Huggins Constant Research Articles

Sуnthesis of terpene–methacrylic acid copolymers and their effect on the stability of inorganic dispersions in the presence of cationic surfactants

Copolymers of methacrylic acid and natural terpene monomers (α-pinene; β-pinene; ∆3-karene) with the molecular weight of (0.3–0.5)∙104 and a content of carboxyl groups of 14.5–16.3 % were synthesized. For the synthesized copolymers, hydrodynamic radius and the Kuhn segment, which characterizes flexibility of a polymer chain, were determined, as well as the Huggins constant in aqueous and saline solutions, and concentration regions for formation of supramolecular structures. In the presence of a cationic surfactant (benzetonium chloride, Hyamine), depending on the concentration of copolymers in the system, polymer-surfactant complexes were formed in soluble and insoluble forms. It has been shown that the effectiveness of the stabilizing action of soluble complexes with respect to an aqueous dispersion of calcium carbonate increases with an increase in the content of nonpolar groups in the polymer chain. A cationic surfactant (Hyamine) has been proposed as a precipitant in the method for the quantitative determination of carboxyl-containing polymers in aqueous and saline media.

Therapeutic phosphorodiamidate morpholino oligonucleotides: Physical properties, solution structures, and folding thermodynamics

Elucidating the structure-function relationships for therapeutic RNA mimicking phosphorodiamidate morpholino oligonucleotides (PMOs) is challenging due to the lack of information about their structures. While PMOs have been approved by the US Food and Drug Administration for treatment of Duchenne muscular dystrophy, no structural information on these unique, charge-neutral, and stable molecules is available. We performed circular dichroism and solution viscosity measurements combined with molecular dynamics simulations and machine learning to resolve solution structures of 22-mer, 25-mer, and 30-mer length PMOs. The PMO conformational dynamics are defined by the competition between non-polar nucleobases and uncharged phosphorodiamidate groups for shielding from solvent exposure. PMO molecules form non-canonical, partially helical, stable folded structures with a small 1.4- to 1.7-nm radius of gyration, low count of three to six base pairs and six to nine base stacks, characterized by -34 to -51kcal/mol free energy, -57 to -103kcal/mol enthalpy, and -23 to -53kcal/mol entropy for folding. The 4.5- to 6.2-cm3/g intrinsic viscosity and Huggins constant of 4.5-9.9 are indicative of extended and aggregating systems. The results obtained highlight the importance of the conformational ensemble view of PMO solution structures, thermodynamic stability of their non-canonical structures, and concentration-dependent viscosity properties. These principles form a paradigm to understand the structure-properties-function relationship for therapeutic PMOs to advance the design of new RNA-mimic-based drugs.

Rheology and molecular interactions in polyacrylonitrile solutions: Role of a solvent

We examined the rheological properties of polyacrylonitrile (PAN) solutions in seven solvents over a wide range of shear rates. These solutions were characterized using the Hansen solubility parameter. The viscosity of these dilute solutions was primarily determined by this parameter. However, above the crossover point (at c[η] > 0.7) not only viscosity but also nature of the solvents was found to be an important factor. At high polymer concentrations, certain solutions showed gelation tendency.This study aims to determine a correlation between the rheological properties of the solutions and the affinity of the solvent with PAN. These correlations are present for an intrinsic viscosity (or the Huggins constant), a second virial coefficient, and solubility parameter. However, in certain cases, experimental points do not correspond to general dependence. This is also observed for these solutions when presenting the data of viscoelastic measurements in G′–G″ coordinates: certain points deviate from the general dependence.A detailed infrared spectroscopy analysis has been used for examining these experimental results. It has been shown the water presence in the solvents and polymer solutions even than anhydrous solvents were used. Water presence tend to a solvent–water associate formation in the solutions. The solubility of PAN in these solvents and the gelation tendency depends on the polymer concentration, in addition to the structure and stability of the polymer–water associates. The experimental results obtained and the reported correlation made it possible to develop a subsequence of solvents used as per their affinity with PAN. The charactristics of dilute solutions were compared with the rheological properties of moderately concentrated solution.

