Viscometric Study of Poly(dimethylsiloxaneb-N-vinylpyrrolidone) in Water Solutions

Abstract

The synthesis and viscometric behavior of poly(dimethylsiloxane-b- N-vinylpyrrolidone) in dilute to extremely dilute water solutions was investigated. The viscometric molecular weights, intrinsic viscosities and critical concentrations which separate the dilute-semi-dilute and dilute-extremely dilute regimes were studied. A dependence between reduced viscosity ηsp /c and concentration for extremely dilute regime was found. The deviation from Huggins dependence is discussed.

Concentration regimes and denaturation effects on the conformational changes of α-chymotrypsin by viscosity and dynamic light scattering measurements

“…On the other hand, the presence of the extremely dilute regime was also confirmed using the dynamic light scattering measurements from the characterization of the conformational changes for various concentrations [22][23][24][25].…”

“…Beside, it is reported that the viscosity measurements showed the presence of anomalies in the viscosity behaviour [16][17][18][19][20][21]. These anomalies are attributed to the adsorption of the sample onto the wall of the capillary and to the change of the real magnitude of molecules below a certain critical concentration [22][23][24][25]. Therefore, the presence of anomalies is contributed to the extremely dilute solution when we consider it as the fourth regime of concentration [16][17][18][19][20][21].…”

“…The enzyme, which contains 9% helix and 34% ␤-sheet, consists of a single polypeptide chain of 245 amino acid residues cross-linked by five disulfide bonds [22,[40][41][42]. ␣-Chymotrypsin type from bovine pancreas (EC 3.4.21.1) was purchased from Sigma-Aldrich and used without further purification.…”

Ceria loaded nanoreactors: a nontoxic superantioxidant system with high stability and efficacy

“…4,4′-Azobis(4-cyanovaleryl) chloride was synthesized by the reaction of 4,4′-azobiscyanopentanoic acid previously dried by azeotropic distillation from toluene, with phosphorus pentachloride (PCl 5 ) according to the method reported in the literature 39 (Sigma-Aldrich). 1-Vinyl-2-pyrrolidinone (Sigma-Aldrich) was purified before use by vacuum distillation and kept under N 2 .…”

Properties of Some Poly(siloxane)s for Optical Applications

“…In previous papers [8,[11][12][13][14][15] the synthesis, structural and conformational characterization of some poly(siloxane)s, as well as poly(siloxane-azomethine)s, poly(dimethylsiloxane-b-N-vinylpyrrolidone)s, poly(vinyl-g-dimethylsiloxane)s, and segmented poly (ester-siloxane)-urethane have been described and the characteristics of each of the abovementioned polymers have been discussed.…”