Thermodynamic Quality Of Solvent Research Articles

Synthetic and natural polyampholytes: Structural and behavioral similarity

The ability of synthetic polyampholytes to adopt globular, coil, helix, and stretched conformations and to exhibit coil–globule, helix–coil, liquid–liquid, sol–gel phase transitions with respect to internal (structure, composition, charge distribution, hydrophobicity, hydrophilicity, and so forth) and external factors (pH, temperature, ionic strength, thermodynamic quality of solvents, and so forth) is very important in duplicating the structural hierarchy of proteins. In this review, the structural and behavioral similarities between synthetic and natural polymers are analyzed, primarily concentrating on synthetic polyampholytes, amphoteric polypeptides, and intrinsically disordered proteins (IDPs) in order to demonstrate the close relationship. The application aspects of polyampholytes and future opportunities are briefly outlined.

Hydrodynamic and Conformational Properties of Nitrile-Butadiene Rubbers in Ester Solutions

Dilute solutions of nitrile-butadiene rubbers in toluene, methyl acetate, ethyl acetate, and butyl acetate are studied by viscometry. The rubbers are obtained using paraffinate emulsifiers and contain the same amounts of acrylonitrile and different molecular weights. The effect of rubber molecular weight and solvent nature on the intrinsic viscosity [η], viscometric Huggins k' and Kraemer k'' constants, the hydrodynamic volume of the macromolecule, and the root-mean-square end-to-end distance is estimated. Using these data, laws controlling changes in the thermodynamic quality of solvents with respect to nitrile-butadiene rubbers, which are confirmed by static light scattering measurements, are revealed.

Copolymers of diallyldimethylammonium chloride and 2-(diallyl(methyl) ammonio) acetate: Effect of composition and ionic strength on conformational properties

Copolymerization of diallyldimethylammonium chloride (DADMAC) with 2-(diallyl(methyl) ammonio) acetate (DAMA) was studied. A homologous series of random copolymers (poly(DADMAC-co-DAMA)) with the DADMAC:DAMA ratio equal to 3:7 was investigated by dynamic and static light scattering, viscometry, and flow birefringence in 0.1M NaOH solutions with the addition of NaCl (up to 1M). The Mark-Kuhn-Houwink equations were obtained. It was established that decrease in the concentration of low molecular weight salt leads to sharp increase in thermodynamic quality of solvents, and, therefore, in swelling of the macromolecules. Equilibrium rigidity of the studied copolymer was determined as 5nm. Conformational behavior of poly(DADMAC) (polyelectrolyte), poly(DAMA) (polyzwitterion) and poly(DADMAC-co-DAMA) with the DADMAC:DAMA ratio equal to 3:7 was investigated in solutions at different ionic strength values. It was established that at NaCl concentrations below 0.1M, copolymer exhibits properties typical of polyelectrolyte, and at higher NaCl concentrations it exhibits properties typical of polyzwitterion. Detailed consideration of contributions of optical effects of micro- and macroform to the observed flow birefringence in copolymer solutions allowed us to estimate optical characteristics of copolymer macromolecules. It was established that in salt-free aqueous solution, poly(DADMAC-co-DAMA) macromolecular coils swell isotropically.

Surface properties of poly(styrene-co-n-butyl acrylate) binary copolymers: Effect of chain microstructure and composition

The regularities of changing of surface energy characteristics of poly(styrene-co-n-butyl acrylate) binary copolymers films at varying of chain microstructure, composition and thermodynamic quality of solvent, from which films are formed, with respect to comonomers, were detected. The concordance between the information about characteristics of films surfaces, obtained via contact angle measurements and ATR-FTIR spectroscopy was observed. The type of polymer chain microstructure, provided the best adhesion properties of copolymers with respect to polar phases was detected.

Spectroscopic and viscometric studies on the interaction of ionic liquid, 1-butyl-3-methylimidazolium bromide with polyvinyl pyrrolidone

Polyvinyl pyrrolidone, a nontoxic biocompatible polymer, has broad applications in pharmacy, cosmetics, and detergent industry. Although PVP is easily soluble in water, some recent findings indicate that water is not a thermodynamically good solvent for PVP. In this research, interaction of PVP with 1-butyl-3-methylimidazolium bromide ionic liquid was studied via FT-IR, UV–vis and viscometric methods. The flow activation energies were found from the linearization of Arrhenius equation and correlated in terms of polymer concentration. Thermodynamic quality of solvent was investigated using the sign of initial slope of the activation energy versus polymer concentration at zero concentration. For this purpose, viscosity and density of polyvinyl pyrrolidone in aqueous solution of ionic liquid at the temperature range of 288.15–313.15K were measured. Results suggested that the thermodynamic quality of water is increased by addition of 1-butyl-3-methylimidazolium bromide in aqueous solution of polyvinyl pyrrolidone.