Some Mechanical Properties Of Polyvinylalcohol / Zinc Oxide Nanoparticles As Thin Films And Solutions

The polymer was dissolved in twice distilled water, then nanoparticles were added to it. The flow time of the solutions was measured, then the viscosity was calculated and the surface tension of the solutions was measured by measuring the weight of the liquid drop. Solutions were left at room temperature to form thin films that were subjected to variable tension until they were cut and depending on the stress and strain of the samples. From the results, an increase in the stress borne by the samples was noted with an increase in the concentration of zinc oxide nanoparticles, and express the departure from the ideal elastic behavior has values ranging from 3.71 to 54, but quantity pertaining to the ideal elastic behavior has values ranging from 1.2 to 1.0. Increase viscosity of the solutions and their surface tension. This makes it clear that it is possible to change some properties of the PVA by adding zinc oxide nanoparticles, the sum of Huggins and Kraemer constants values indicates that the samples were dissolved in a good solvent, as they can be used in many areas of life such as industrial, medical applications.

Study of the formation of structures in solutions of chitosan – polyvinyl alcohol polymer blends

The aim of this work was the investigation of the formation of structures in solutions of individual polymers, as well as their blends with each other in buffer solvents with different values of pH. In this study we used a sample of chitosan (degree of deacetylation ~ 84 %, M = 130,000), which is a polycation when dissolved, and polyvinyl alcohol (r = 1.25 g/cm3, M = 5000). Buffer systems based on acetic acid and sodium acetate with pH = 3.8, 4.25, and 4.75 were used as solvents. Viscosimetry was used to determine the intrinsic viscosity, the degree of structuring, and the Huggins constant. The Kriegbaum method was used to determine the nature of the aggregates formed by the blend of the studied polymers. In the course of the research, it was shown that an increase in the pH of the acetate buffer used as a solvent was accompanied by a compression of the macromolecular coil (a decrease in intrinsic viscosity values), a deterioration in the quality of thesolvent (an increase in Huggins constant values), and an increase in the degree of polymer aggregation in a solution for chitosan polyelectrolyte. At the same time for a solution of polyvinyl alcohol the pH of the buffer practically did not affect the nature of the polymer-solvent interaction. It has been proved that polymer blends are characterized by an increase in aggregation processes and a decrease in the thermodynamic quality of the solvent in comparison with solutions of individual polymers. The size of the “combined” macromolecular coil, characterized by the intrinsic viscosity value for the polymer blend, which can be both above (buffer solvent with pH = 3.80) and below (buffer solvent with pH = 4.25 and 4.75) additivevalues, changed depending on the type of formed polymer-polymer aggregates (homo- or hetero-). It was established that the type of aggregates (homo- or hetero-) formed in solutions of polymer blends was determined not only by the thermodynamic quality of the used solvents, but also by the concentration of the polymers in the initial solutions

Determining the Conformation and Dimensions of the PEG Macromolecule in Water–PEG–NaOH Systems via Vicosometry

The kinematic viscosity of water–polyethylene glycol (PEG)–NaOH systems is investigated at a temperature of 293.15 K, 0–0.05 mol % of NaOH, and concentrations of PEG in the range of 0–5 g/dL. Fractions of polyethylene glycol with different molecular masses are considered (1000, 1500, 3000, 4000, and 6000). Based on experimental data for the kinematic viscosity at this concentration of NaOH, calculations are performed for the characteristic viscosity of the given solutions, the Huggins constant, parameter α in the Kuhn–Mark–Houwink equation, the swelling coefficient of macromolecules of polyethylene glycol, the characteristic viscosity in a θ-solvent, the mean-square distance of a macromolecular chain of PEG in solution and a θ-solvent, and the length of a Kuhn segment in solution and in a θ-solvent. It is found that the macromolecular coil of polyethylene glycol is permeable to the surrounding liquid (water–NaOH). Upon an increase in the concentration of NaOH, the volume of the coil is reduced and the flexibility grows.

