Viscometric Interaction Parameters Research Articles

Intermolecular interactions and self-assembling of polyurethane with poly(vinyl alcohol) in aqueous solutions

The paper discusses the viscometric behaviour of aqueous solutions of polyurethane (PU), poly(vinyl alcohol) (PVA), and their mixtures of different compositions at 37 °C. Two models were used to determine the intrinsic viscosity and viscometric interaction parameters: the classical Huggins equation and the new Wolf approach. The higher hydrodynamic volume of PVA/PU mixtures as compared with the individual macromolecules can be explained by the new thermodynamic approache. The viscometric data were used to evaluate different miscibility parameters which are discussed as a function of PVA/PU mixture composition. The different types of interactions occurring in solution contribute to the miscibility of the two polymers and the preferential PVA-PU intermolecular interactions are responsible for the self-assembling phenomena. The thermodynamic conditions are favorable for the formation of the mixed coils containing PVA macromolecules and PU micelles.

A versatile viscometric method for the study of dissolved proteins, exemplified for casein micelles in ammoniacal solutions

Viscosities of casein solutions were measured within the dilute range in ammoniacal water and in saline solvents containing different amounts and different kinds of salt. All these data are modeled quantitatively by means of an approach accounting for the polyelectrolyte character of casein micelles. Two parameters are required: The intrinsic viscosity [η ] and a viscometric interaction parameter β. The behavior of casein is compared with that of chain-like polyelectrolytes. For both polymers one observes a pronounced reduction of [η ] with increasing salt concentration. However, for casein the decline of [η ] is less pronounced by more than an order of magnitude and depends on the chemical nature of the salt. In the case of low solvent salinities, the β values are in both cases positive (less than exponential increase of the viscosity with rising solute concentration). However, for casein β changes from positive to negative (more than exponential increase) with rising salt concentration. Reasons for the dissimilarities between the two types of polyelectrolytes are discussed.

Consequences of linking charged and uncharged monomers to binary copolymers studied in dilute solution. Part I: Viscometric behavior of the homopolymers, the effects of charging, and uncommon salt effects

Intrinsic viscosities, generalized intrinsic viscosities and viscometric interaction parameters were measured for aqueous solutions of poly(ethylene oxide) [PEO], poly(N,N-dimethyl aminoethyl methacrylate) [PR] (uncharged) and for poly{[2-(methacryloyloxy)ethyl] trimethylammonium iodide} [PR+] (charged) within a wide range of molar masses. In this manner it was possible to establish the information required for the study of non-additivity effects upon the formation of binary copolymers from the monomers specified above. The following additional items were of particular interest: The effects of charging PR to PR+ and the composition dependence of the coil overlap in the case of saline (NaCl, CaCl2 and NaI) solvents. NaCl turned out to be much less efficient in shielding the electrostatic interactions than the other salts due to its large tendency to form ion pairs in solution.

Insight into miscibility behaviour of cellulose ester blends with N-vinyl pyrrolidone copolymers in terms of viscometric interaction parameters

We previously offered miscibility maps for blend systems of cellulose esters (CEs) including cellulose acetate (CA), propionate (CP), and butyrate (CB) with vinyl copolymers containing an N-vinyl pyrrolidone (VP) unit, i.e., poly(N-vinyl pyrrolidone-co-vinyl acetate) [P(VP-co-VAc)] and poly(N-vinyl pyrrolidone-co-methyl methacrylate) [P(VP-co-MMA)]; the maps were constructed based on data of thermal analysis as a function of the degree of ester substitution (DS) of the CE component and the VP fraction in the copolymer component. The blend system using CP among the three CEs imparted the largest region of miscible pairings with the vinyl copolymers, and both of the maps for the CP/P(VP-co-VAc) and CP/P(VP-co-MMA) systems comprised a “miscibility window” associated with the respective copolymer compositions at high DSs of >2.65. The present work was made to interpret the expansion of the miscible markings for the CP/copolymer systems in comparison with the cases using CA and CB, in terms of a Krigbaum–Wall interaction parameter (μ) obtained by solution viscometry for selective polymer pairs involved in the respective CE/copolymer blends. The results of μ measurements were in good accordance with the earlier miscibility estimations. The assessment of very small negative μ values (i.e., extremely weak repulsion) for CP/PVAc and CP/PMMA combinations and that of considerably larger negative μ values for PVP/PVAc and PVP/PMMA combinations enabled us to give a rational explanation for the CP systems. The strongly repellent character of the two different monomer units constituting the copolymers permits accession of the CP component (DS > 2.65) to them, which would be responsible for the advent of the miscibility window. Further expansion of the window observed when cellulose acetate propionate (CAP) was adopted instead of CP as the CE component was also well explained on the basis of a μ data indicative of additional intramolecular repulsion in the CAP side.