Fourier-transform infrared spectroscopic study of a fractional-complexed polymer blend

FTIR spectroscopy and quantum chemical calculations have been used to explore the system of high-molecular mass pair of miscible polymers poly(N-methyldodecano-12-lactam) (PMDL) and poly(4-vinylphenol) (PVPh) in tetrahydrofuran (THF) that is known to undergo associative phase separation into a gel-like interpolymer complex and a soluble residual phase (RP). Using quantum chemical calculations, two types of hydrogen bonding interactions involving the CO group of PMDL and either one or two OH groups of PVPh were identified in the FTIR spectra of both the complex and RP. Although relatively small differences were found between the FTIR spectra of the complex and RP, detailed analysis of the CO stretching region revealed that in the complex, the stronger H-bonding interactions of the CO groups with two OH groups slightly outnumbered those in RP. In addition, a proof was added to the recent claim that fractionation accompanied the process of H-bond formation and complex precipitation but did not precede it. Finally, it was suggested that change in thermodynamic quality of solvent took place due to the complexation of the two polymers; the complex stability in a polar proton-donating solvent was tested as well.

Effect of temperature and thermodynamic quality of solvent over unperturbed chain dimensions of nylon 6

AbstractA nylon 6 sample having average molecular mass 4.825 × 105 g mol−1 was fractionated into five different fractions with respect to molecular mass, which ranged from 3691 to 999,000 g mol−1. The light scattering and intrinsic viscosity measurements were made in m‐cresol and its mixture with 1,4‐dioxane. The second virial coefficient, radius of gyration and Mark Houwink's constant and unperturbed chain dimensions were determined by light scattering and viscosity measurement. It has been observed that all these parameters are composition of solvent and temperature dependent. The solvent having composition of 97% m‐cresol and 3% dioxane, was best and it deteriorated with the increase/decrease in percentage of 1,4‐dioxane in m‐cresol. However, its thermodynamic quality was enhanced with the temperature. Such variation in quality of solvent was reflected in all the estimated parameters and showed maxima at this composition of solvent. The unperturbed dimensions obtained by different methods though, differed in values but showed same trend and NA‐MKB method gave close results to the one obtained through [ηo]. A new expression has also been proposed relating ko to solvent quality and temperature and the data obtained by us for nylon‐6 and the one obtained from the literature for dextran obeyed this expression up to large extent irrespective of the solvent composition and temperature. The proposed equations have also been applied to dextran/methoxy ethylene and dextran/ethylene glycol systems and worked well. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.

Preparation and Characterization of Novel Polymeric Betaines Based on Aminocrotonates

This review summarizes the preparation and physico‐chemical properties of novel polymeric betaines based on ethyl 3‐aminocrotonate and its N‐substituted alkyl derivatives that, in turn, were obtained by condensation of acetoacetic ester with various amines, aminoalcohols, and aminoacids in mild conditions. Stereochemical peculiarities and tautomeric transitions in monomers as well as kinetics and mechanism of formation of linear and crosslinked polybetaines proceeding via Michael addition reaction are outlined. Attention was paid to hydrodynamic, conformational and molecular characteristics of linear and stimuli‐sensitive properties of crosslinked systems as a function of pH, ionic strength, thermodynamic quality of solvents and electric field.

SOLVENT QUALITY AND SOLUTION BEHAVIOR OF NYLON 12

The refractive index increment, dynamic and static laser light scattering, intrinsic viscosity [η] and Huggins constant (KH) of nylon 12 have been measured in m-cresol and sulphuric acid/water system at 10–60°C. The intrinsic viscosity, RH, Rg, A2, and ( 2)1/2 (calculated from viscosity data) and "a" values of nylon 12 are found to be higher in m-cresol than in sulphuric acid. All these parameters decrease with the increase in water contents in sulphuric acid. The refractive index increment, KH and activation energy show an opposite trend to that of [η]. The intrinsic viscosity, RH, Rg, A2, and ( 2)1/2 have maximum values around 30–40°C in sulphuric acid/water system, whereas in m-cresol they fall at about 20°C. It has been concluded that the variation in size, interaction parameter (second virial coefficient), [η] and KH of the polymer solutions with the alteration in solvent composition and temperature are the out come of change in thermodynamic quality of solvents, selective adsorption, hydrogen bonding and conformational transitions. It has also been concluded that the increase in temperature first enhances the quality of the solvent, encourages hydrogen bonding and specific adsorption, and then deteriorates, bringing conformational transitions in the polymer molecules. However, the addition of water to sulphuric acid continuously deteriorates the solvent quality. This characteristic of the solvent system brings conformational changes in the polymer especially at low temperatures.

Interaction of richlocain with some linear and crosslinked polymers

The interaction of local anesthetic drug richlocain with linear polyacrylic acid and crosslinked sodium polyacrylate, linear and crosslinked acrylic acid–Schiff base copolymers has been investigated. The compositions of forming polymer–drug complexes were determined. The influence of external factors such as pH, ionic strength, temperature and thermodynamic quality of solvent on the stability of these complexes was studied. The kinetics and activation energy of drug release from the gel matrix has been evaluated.

