Properties of Solutions of Rodlike Chains from Dilute Solutions to the Nematic State

1988 ◽  
Vol 134 ◽  
Author(s):  
Guy C. Berry
Keyword(s):  
Physical Chemistry ◽  
Intrinsic Viscosity ◽  
Rheological Behavior ◽  
Nematic Phase ◽  
Infinite Dilution ◽  
Chain Conformation ◽  
Dilute Solutions ◽  
Concentrated Solutions ◽  
Nematic State ◽  
Rodlike Polymers

ABSTRACTCertain aspects of the physical chemistry of solutions rodlike polymers are reviewed. The range of concentrations includes infinite dilution ([ŋ]c<<l), dilute solutions ([ŋ,]c<l), moderately concentrated solutions (l<[ŋ]c<[ŋ]cNI), and concentrated solutions (c<cN,), where [ŋ] is the intrinsic viscosity and cNI. is the concentration required for a stable nematic phase. Studies of chain conformation are emphasized at infinite dilution, and rheological behavior is emphasized for more concentrated isotropic and nematic solutions. Both theoretical and experimental considerations are included.

Molecular Transformations in DNA under the Influence of UV-radiation

2020 ◽  
Vol 04 ◽  
Author(s):  
Vigen G. Barkhudaryan ◽  
Gayane V. Ananyan ◽  
Nelli H. Karapetyan
Keyword(s):  
Uv Radiation ◽  
Uv Irradiation ◽  
Absorption Spectroscopy ◽  
Calf Thymus Dna ◽  
Dilute Solutions ◽  
Concentrated Solutions ◽  
Buffer Solution ◽  
Low Concentration ◽  
Calf Thymus ◽  
Dna Solutions

Background: The processes of destruction and crosslinking of macromolecules occur simultaneously under the influence of ultraviolet (UV) radiation in synthetic polymers, dry DNA and their concentrated solutions. Objective: The effect of UV radiation on calf thymus DNA in dilute solutions subjected to UV- irradiation was studied in this work. Method: The calf thymus DNA was studied in dilute solutions using viscometry, absorption spectroscopy and electrophoresis. Results: It was shown, that at a low concentration of DNA in the buffer solution ([DNA] = 85 μg / ml) under the influence of UV radiation, the processes of destruction of macromolecules and an increase in their flexibility predominate, which is accompanied by a gradual decrease in the viscosity of their solution. In addition, due to the low concentration of the solution, intramolecular crosslinking of macromolecules predominates, which also reduces their size and, consequently, the viscosity of the solution. Conclusion: It was concluded, that in dilute DNA solutions, due to the predominance of the processes of intramolecular crosslinking of macromolecules over intermolecular, only constant processes of decreasing the sizes of DNA macromolecules occur. As a result, its solubility remains virtually unchanged during UV irradiation. The described comments are also excellently confirmed by the results of absorption spectroscopy and electrophoresis

Molar volumes and refractivities of highly concentrated solutions of ammonium and potassium thiocyanates in water and dimethylsulphoxide

1988 ◽  
Vol 66 (9) ◽  
pp. 2244-2249 ◽  
Author(s):  
Petr Pacák ◽  
Zdenĕk Kodejš
Keyword(s):  
Composition Range ◽  
Apparent Molar Volumes ◽  
Refractive Indices ◽  
Dilute Solutions ◽  
Concentrated Solutions ◽  
Lorenz Equation ◽  
Molar Volumes ◽  
Solvent Interactions ◽  
Density Measurements ◽  
Concentration Dependences

Densities and refractive indices of highly concentrated solutions of ammonium and potassium thiocyanates in water and dimethylsulphoxide have been measured at 333.2 K in the composition range from xs = 0.01 up to saturated solutions. Molar volumes and apparent molar volumes have been calculated from density measurements and their concentration dependences are discussed. All the systems are volumetrically non-ideal and exhibit negative deviations from additivity. The molar refractivities were calculated from the refractive indices using the Lorentz–Lorenz equation. The refractivity values of individual ions were estimated in infinitely dilute solutions and were used for discussion of ion–solvent interactions.

Chain Conformation of Poly(d-lactide) in Tetrahydrofuran by Static Light Scattering, Small-Angle X-ray Scattering, and Intrinsic Viscosity

2020 ◽  
Vol 53 (5) ◽  
pp. 1604-1612 ◽  
Author(s):  
Yoshinori Suzuki ◽  
Takahiro Watanabe ◽  
Hiroki Kosugi ◽  
Kayo Ueda ◽  
Moriya Kikuchi ◽  
...  
Keyword(s):  
Light Scattering ◽  
Intrinsic Viscosity ◽  
Small Angle ◽  
Chain Conformation ◽  
Static Light Scattering ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering

Chain conformation and rheological behavior of exopolysaccharide from Bacillus mucilaginosus SM-01

2017 ◽  
Vol 65 ◽  
pp. 165-174 ◽  
Author(s):  
Li Yu ◽  
Xiaojuan Xu ◽  
Jinping Zhou ◽  
Guozhong Lv ◽  
Jinghua Chen
Keyword(s):  
Rheological Behavior ◽  
Chain Conformation ◽  
Bacillus Mucilaginosus

Synthesis of star hydrophobically-modified acrylamide copolymers and its some properties in brine

e-Polymers ◽  
2012 ◽  
Vol 12 (1) ◽  
Author(s):  
Ming Duan ◽  
Shenwen Fang ◽  
Liehui Zhang
Keyword(s):  
Shear Rate ◽  
Intrinsic Viscosity ◽  
Apparent Viscosity ◽  
Intramolecular Interaction ◽  
Three Dimensional ◽  
Dilute Solutions ◽  
Hydrophobically Modified ◽  
Star Copolymers ◽  
Huggins Constant ◽  
Acrylamide Copolymers

AbstractStar copolymers of acrylamide (AM) and N,N-dimethyl-Nvinylnonadecan- 1- aminium chloride (C18DMAAC) were synthesized by photopolymerization in water. Some properties of these star hydrophobically modified acrylamide copolymers (SHMPAM) with different C18DMAAC contents and the linear hydrophobically modified acrylamide copolymers (LHMPAM) in brine were characterized. The increase in C18DMAAC content resulted in decreased intrinsic viscosity and increased Huggins constant for SHMPAM. Similar results were observed for LHMPAM. With similar intrinsic viscosity and C18DMAAC content, the Huggins constant of SHMPAM was much higher than that of LHMPAM, which might be due to the fact that SHMPAM had much stronger intramolecular interaction in dilute polymer solutions. In semi-dilute solutions, the apparent viscosity of SHMPAM was increased with increasing C18DMAAC content, which was similar to that of LHMPAM. However SHMPAM exhibited higher apparent viscosity than LHMPAM because it had more arms and thus had more chances to form three-dimensional networks in semi-dilute solutions. In the flowinduced scission experiment, SHMPAM exhibited superior shear stability in comparison with LHMPAM. When the extensional shear rate was ≈ 40000 s-1, the reduction ratios of the apparent viscosities of the four SHMPAMs after the scission were about 80%. In contrast, when the extensional shear rate was ≈20000 s-1, the reduction ratio of the apparent viscosity of LHMPAM-0.40 had already reached around 80%.

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