of the fluid to be treated. Ionic strength does not affect the complex formation process. The amount of chitosan in the complex formed is controlled by the solution pH. The mechanism of complex formation indicates that pH measurements could be used to monitor the coagulation process.

Polymer complexes of arylacetylenes with iodine

The exothermal reaction of phenylacetylene with p-diethinylbenzene and iodine at 100–130°C, which results in the formation of polymer complexes, is shown to be related to the dehalopolycondensation of the products of addition of iodine to arylacetylenes formed during the initial stages of the process. The structure and some physicochemical properties of the polymer complexes are studied.

Functional Monomers and Polymers CLXXII. Synthesis and Interaction Studies on Water Soluble Nucleic Acid Analogs: Polyethyleneimine Derivatives Containing Thymine and Adenine

Nucleic acid analogs were prepared by grafting cytosine and hypoxanthine derivatives containing hydroxyl groups onto linear polyethyleneimine. The polymers contained about 90 unit mol% of the nucleic acid bases, and were easily soluble in water at neutral pH value. They were found to form polymer complexes with polynucleotides (PolyI and PolyC) by specific base-base interactions in aqueous solution.

Preparation and Complex Formation of Polymers Anchoring 2-Oxazolidinone

Abstract Polymers anchoring 3-unsubstituted 2-oxazolidinone were prepared and their complex formation with phenol and mercury(II) acetate were investigated. Preformed poly(4-hydroxystyrene) was treated with tris(2,3-epoxypropyl) isocyanurate to give a polymer containing 2-oxazolidinone residues within the limits of 57.7 mol%. Polymers carrying 2-oxazolidinone were also prepared through the homopolymerization and copolymerization of 4-(2-oxo-5-oxazolidinylmethoxy)phenyl acrylate. The effective concentration of 2-oxazolidinone residue in the polymers, which is accessible to phenol, was determined on the assumption that the polymer-bound 2-oxazolidinone and phenol formed a 1 : 1 complex. 2-Oxazolidinone and a mercury atom formed a 2 : 1 complex; this relation on the molar ratio applies to all forms of complexes between the mercury atom and the 2-oxazolidinone residue in the polymers.

Polymer complexes stabilized through hydrogen bonds: A semiquantitative theoretical model

AbstractMany studies have been devoted to the formation and behavior of polymer complexes. Unfortunately, the complexity of such systems do not allow a rigorous theoretical approach presently. In this paper we develop a semiquantitative theoretical model for cooperative association between macromolecules. The model is especially adapted for reversible polymer complexes stabilized through weak interactions, e.g., through hydrogen bonds. Theoretical predictions are compared with potentiometric and viscometric experimental results of poly(acrylic acid)/polybase system and a good agreement is established. The influence of parameters such as degree of neutralization of the polyacid, concentration, and molecular weight of polymers is also conveniently predicted.

Polymer complexes stabilized through hydrogen bonds. Influence of “structure defects” on complex formation: Potentiometric study

Polyacids form polymer complexes with polybases (proton acceptors) through hydrogen bonds. This result is well-known for homopolymer/homopolymer mixtures but only a few studies have been devoted to homopolymer/copolymer pairs because of the complexity of such systems. In this study a very simple model is proposed to take into account the influence of uncomplexable groups in the copolymer chain on complex formation. Several polybases (polyoxyethylene, polyvinylmethylether, polyvinylpyrrolidone) are used as homopolymers, and partially neutralized poly(acrylic acid) as copolymer; the acrylate groups are uncomplexable and behave as structure defects. It was found that the degree of complexation increases continuously with the concentration ratio [polybase]/[polyacid]. There is an exponential relation between the degree of complexation and the number of structural defects on the copolymer chain.