Apparent molal volumes and hydration numbers from viscosity studies for microemulsions with a nonionic surfactant derived from castor oil and a series of polar oils

The cloud point of a nonionic surfactant is related to the hydration of its polar shell. Viscosity data can be used to determine the total amount of water associated with micelles. The aim of this study was to apply this model to a more complex system comprising a series of oil-in-water microemulsions. These consisted of the nonionic surfactant, Kolliphor® RH 40, with and without polar oils. The oils used were isopropyl myristate (IPM), neopentyl glycol diethylhexanoate (NGDO), diisopropyl sebacate (DIS) and diisopropyl adipate (DIA) while the alcoholic solvents ethanol, 2-propanol and diethylene glycol monoethyl ether (DEG) were the co-surfactants. The apparent molal volumes were determined from the densities using a pycnometric method while the viscosities were measured using capillary viscometry. The partial excess volumes with IPM ranked as DEG>2-propanol>ethanol while the excess volumes varied as IPM>NGDO>DIS>DIA. These results were most likely related to the effect of the co-surfactant on the size and curvature of the micellar pseudophase and to the site of oil solubilization, respectively. The presence of oil induced increases in the intrinsic viscosities, the Huggins constants and the hydration numbers. The magnitudes of the latter two parameters were in excellent agreement with the values reported for micelles of nonionic surfactants. With DIS, the changes in the hydration numbers showed a good relationship with the excess volumes. Therefore, meaningful hydration values for microemulsions may be obtained with polar oils which are solubilized in the palisade layer rather than in the core as occurs with hydrophobic oils.

Estimation of molecular size of triglyceride in a variety of solvents by using the intrinsic viscosity technique: an important index for transesterification of triglyceride in homogenous system

The effect of solvent type on the molecular size and intermolecular interaction of triglyceride was investigated by the intrinsic viscosity technique. Both the indices may be important for discussing and scrutinizing the behavior of homogeneous transesterification of triglyceride with alcohol since it was found that the co-solvent type influences both the transesterification rate and hydrodynamic size of triglyceride in a homogeneous system. Kinematic viscosity of palm oil dissolved in six different solvents was measured at 298 K by using glass capillary type viscometer to determine the intrinsic viscosity and Huggins constant. By plotting the intrinsic viscosity and Huggins constant against the seven physical properties of the solvents, the polarity of the solvent has been identified as the key factor for molecular size of triglyceride in solution. On the contrary, none of the seven physical properties showed good correlation with the Higgins constant. This may be attributed to more complex nature of the Huggins constant in comparison with the intrinsic viscosity.

Obtaining and Properties of L-Aspartic Acid Solutions of Chitosan

Conditions for obtaining L-aspartic acid solutions of chitosan were considered: dissolution of the polymer with the formation of chitosan aspartate occurs in pH range of 3.6–3.8 at a minimum stoichiometric ratio of [acid]/[chitosan (−NH2)] ∼ 0.43. The hydrodynamic, electrochemical, optical and biological properties of aqueous solutions of chitosan aspartic acid salt are investigated. It has been established that macromolecules of polymeric salt exhibit properties of a polyelectrolyte with a partially compensated charge in an aqueous medium. Huggins constants and temperature viscosity coefficients were calculated, which indicate an increased rigidity of the chitosan macrochain in the studied solutions and deterioration in the polymer—solvent interaction with increasing temperature. Chitosan aspartate powders in the form of lamellar microparticles with fractal ordering were isolated. Low biocompatibility and antibacterial activity of the polymeric salt are demonstrated, which allows recommending the production of biomedical products on its basis.

A new correlation of viscosity and conductivity for the polyelectrolyte solutions of poly(sodium styrene sulphonate) (PSSNa) in N,N-dimethylformamide + water

ABSTRACT The effects of temperature and concentration on the reduced Walden’s law of solutions of poly(sodium styrene sulphonate) (PSSNa) in N,N-dimethylformamide + water (DMF/W) were examined at various temperatures between 20°C and 60°C and concentration levels between 0.1 and 1 g/l. The effects of temperature were described by an Arrhenius-type equation. The intrinsic Walden product [ση] and the Huggins constant of Walden, kση, were calculated and studied. Then, d(ln [ση])/d(1/T) were calculated as the parameter for chain flexibility and molecule conformation. These results showed that the intrinsic Walden’s law product does not decrease linearly with increasing temperature for all concentrations of PSSNa.