Intrinsic Viscosities of Polyelectrolytes: Determination and Modeling of the Effects of Extra Salt

Based on early measurements of J. J. Hermans and co-workers (D. T. F. Pals, J. J. Hermans, Recl. Trav. Chim. Pays-Bas 1952, 71, 513-520; D. T. F. Pals, J. J. Hermans, J. Polym. Sci. 1950, 5, 733-734; D. T. F. Pals, J. J. Hermans, J. Polym. Sci. 1948, 3, 897-898), the present contribution demonstrates how primary data should be evaluated in order to obtain reliable intrinsic viscosities. This procedure yields detailed information on the changes of the intrinsic viscosities and of the corresponding viscometric interaction parameters caused by an increasing salinity of water. Both quantities decline from a maximum value in the pure solvent to a minimum value, which is approached in the limit of sufficiently high salt concentrations, and can be modeled quantitatively by means of a Boltzmann sigmoid. Particular attention is paid to the significance of results obtained by means of the method of isoionic dilution, proposed by J. J. Hermans and co-workers.

Intrinsic viscosities of polyelectrolytes in the absence and in the presence of extra salt: Consequences of the stepwise conversion of dextran into a polycation.

Viscosities of dilute polymer solutions were measured in capillary viscometers for samples varying in their fraction f of charged units from 0.00 to 0.90. The dependence of the logarithm of the relative viscosity on polymer concentration c is in all cases reproduced quantitatively by three characteristic parameters: [η], the intrinsic viscosity; B, a viscometric interaction parameter (related to the Huggins constant); [η], a parameter required only for polyelectrolytes at low concentrations of extra salt. In pure water [η] increases more than 80 times as the fraction f rises from zero to 0.90 and [η] starts from zero and goes up to ≈71mL/g. Upon the addition of NaCl [η] decreases by at least one order of magnitude (depending on the value of f). The observed dependences of log [η] on logcsalt can be modeled quantitatively by Boltzmann sigmoids.

Molecular interaction in some polymeric additive solutions containing styrene-hydrogenated butadiene copolymer

The miscibility of styrene-hydrogenated butadiene copolymer (SHB) with different constituents of polymer additives for lubricating mineral oils was studied in dilute solution regime, using xylene as model solvent, at 30 °C, in a wide range of polymer blend compositions. The systems studied were SHB/poly(ethylene- co-propylene) (EPC), SHB/poly(methyl methacrylate) (PMMA), SHB/poly(dodecyl methacrylate) (PDDMA) and SHB/polystyrene (PS). The viscometric interaction parameters were calculated according to the Krigbaum–Wall and Catsiff–Hewett models of ideal viscometric behavior. Strong repulsive interactions were found in SHB/PMMA and SHB/PDDMA systems pointing to immiscibility. SHB/EPC and SHB/PS deviated much less from ideality. The results were compared to the theoretical estimation of interaction in polymer blends in the absence of solvent, using the Coleman–Graf–Painter approach. No correlation was observed between the interaction in the bulk and in solution.

Miscibility on blends of PVA and PFSA by viscometry

The intrinsic viscosity and viscometric interaction parameters of perfluorosulfonic acid (PFSA) and poly(vinyl alcohol) (PVA) were measured by dilute solution viscometry. The miscibility between PFSA and PVA was estimated by the criteria of ΔB and µ. The results indicated that PFSA and PVA were completely miscible for any weight fraction in aqueous solution.

Investigation on polyacrylonitrile/cellulose acetate blends

The molecular interactions of polyacrylonitrile (PAN) and cellulose acetate (CA) were investigated thoroughly via dilute solution viscometry in dimethylformamide (DMF) as a common solvent at 30°C. The intrinsic viscosities and viscometric interaction parameters were experimentally determined for both binary (polymer/ dimethylformamide) and ternary (PAN/CA/dimethylformamide) systems. As all investigated PAN/CA ternaries evidenced negative viscometric interaction parameter values (δb & δk <0), the existence of repulsive intermolecular interactions was deduced, and PAN/CA blends were assigned as immiscible. Moreover, the results of microscopy photograph analysis indicated that pure PAN film evidences a homophasic structure, and the size of the phase domain increases gradually with increases in CA. In DSC analysis, it was determined that the glass transition temperature of the blend film increased slightly with increases in the CA content of the blend film.