Kinetics of polymer-induced flocculation of cellulosic fibers in turbulent flow

The kinetics of polymer-induced flocculation in turbulent suspensions of cellulosic fibers were investigated. To measure the degree of flocculation a measuring principle based on frequency analysis of back-scattered laser light was used. The degree of flocculation, given as a flocculation index and an average diameter of the flocs formed, is defined from a wavelength power spectrum. Experiments show that the flocculation process is very rapid and that almost all the flocculation is completed in less than two seconds. Results obtained with polyethyleneoxide and a phenolic resin are discussed in terms of a network flocculation mechanism. Experiments with a dual polymer system, anionic polyacrylamide and a cationic polycondensate between a dimethylamine and epichlorohydrin, indicate that polymer complex formation is the most probable flocculation mechanism and that the cationic polymer has to be pre-adsorbed onto the cellulosic fibers to give maximum flocculation at a given addition level. The third flocculation system investigated, a highmolecular-mass cationic polyacrylamide ( M w $ ̃ 10 7), also shows rapid flocculation, suggesting very rapid polymer adsorption. Theoretical values for both the macroscale and the microscale of turbulence are calculated and it is suggested that turbulent eddies may affect both fiber flocculation and floc rupture. It is also suggested that turbulence may markedly increase the rate of polymer adsorption.

Kinetics of polymer-induced flocculation of cellulosic fibers in turbulent flow

The kinetics of polymer-induced flocculation in turbulent suspensions of cellulosic fibers were investigated. To measure the degree of flocculation a measuring principle based on frequency analysis of back-scattered laser light was used. The degree of flocculation, given as a flocculation index and an average diameter of the flocs formed, is defined from a wavelength power spectrum. Experiments show that the flocculation process is very rapid and that almost all the flocculation is completed in less than two seconds. Results obtained with polyethyleneoxide and a phenolic resin are discussed in terms of a network flocculation mechanism. Experiments with a dual polymer system, anionic polyacrylamide and a cationic polycondensate between a dimethylamine and epichlorohydrin, indicate that polymer complex formation is the most probable flocculation mechanism and that the cationic polymer has to be pre-adsorbed onto the cellulosic fibers to give maximum flocculation at a given addition level. The third flocculation system investigated, a high-molecular-mass cationic polyacrylamide ( M w∼10 7), also shows rapid flocculation, suggesting very rapid polymer adsorption. Theoretical values for both the macroscale and the microscale of turbulence are calculated and it is suggested that turbulent eddies may affect both fiber flocculation and flee rupture. It is also suggested that turbulence may markedly increase the rate of polymer adsorption.

Functional monomers and polymers. CXXXI.. Synthesis and interaction studies on polyacrylamide and polymethacrylamide derivatives containing nucleic acid bases

AbstractAcrylamide and methacrylamide derivatives of nucleic acid bases were prepared from the corresponding aminoethyl derivatives. Free‐radical polymerization of these monomers in water or in organic solvents gave their polymers. From the studies of the polymer complex formation by UV spectroscopy, it was found that extremely stable polymer complexes were formed between complementary polymers containing nucleic acid bases.

Functional monomers and polymers. CXXI. Methylation and interaction studies on adenine containing polymethacrylate derivatives

AbstractStudies of the methylation of polymethacrylate derivatives with adenine bases were made in comparison to those with uracil bases. The polymethacrylate derivatives with adenine bases were methylated by using methyl iodide in dimethyl sulfoxide solution to produce polymers that contained N1‐methyladenine and N1, N6‐dimethyladenine units. The products were identified by spectroscopic data and by preparing their model compounds. The methylated polymers obtained were further applied in a study of polymer complex formation with uracil‐base polymers.

Functional monomers and polymers. CX. Methylation and interaction studies on uracil‐containing polymethacrylate derivatives

AbstractA polymethacrylate derivative containing uracil bases was methylated by using methyl iodide or dimethyl sulfate to give polymers containing 3‐methyluracil derivatives. In the case of methylation with dimethyl sulfate, sulfonation at 5‐position of the bases occurred in addition to the methylation at N‐3 position. The methylated polymers thus obtained were used further for the study of polymer complex formation with polymethacrylate containing adenine base.