STUDY OF POLYSTYRENE-BLOCK-POLY(METHYLMETHACRYLATE) MICELLES BY SEC/MALS. DETERMINATION OF MOLECULAR WEIGHTS AND SIZE DISTRIBUTION

Polystyrene-block-poly(methyl methacrylate) micelles in 1,4-dioxane/cyclohexane were studied by size exclusion chromatography coupled with multi angle light scattering (SEC/MALS). A sufficient unimer — micelles resolution achieved by SEC made it possible to use MALS detector for the direct determination of distributions and corresponding averages of molecular weights and gyration radii of micelles. Contrary to the standard static light scattering approach,the SEC/MALS technique provided these averages in one analytic run with a minimum amount of copolymer sample. In most systems, very narrow molecular weights and size distributions of micelles were obtained. For a given copolymer, the micellar association number increased with decreasing thermodynamic quality of solvent. Under given thermodynamic conditions, it increased with increasing length of insoluble poly(methyl methacrylate) block and with decreasing length of soluble polystyrene block. The micellar radius of gyration was predominantly controlled by the molecular weight of the copolymer.

Porous materials from crystallizable polyolefins produced by gel technology

AbstractA new method for obtaining porous and porous fiber polymers is presented. This method is based on using gel‐type technology (without previously preparing polymer solutions) for crystallizable polymers, preparing polyethylenes, and including polyethylenes of very high molecular mass and isotactic polypropylene. The method consists in swelling crystalline polymer films at elevated temperatures in a proper solvent with subsequent precipitation with a non‐solvent at different conditions. In this case, simultaneous or consecutive processes of phase separation of amorphous or/and crystalline type occurs; stretching the sample can also accompany this process. Complete phase diagrams of two‐ and three‐component systems (polymer‐solvent and polymer‐solvent precipitator) were constructed. Temperature‐concentration boundaries of amorphous separartion (binodal) and crystallization (liquidus) are reported for the system polyethyleneo‐xylenedimethyl formamide. Phase transitions of both types influence characteristics of the resultant porous structure. They were prepared by simultaneous (precipitation of a gel by dimethyl formamide at 25°C) or consecutive (precipitation with a hot non‐solvent at 138°C and following cooling) phase separation. Studied were the effect of experimental conditions (temperature, times for solvation and precipitation, polymer molecular mass, the thermodynamic quality of solvents and parameters of film stretching) on peculiarities of the structure and quantitative characteristics of final porous and fiber‐porous polyolefins. It has been demonstrated that the method proposed allows us to obtain a crystalline and highly porous polymer with open poros, a bimodal size distribution and with a highly developed inner surface. Further high strength and small shrinkage are characteristic of the fiber‐porous materials. The method under discussion appears to be universal, it does not require a preliminary preparation of polymer solutions and can be realized within a general technology of polymer films and sheet processing. Highly porous polymers obtained by this technology, primarily based on polyethylenes of very high molecular mass, can be used as neutral supports for multi‐functional membranes, polymeric covers, frame systems for implants and other applications.

Study of Polystyrene-Block-Poly(Methyl Methacrylate) Micelles by Size Exclusion Chromatography/Low Angle Laser Light Scattering. Influence of Copolymer Composition and Molecular Weight

Abstract Results of size exclusion chromatography study of the micellar systems polystyrene-block-poly(methyl methacrylate) in the mixed solvent 1,4-dioxane/cyclohexane are reported and the behaviour of copolymers with different overall molecular weight and chemical composition is compared. At higher content of cyclohexane, the effect of the solute trapping in the column due to the adsorption of the unimer on the packing was observed. This effect was more pronounced for the lower molecular-weight copolymers as compared with the higher molecular-weight ones and was found to depend significantly on the thermodynamic quality of solvent (eluent). Experiments in 1,4-dioxane/70 vol.% cyclohexane showed strong influence of unimer—micelles re-equilibration in the column on the resulting chromatograms, especially for the micellar systems of the lower molecular-weight copolymers. For the copolymers of higher molecular-weight, the micelles dissociation in the column was reduced probably due to the more entangled and compact cores of micelles.

On Multi-valued Surface Properties of PMMA Films

Abstract An apparent link between the surface properties of polar group-containing polymers, such as PMMA and Styrene/Acrylic copolymers, and the thermodynamic quality of solvents used in solutions from which the polymers were cast, was described in earlier papers.1,2 In these polymers, significant variations have been observed in critical surface tensions(γc), and in the thermodynamic interaction parameters for selected vapor-polymer pairs, when the configuration of the polymer in solution was varied through the suitable selection of solvents of differing thermodynamic quality. The “solvent history” effect on surface properties of solid film was not detected however for non-polar polymers such as polystyrene (PS).1,2 Apparently the distinct chain configurations adopted in solution by PMMA are carried over into the solid and result in different proportions of non-polar (backbone) and polar (side chain) moieties being located in the surface layer of the solid. Since only one surface state can correspond to...

Investigation of the conditions of negative thixotropy of poly(methyl methacrylate) solutions in low-viscosity solvents. I. Influence of polymer concentration, temperature and thermodynamic quality of solvent

Investigation of the conditions of negative thixotropy of poly(methyl methacrylate) solutions in low-viscosity solvents. I. Influence of polymer concentration, temperature and thermodynamic quality of solvent