Solubility Parameter for Copolymer used Additives for Lubricating Oil

Obiectives: In this article I have been looking at the determination of the solubility parameter by two methods for an additive hydrogenated poly (isoprene-co-styrene) used in lubricating oils. To determine the solubility parameter, it is necessary to know the intrinsic viscosities of the polymer hydrogenated poly (isoprene-co-styrene) in as many solvents with different solubility parameters. Methods: The viscosities of the dilute solutions copolymer hydrogenated poly (isoprene-co-styrene) were determined using Oa and I viscosimeters of the Ubbelodhe Schott capillary-type Viscosimeter set with the 0.04887 and 0.00976 constants at 25°C±0,1°C. From the values obtained for intrinsic viscosities it is concluded that the best solvent for this copolymer is cyclohexane, followed by trichlorethylene, carbon tetrachloride and SAE 10 W oil, and benzene is the weakest. Huggins constants, calculated from the intrinsic viscosity values obtained by extrapolating the reduced viscosities to the zero concentration of the copolymer, have values less than 0.4 for all four solvents. Findings: The value of the overall solubility parameter is comparable to the previous copolymer, which reflects its lack of polarity, and those due to polar interactions and hydrogen bonds are also very small: 1.2 (MPa)1/2 for those obtained by the Hansen method and between 1.4 and 2.4 (MPa)1/2 if the improved one is used. Analyzing the values determined by the two methods it is found that for the partial solubility parameters differences between 0.2 and 1.2 (MPa)1/2 are obtained, due to the intrinsic viscosity intake and the method of determination used. The difference between the global solubility parameters determined by the two methods is 0.4 (MPa)1/2. A larger difference also occurs in the sphere of solubility sphere: the obtained with the improved method is almost 30% lower, which means that fewer solvents are found in the sphere of solubility. The improved method applied to the studied copolymer used as an additive for lubricating oils is much more precise than the Hansen method. The solvents used are mostly included within the scope of the action sphere in the improved method. Application: Determination of the partial and global solubility parameters hydrogenated poly (isoprene-co-styrene) was done, first, using the Hansen method, then by an improved method. The improved method for determining the solubility parameter is much more precise than the Hansen method. Keywords: Additives, Copolymer, Lubricating Oil, Solubility Parameter

PROPERTIES OF DILUTE SOLUTIONS OF COPOLYMERS OF GLYCIDYLMETHACRYLATE AND METHYLPHEOPHORBIDE «a» IN DIMETHYLFORMAMIDE

The study of the rheological properties of polymers, and also the establishment of quantitative dependencies, along with the problem of the relationship of molecular characteristics with the synthesis conditions, is an important scientific and practical task. The solution of this problem gives to predict the behavior of polymers, to develop and find the optimal modes and parameters of obtaining materials with predetermined properties. For a research of chemical interaction between macromolecules in solutions, the dilute solutions rheology of copolymers of glycidylmethacrylate and methylphaeophorbide “a” in dimethylformamide was studied. The study of dilute solutions of the corresponding copolymers was carried out by viscometric method in the temperature range of 20-35 ºC. Copolymers of glycidylmethacrylate and methylphaeophorbide “a” of different composition were obtained by radical copolymerization in solution. The synthesized copolymers are characterized by molecular-weight characteristics determined by gel-permeation chromatography. It is established that the solutions of the copolymers correspond to the systems with the lower critical temperature of dissolution. The belonging of the studied solutions to the systems with the lower critical dissolution temperature is confirmed by the dependence of the Huggins constant on the temperature. From the obtained results it follows that the ball of the macromolecule shrinks with increasing temperature. The influence of solution temperature, molecular weight and composition of copolymers on their interaction with the solvent, expressed quantitatively through the parameters of the characteristic viscosity, the Huggins constant, the mean-square distance between the ends of macromolecular chains, is shown. The mean-square distance between the ends of the chains of polymer in the solution was estimated by the equation of Flory-Fox. It is shown that for the studied copolymers the specific index decreases with increasing temperature. It was determined that the introduction of the porphyrin fragment into the structure of the polymer macromolecule retains the character of the interaction of the macromolecular tangle with the solvent.