Miscibility and interactions of polystyrene/polyolefine and polystyrene/poly( n-alkyl methacrylate) mixtures in dilute xylene solutions

The miscibility and intermolecular interactions between polystyrene (PS) and poly(ethylene-co-propylene) (EPC), as well as between PS and long-chain poly(alkyl methacrylates) (PAMA), namely, poly(dodecyl methacrylate) (PDDMA) and poly(octadecyl methacrylate) (PODMA), in dilute xylene solutions at 30 °C were studied. Investigated polymers are widely used as rheology modifiers, i.e. viscosity index improvers and pour point depressants for lubricating mineral oils. The specific and reduced viscosities of two- and three-component polymer solutions as well as intrinsic viscosities and Huggins’ parameter values were determined as functions of the polymer mixture composition and overall polymer concentration. The reduced viscosity was found to be linearly dependent on the overall polymer concentration. The observed viscosities of polymer mixtures were intermediate to those of the mixture constituents; the values decrease in the order: EPC > PS > PAMA. The specific viscosities of all the polymer mixtures obtained as the experimental results and calculated applying the Catsiff–Hewett and Krigbaum–Wall theoretical equations were considered. Since all the polymer/polymer pairs showed the negative viscometric interaction parameter values (Δ b 12 < 0), the PS/EPC and EPC/PAMA mixtures were found to be immiscible. The observed repulsive molecular interactions originate from the differences in polymer composition and molar masses. This conclusion was supported by calculations employing the group contribution approach of Coleman, Graf and Painter. The calculated values of interaction parameters for (co)polymer blends, Λ 12, were 5.47, 6.42 and 13.1 J cm −3 for PS/PDDMA, PS/PODMA and PS/EPC, respectively.

Miscibility studies on poly(ethylene glycol)/dextran blends in aqueous solutions by dilute solution viscometry

AbstractMiscibility of poly(ethylene glycol) (PEG) with dextran (Dx) was investigated by dilute solution viscometry. Dilute solution viscosity measurements were made on ternary systems, polymer (1)/polymer (2)/solvent (H2O), for four different average molecular weights of PEG and Dx. The intrinsic viscosity and viscometric interaction parameters were experimentally measured for the binary (solvent/polymer) as well as for the ternary systems by classical Huggins equation. Degree of miscibility of these polymer systems was estimated on the basis of the four following criteria: (1) the sign of the ΔkAB, (2) the sign of α, (3) the sign of ΔB, and (4) the sign of the μ. Based on the sign convention involved in these criteria, immiscibility was observed in most systems. The miscibility of all these systems in accordance with the interactions between the unlike polymer chains rather the polymer–solvent interactions were investigated depending on molecular weight of polymer sample. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 453–460, 2004

Viscometric study of miscibility and interactions of some polyolefines and poly(alkyl methacrylates) in dilute xylene solutions

Miscibility and molecular interactions of poly(ethylene-co-propylene), EPC, and a series of homologous poly(alkyl methacrylates), PAMA, [namely: poly(methyl methacrylate) (PMMA), poly(dodecyl methacrylate) (PDDMA) and poly(octadecyl methacrylate) (PODMA)] were thoroughly investigated by dilute solution viscometry in xylene as a common solvent at 30 °C. Intrinsic viscosities and viscometric interaction parameters were experimentally determined for binary (polymer/xylene) and ternary (EPC/PAMA/xylene) systems. Since all investigated EPC/PAMA binaries exhibited negative viscometric interaction parameter values (Δ b 12<0), the existence of repulsive intermolecular interaction was deduced and EPC/PAMA blends were assigned to be immiscible. The conclusion was supported by calculations employing the group contribution approach of Coleman, Graf and Painter. The calculated values of interaction parameters for (co)polymer blends, Λ 12, were 7.60 J cm −3, 1.63 J cm −3 and 1.15 J cm −3 for EPC/PMMA, EPC/PDDMA and EPC/PODMA, respectively. According to the viscometric and blend interaction parameter values, the immiscibility of polymeric components decreases in the following order: EPC/PMMA≫EPC/PDDMA>EPC/PODMA. The values of Huggins’ constants in xylene solutions were found to be relatively high, i.e. 1.8, 1.2 and 2.0 for PMMA, PDDMA and PODMA, respectively, pointing to a certain degree of self-association between polymer molecules. However, for EPC/PAMA/xylene systems those values decreased sharply with the increase of EPC content in the ternaries. The superposition of the two effects: (1). repulsive interaction between EPC and PAMA molecules; and (2). self-association of PAMA molecules (affected by the dilution upon introduction of EPC) was proposed to influence the viscosity of investigated systems as a function of polymer mixture composition. The approach of Bohdanecký and Kovář was used for the estimation of self-association constants of PAMAs in xylene. The same approach was extended to ternary systems; in that form it was able to account for the compositional variation of viscometric interaction parameters.