Poly- N-vinylamides, complexation and conformational changes in aqueous solution

Interaction between small molecules (iodine and 1-anilinonaphthalene-8-sulphonate) and poly- N-methylacetamide (PVMA), poly- N-vinylcaprolactam (PVCL), poly- N-vinylpyrrolidone (PVP) and copolymers of N-vinyleaprolactam with N-vinylpyrrolidone (CP VCL-VP) and with N-vinyl- N-methylacetamide (VMA) were studied. All the polymers formed complexes with the small molecules. The stability constant for the complexes with the probe increases in the series PVMA < PVP < copolymer < PVCL indicating the essential role of hydrophobic interactions in the complex formation. With increasing temperature of aqueous solution from 18 to 33°, the constant decreased for PVP, PVMA and copolymers with low VCL content and increased for PVCL. A folding of PVC coils was observed over the temperature range, demonstrating a relationship between the conformational changes of macromolecules and the polymer complex formation. Addition of PVCL, PVMA and PVP to aqueous I 3 − solution brings about a shift of λ max from 350 nm for free triiodide ions to 372, 367 and 364 nm respectively. It is explained by different dipole moments of the side substituents. The stability constant for the polymers and I 3 − was estimated as approx. 10 5 M. The ability of the polymers to form complexes depends on chainlength. The greatest loss of the ability was observed for PVCL with M n changing from 6 × 10 3 to 2 × 10 3. Interaction of the polymers with I 3 − is accompanied by a conformational shrinking of coils. In the case of the probe, forces of electrostatic repulsion between negative charges of sulphonate groups result in an unfolding of polimer coils.

Binding of methyl orange and its homologs by polyion complex in ethylene glycol

AbstractThe extent of binding of methyl orange, ethyl orange, propyl orange, and butyl orange by a polyion complex, which consists of equimolar sodium polymethacrylate and a piperidinium cationic polymer, was measured in ethylene glycol at 25, 30, and 35°C. The effects of aqueous and nonaqueous media on the binding of the dye by the polymer matrix were compared. In ethylene glycol only noncooperative binding (Langmuir type) was observed, whereas two modes of binding, noncooperative and cooperative, were involved in the aqueous environment. The first binding constants and the thermodynamic parameters associated with the binding in ethylene glycol were evaluated. The polymer matrix exhibited a higher affinity toward the dye in ethylene glycol than in water at low concentrations of free dye and bound these anionic cosolutes with different hydrophobicities but the same affinity as in ethylene glycol. These interactions are highly exothermic and characterized by relatively large negative entropy changes. Electrostatic forces are the principal contributors to the dye–polymer complex formation. The binding behavior observed in the nonaqueous solvent is reasonably accounted for in terms of disappearance of hydrophobic interactions between the dye and the polymer and an increase in electrostatic attraction between the anionic small molecule and the positively charged sites on the polyion complex.

Complex formation of amphiphilic polymers with azo dyes and their photoviscosity behavior

AbstractThe hydrophobic interaction of amphiphilic copolymers, which contain 2‐hydroxyethyl methacrylate(HEMA) and 1vinyl‐2‐pyrrolidone (VPy), with Methyl Orange (MO) was compared with that of HEMA‐acrylamide (AAm) copolymers to deduce the correlation between their complexation ability in a photochromic azo dye and the photoviscosity effect in aqueous copolymer/dye complex solution. On the basis of the dialysis data and fluorometric analysis it appeared that the complexation dependence on HEMA content in the copolymers was due to the hydrophobic interaction between the polymer and the dye. For a comparable HEMA content AAm copolymers bound less MO than VPy copolymers. It was confiied by photoviscosity measurements that the conformation of the complex composed of photochromic azo dye and HEMA copolymer changed reversibly in response to the photo‐ and thermal isomerization of the dye. In HEMA‐AAm copolymer systems the photoviscosity effect was small compared with that of HEMA‐VPy copolymer systems. From these results it was concluded that the complexation ability of polymers due to the hydrophobic interaction was an important factor in producing a large photoinduced conformational change in water.

Aggregation of poly(methacrylic acid)‐poly(ethylene oxide) complex in aqueous medium

AbstractIt is known that poly(methacrylic acid) and poly(ethylene oxide) interact with each other through hydrogen bonds and form polymer complexes in an aqueous medium. The initially formed polymer complexes were considered to exist in a semi‐stable state, and they aggregated through desolvation and hydrophobic interaction. A successive aggregation of polymer complexes was observed following the rapid initial complexation. The aggregation was affected by some chemical factors e.g., polymer concentration, temperature, pH and so on. These effects were measured as the changes of the molecular shape by means of laser‐light scattering, turbidity measurements, and scanning electron microscopy. It was observed that lower pH and higher temperature made the aggregation faster within such experimental conditions as pH 2–7, 20–50°C. The aggregates were nearly spherical with almost the same diameter (200 nm), and spontaneously grew larger with time.