Viscometric Determination of the Conformations and Sizes of Polyethylene Glycol Macromolecules in Aqueous Solutions

The kinematic viscosities of solutions of polyethylene glycol (PEG) of different molecular weights (1000, 1500, 3000, 4000, and 6000) are studied at 293.15–323.15 K in the 0–5 g/dL range of concentrations. Parameters are calculated according to the obtained data: characteristic viscosity, the Huggins constant, parameter α in the Kuhn–Mark–Houwink equation, characteristic viscosity in a θ solvent, the coefficient of swelling of the macromolecular coil in solution, root-mean-square distance of PEG macromolecular chain, and the length of Kuhn segments. It is found that the macromolecular coil is partially permeable for the surrounding liquid (water) and opens slightly. It was shown that the PEG molecules shrink as the temperature is raised, as is typical of flexible chain polymers.

Viscometric Study of PC / PEG blends in THF solvent and Gamma-Rays Effect on the Viscosity of PC

In this research the intermolecular interaction between polycarbonate (PC) and polyethyleneglycol (PEG) in tetrahydrofuran (THF) solvent was studied, at 25˚C using a dilute solution viscometry method (DSV).
 The reduced viscosity and intrinsic viscosity and viscosity interaction parameter (b) were experimentally measured, we also discuss the compatility of a polymer mixture in terms of , and the effect of gamma-rays on the reduced viscosity and intrinsic viscosity and Huggins constant of (PC). The results show that the relation between and C is liner within C=(0.9-2)g/dl, and viscometric constant KH decreases with irradiation time while increases with Tirr.

Heat-triggered polymerization of frozen gluten: The micro-morphology and thermal characteristic study

Effect of heating from 25 to 95 °C on the microstructure, surface topography and thermal characteristic of fresh and frozen gluten stored for 30 and 60 d were comparatively investigated. Micro-morphology analysis showed that the size of mesh pores and the molecular height of frozen gluten were greater than the fresh gluten when the temperature exceeded 70 °C. The heat triggered polymerization was weakened for frozen gluten: the particle size and Huggins constant (K’) of frozen gluten were significantly lower than the fresh one upon heating. Thermal analysis revealed that the degradation temperature of frozen gluten protein decreased while its weight loss increased, which reflected the disordered and weak structures in frozen gluten. It was also showed that frozen storage mainly weakened the aggregation ability of protein aggregates (Mw, 130–200 kDa), high molecular weight glutenin subunits (Mw, 75–120 kDa) and α/β-gliadin (28–40 kDa) when the temperature reached 70 °C, as the weakened band intensities were detected for the glutenin-gliadin crosslinkings in the heated frozen gluten compared with that of the fresh gluten.

Hydrodynamic behavior of chitosan hydrochloride macromolecules in aqueous solutions of D- and l-ascorbic acid

The hydrodynamic behavior of chitosan hydrochloride macromolecules in aqueous solutions of D- and l-ascorbic acid in a temperature range 25–45°C was studied by capillary viscometry. The intrinsic viscosity, the Huggins constant, and the temperature coefficient of viscosity were estimated. The effect of the ionic strength of the solvent mixture, predetermined by varying the acid concentration or introducing NaCl, on the hydrodynamic volume of macromolecules and their manifestation of polyelectrolyte properties was revealed. It was established that an increased temperature had led to the macromolecular coils getting more compact and the thermodynamic quality of the water-acid medium as a polymer solvent getting poorer. Despite the close values of pH and ionic strength of the aqueous solutions of D- and l-ascorbic acid, chitosan hydrochloride in the d-ascorbic acid solution is characterized by larger macromolecules and the polymer interaction with the solvent mixture components is energetically more favorable. It is suggested that the conformational state of chitosan hydrochloride is affected not so much by the macrochain stiffness as by the isomeric form of ascorbic acid. A comparison was made of the viscometric parameters of the aqueous solution of the aminopolysaccharide in ascorbic acid with its traditional solvent media, namely: water, acetic and hydrochloric acids, and sodium acetate buffer.