Viscometric study on the compatibility of some water-soluble polymer–polymer mixtures

Dilute solution viscosity behavior of three water-soluble polymer mixtures has been studied at 20 °C. The ternary systems assayed are distilled water/sodium carboxymethylcellulose (CMC)/polyacrylamide (PAM), distilled water/methylcellulose (MC)/CMC, and distilled water/polyvinylpyrrolidone (PVP)/MC. The intrinsic viscosity and the viscometric interaction parameters have been determined for the binary (distilled water/polymer) and ternary (distilled water/polymer1/polymer2) systems. Degree of compatibility of these polymer systems was estimated on the basis of five criteria: (i) the sign of Δ b m, (ii) the sign of Δ b m ′, (iii) the sign of Δ[ η] m, (iv) sign of thermodynamic parameter α, and (v) the sign of modified thermodynamic parameter β. Based on the sign convention involved in these criteria, compatibility/miscibility was observed in CMC/PAM and MC/CMC systems and incompatibility/immiscibility in PVP/MC system. The FTIR analyses also support the obtained results. The miscibility/compatibility of all these systems is in accordance with the interactions between the unlike polymer chains rather than the polymer–solvent interactions.

Viscosity of polymer/solvent systems: Quantitative description on the basis of molecular surfaces

A model for the description of the viscosity of polymer/solvent systems made up of homologues, developed earlier, is generalized to normal polymer solvent mixtures. It is based on three premises: (i) the dissipation of energy takes place at the molecular interfaces; (ii) the friction between solvent and solute varies with composition due to a change in the flow mechanism (drainage of coils); and (iii) the specific coil volume generally also depends on polymer concentration. The resulting simple expression contains four system-specific parameters: a geometric factor γ, which accounts for the differences of the surface to volume ratios of the components; a viscometric interaction parameter α, which measures the friction between solute and solvent in the case of fully draining polymer coils; [η], the specific hydrodynamic volume of the polymer at infinite dilution (intrinsic viscosity), and [η]Θ the specific hydrodynamic volume under Θ conditions. The suitability of this model is demonstrated by means of ext...

Viscometric study on the compatibility of polymer–polymer mixtures in solution

Abstract The viscosity behaviour of mixtures formed by two uncharged polymers in dilute solution has been studied at 25°C. The ternary systems assayed, and denoted solvent (1)/ polymer (2)/ polymer (3), have in common the poly(ether sulphone) (PES) as polymer 2, and poly(vinylidene fluoride) (PVDF), poly(methyl methacrylate) (PMMA) or poly(styrene) (PS) as polymer 3. The intrinsic viscosity and the viscometric interaction parameters have been experimentally measured for the binary (solvent/polymer) as well as for the ternary systems, and also theoretically evaluated for the latter. The estimation of the compatibility degree of the above polymer pairs have been done by means of three criteria: (i) the sign of Δbm, according to the traditional formalism developed by Krigbaum and Wall; (ii) the sign of a new defined Δb′m; and (iii) the sign of Δ[η]m. The two last criteria are proposed in this work and are based on treating the viscosity interaction parameter and the intrinsic viscosity as excess properties by similarity with those of real solutions. Both methods provide compatibility predictions in agreement with those made with the traditional one but they are much more simple in handling the calculations. Finally, the observed compatibility behaviour follows the order: (PES+PMMA)≫(PES+PVDF)>(PES+PS), in dimethylformamide as solvent, at least in the assayed composition range.

Evaluation of K ⊖ from [η]-M -data of binary and ternary polymer systems

Unperturbed dimensions of flexible linear macromolecules can be obtained from [η]-M-data in any solvent, good or poor, single or mixed. Usually Kθ is estimated by a relationship between [η]/MW0.5 and Mw0.5 first proposed by Burchard and by Stockmayer and Fixman. But, it is well-known that the Burchard-Stockmayer-Fixman-plot shows downward curvature, especially for good solvent systems. Various efforts have been made to achieve relations with better linearity. One of the first was the semi-empirical relation between ([η]/Mw0.5)0.5 and Mw/[η] by Berry. Predicting a relationship of the excluded volume parameter z to the viscosity expansion factor by α5η instead of α5η Tanaka obtains that ([η]/Mw0.5)5/3 is linear in Mw0.5. By allowing for the dependence of the viscometric interaction parameter B, which is correlated to the second virial coefficient A2, on molar mass, Gavara, Campos and Figueruelo predict a linear dependence of [η]/Mw0.5 against A2.Mw0.5. It is not our intention here to discuss the validity of these theories, but to compare them with experimental data.