Macro-inorganics. Part 6. Protonation and complex formation of a new series of polymers whose repeating units behave independently

The protonation and copper(II) complex formation of some new polymers with a poly(amido-amine) structure has been studied in aqueous solution by potentiometric, calorimetric, and spectroscopic techniques. The polymers are characterized by the fact that no ring structures are present along the main chain between tertiary amino-groups of different units. The results indicate the monomeric units of this new family of poly(amido-amines) behave independently towards both protonation and complex formation. Comparison with previously studied poly(amido-amines) shows that the presence of linear diamide moieties in place of 1,4-diacylpiperazine rings [as in the previously studied poly(amido-amines)] has a slight influence on the protonation constants, although differences may be observed in the thermodynamic functions ΔH⊖ and ΔS⊖. Significant differences are observed in copper(II) complex formation.

Fluorescence study of the formation of polymer complexes through hydrogen bond

Fluorescence study of the formation of polymer complexes through hydrogen bond

Solvent effect on the complex formation of poly(methacrylic acid) with proton‐accepting polymers

AbstractA pair of polymers may interact with each other through hydrogen bond and form a polymer complex. Such polymer complex formation is affected by several chemical and physical factors, especially by solvent properties. This solvent effect was studied in the complex formation of poly(methacrylic acid) with a series of proton‐accepting polymers in aprotic solvents. The extraordinary behaviour of polymer complexes in dimethyl sulfoxide was well explained in terms of the strong interaction between proton‐donating polymer and dimethyl sulfoxide. In addition, a stronger proton‐accepting polymer, viz. poly(N,N‐dimethyl‐N′,N′,N″,N″‐tetramethylenephosphoramide), was synthesized. This polymer could form a polymer complex with poly(methacrylic acid) through hydrogen bond even in dimethyl sulfoxide. Selective polymer complex formation was achieved by controlling such solvent properties.

Functional monomers and polymers. LXXI. Conformation and interaction studies of poly‐L‐lysine derivatives with pendant nucleic acid bases

AbstractCopolymers of L‐lysine and L‐lysine derivatives which contained nucleic acid bases substituted on the Nε position were synthesized by grafting nucleic acid derivatives onto poly‐L‐lysine. The conformation and interaction of these copolymers in solution were studied by using spectroscopic measurements. They existed in helical conformation at neutral pH values, and the polymer complex formation among them was examined by ultraviolet (UV) measurements in organic solvents. A decrease in the nucleic acid base content of the copolymers resulted in a decrease in helical structures and also in interactions with the polymer‐containing complementary bases.

A conductance stopped-flow study of polyelectrolyte systems. Dynamic conformational change of synthetic macroions and their complexation with neutral polymers

Two dynamic phenomena of polyelectrolyte systems, namely the rapid conformational changes of weak polyelectiolytes (polyacrylic acid (HPAA) and polyethylenimine, induced by pH-jump) and the complexation of HPAA with polyvinylpyrrolidone are first investigated by means of the conductance stopped-flow (kappa-SF) technique. The pH-induced relaxations observed by mixing an aqueous solution of HPAA or polyethylenimine with water containing a tiny amount of alkali or acid, are safely ascribed to the conformational transition of the macroions between the compact "coil" and the stretched "rod" forms. The relaxation times are large at high degrees of neutralization and for "rod" conformation. Tentative values for the thermodynamic parameters of the dynamic conformational changes are obtained and discussed. The reaction rates of the polymer complex formation and dissociation of HPAA with polyvinylpyrrolidone are also determined using the kappa-SF method. The association constant and the rates of formation and dissociation are 1.84 x 10(3) M(-1), 9.4 x 10(4) M(-1) s(-1) and 51 s(-1) at 10 degrees C, respectively. We then derive the thermodynamic parameters from the above results.