Macromolecular and morphological evolution of hydrophilic polyelectrolyte with N, N-dimethylformamide + water

ABSTRACTThis work aims to establish the influence of the hydrophobic nature of the skeleton on the structure and dynamic properties of polyelectrolytes. Results of comprehensive temperature (T) studies on viscosity of solutions of poly-(sodium styrene sulphonate) (PSSNa) in N, N-dimethylformamide + water (DMF/W) are presented. The reduced dynamic viscosity–temperature relationship has been performed in the Arrhenius temperature domain. The intrinsic dynamic viscosities, the Huggins constant of dynamic viscosity and the indices for chain flexibility and molecule conformation were calculated and studied. The dynamic reduced viscosity–activation energy relationship is established as follows:ηred, exp = ηred) n.arr(E[η]/R) + ηred) arr(E[η]/R). The functions, ηred) n.arr (E [η]/R) represent the non-Arrhenius behaviour of the system and the term of ηred) arr (E [η]/R) is the behaviour of Arrhenius interactions in the mixed . We have also shown that the Huggins constant can be the sum of the Huggins Arrhenius constant (kη, H arr) and the Huggins non-Arrhenius constant (kη, H n.arr).

The Properties of Weak Solutions of N-Vinylpyrrolidone and Methyl Methacrylate Copolymers in Dimethylformamide

The rheology of solutions of N-vinylpyrrolidone and methyl methacrylate copolymers in dimethylformamide in the temperature range 20–35°C was studied. The influence of temperature and of the molecular weight and composition of the copolymers on their interaction with the solvent was shown, expressed quantitatively in terms of intrinsic viscosity, the Huggins constant, and the mean square distance between the ends of the macromolecular chains.

Effect of sodium hydroxide on the interactions of polyethylene glycol macromolecules with water molecules

The rheological properties of dilute water solutions of polyethylene glycols with different molecular mass (1000, 3000, 6000, 8000, 20,000) were investigated in the temperature range 293-323°K in the presence of sodium hydroxide (0.1 mol/l). The intrinsic viscosities, Huggins constants, mean-square distance between the ends of the macromolecular chain, crossover concentrations and activation energies of viscous flow have been determined vs. temperature and molecular mass of polymers. It has been established that the macromolecular coils in the presence of sodium hydroxide (0.1 mol/l) in aqueous solutions of polyethylene glycols accept the unperturbed state as in theta solutions and the intrinsic viscosity becomes very sensitive to the molecular mass of polymers. The new approach for estimating the interaction energy per volume fraction between the macromolecule and solvent molecule has been proposed.

The effect of temperature on the colligative properties of food-grade konjac gum in water solutions.

This research paper presents the results of tests on the colligative properties of konjac gum chains in water solutions. For this purpose, the measurements of osmotic pressure and intrinsic viscosity of aqueous solutions, in the function of konjac gum concentration and temperature were carried out. The applied methods allowed for the determination of the second osmotic virial coefficients B2, which raised with the increase of temperature. It indicate that increase of temperature causes higher affinity of polysaccharide's chains to water. It was determined, that the osmotic average molecular mass of the konjac gum in non-purified solutions increases with temperature (1.07×105-3.80×105g×mol-1). Values of the reduced viscosity linearly increased in range 18-29dL×g for all temperatures. Received values of the Huggins constant (0.81-1.72) lead that water is poor solvent for konjac gum. The theta (θ) conditions were extrapolated for non-purified solutions - 325K (52°C), and interpolated for purified solutions - 307K (34°C). Based on the results of tests using the dynamic light scattering, the values of two main relaxation times (fast - 0.4-1.8ms and slow components - 4300-5500ms) were determined (the Kohlrausch-Williams-Watts). The obtained autocorrelation functions were characteristic for sol type systems or these which indicate a gel-like structure.