Evaluation of unperturbed dimensions parameter from intrinsic viscosity data of any binary or ternary polymer system

AbstractTaking into account the dependency on molar mass of the viscometric interaction parameter B, the modified Stockmayer‐Fixman‐Burchard equation ([η]/M1/2) = KΘ + C″ · A2 · M1/2 is obtained. It relates the intrinsic viscosity, [η], to the second virial coefficient, A2, and to the unperturbed dimensions parameter, KΘ, with C″ being a constant. Hereupon, KΘ can be determined from [η] and A2 data of any binary (solvent/polymer) and/or ternary (solvent 1/solvent 2/polymer) system, BPS and/or TPS. Because of the scarcity of reliable sets of [η] and A2 values mostly for TPS, the application of the above equation to obtain KΘ coefficients rests limited. This limitation can be surmounted by an A2 evaluation from [η] data and trial KΘ values through two‐parameter theories taking into account the interpenetrating factor between chains, ψ, as evaluated from the Flory‐Krigbaum‐Orofino (FKO) theory, from a modified FKO theory, or from the Kurata‐Yamakawa theory. An interative process is followed until coincidence between assumed and evaluated KΘ values is reached. The method has been applied to the KΘ evaluation from [η] with literature data for diverse BPS and TPS of polystyrene, poly(methyl methacrylate), poly(dimethylsiloxane), poly(2‐vinylpyridine) and poly(1‐vinyl‐2‐pyrrolidone), with the respective KΘ values 7,5 · 10−2, 5,8 · 10−2, 8,2 · 10−2 and 6,4 · 10−2, 7.2·10−2 and · 6,4 · 10−2 mL · mol1/2 · g−3/2 being obtained. Moreover, a single C″ value, mainly C″ = 0,52, holds for all five polymers.

Relationships between transport and equilibrium properties in ternary systems of unbranched alcohol/3‐heptanone/poly(1‐vinyl‐2‐pyrrolidone)

AbstractIntrinsic viscosities, [η], second virial coefficients, A2, and interaction potentials, g12, for the ternary systems alcohol (1)/3‐heptanone (2)/poly(1‐vinyl‐2‐pyrrolidone) (3), with the unbranched alcohols methanol, ethanol and 1‐propanol, were determined at 25°C. Taking into account the dependence of the viscometric interaction parameter, B, with the molecular weight of the polymer, the unperturbed dimensions parameter, KΘ, of the polymer was unambiguously obtained. Relationships between ΔKΘ (defined as ΔKΘ = ΔK − KΘ) and excess Gibbs energies, GE, and between excess viscosity, Δ[η], and GE allow to obtain equations relating A2 to ΔKΘ or to Δ[η]. Therefore, A2 can be evaluated from experimental data of [η].

Solution properties of polyelectrolytes—V. Viscometric study of mixed polyanions in pure water

A viscometric study of sodium polystyrene sulphonate (NaPSS) and sodium poly( l-glutamate) (NaPLG) in salt-free water has been carried out as a function of the total concentration, c m, and the concentration of one polyelectrolyte at fixed concentration of the other. The influences of the molecular weight and concentration are considered in order to establish the degree of compatibility. For the first time, an equation is proposed to define the reduced viscosity of the NaPSS + NaPLG mixture in water. The viscometric interaction parameter, B m, taking into account the electrostatic and thermodynamic interactions between both polyions, is defined as a geometrical mean of the contribution of each one. Finally, the compatibility of NaPSS + NaPLG mixtures as a function of individual polyion concentration and molecular weight is analysed in the light of B m.

Viscometric study of dilute solutions of polymer-polymer mixtures. Temperature and composition effects

Viscometric interaction parameters between pairs of homopolymers or an acidic and a basic copolymer in dioxane were determined by two procedures: (a) determination of the intrinsic viscosity of polymer (A) in dilute dioxane solutions of polymer (B) at 30°; (b) determination of the Huggins constants for 1:1 mixtures of polymers at 50°. The Δb 23 values obtained by these methods were different but positive and they increased from the most incompatible to the completely compatible system. Non-linear relations were found for the Huggins constant vs temperature and the intrinsic viscosity vs composition.