Solution properties of ultrahigh molecular weight polymers. 12. Systematic error sources affecting the discussion of the excluded volume effect

Ioan, Silvia; Leonte, A.; Sava, Constanta; Simionescu, B. C.; Simionescu, C. I.

doi:10.1002/actp.1986.010370901

Cited by 6 publications

(2 citation statements)

References 19 publications

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“…This equation has been found to work exceptionally well for concentrated polymer solutions where the concentration of the solution passes into the semidilute regime, and the polymer chains are overlapping. For example, Ioan et al have found that Fedors equation is very effective at calculating the intrinsic viscosity of dilute to moderately concentrated high molecular weight poly(butyl methacrylate) polymer solutions . In addition, Ghimici et al have found that Fedor's equation does a better job of calculating the intrinsic viscosity of hydrophobically modified polyelectrolytes than Fuoss's equation. , Fedors equation was applied to the linear-dendritic rod diblock copolymer systems that exhibited an upward curvature in the Huggins and Kramer equations, and it gave a very strong linear correlation.…”

Section: Resultsmentioning

confidence: 99%

Solution Behavior of Linear-Dendritic Rod Diblock Copolymers in Methanol

2006

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The solution behavior of spherical dendrimers as well as hybrid-linear dendritic diblock copolymers has been extensively studied, and the size, shape, and ability of these polymers to encapsulate small molecules have led to their comparison with traditional micelles. We have recently reported the synthesis of a new dendritic copolymer architecture, the linear-dendritic rod diblock copolymer, and in this work, we examine the solution behavior of these unique polymers in methanol at 25 degrees C, using dynamic light scattering and intrinsic viscosity measurements. The diblock copolymers consist of a linear poly(ethylene oxide)-poly(ethylene imine) diblock copolymer backbone around which poly(amido amine) branches have been divergently synthesized from the poly(ethylene imine) block. The hydrodynamic radii and the viscometric radii of the polymers were found to increase slowly with increasing generation up to generation 3.5; however, after generation 3.5, the radii were found to increase very rapidly. This increase can be explained by an elongation of the dendritic block into a more rodlike configuration and a corresponding breakdown of the spherical approximation used to calculate the radii. The intrinsic viscosity of the amine and ester terminated polymers was found to follow two very different trends at low generation; however, at higher generations, they followed similar, yet slightly different, curves with the values for the amine terminated polymers only a little larger than those of the ester terminated polymers. At low generations, the chemistry of the end groups and its interaction with the solvent were found to be more important, whereas at higher generations, the highly branched nature of the dendritic block was the more important factor. For the ester terminated polymers, a maximum in the intrinsic viscosity occurred at generation 1.5. Since this maximum occurred at a much lower generation number than is traditionally seen for spherical dendrimers, new scaling relations for the intrinsic viscosity of dendritic rod polymers were developed and were found to support this observation. A minimum in the intrinsic viscosity was also observed at generation 3.5 for the ester terminated polymers and a minimum or leveling off in the intrinsic viscosity at generation 4.0 was found for the amine terminated polymers, which can be attributed to the transitioning of the polymers to a more elongated, rodlike shape and the increased influence of the shape factor on the intrinsic viscosity.

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Section: Resultsmentioning

confidence: 99%

Solution Behavior of Linear-Dendritic Rod Diblock Copolymers in Methanol

2006

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“…This equation was more appropriate for the analysis of these systems than the Martin or Schulz-Blaschke models, which are widely used for describing the viscosity of nonionic and anionic cellulose ethers. The equation proposed by Fedors, which takes into account the increase of the reduced viscosity at very low concentrations of polyelectrolyte, has been successfully applied to very different polyelectrolyte dispersions such as butyl methacrylate 33 and cationic polyethylenglycols. 29 The markedly higher intrinsic viscosity of PQ-10 suggests that these two polymers present important differences in molecular weight.…”

Section: Properties Of the Cationic Celluloses Tablementioning

confidence: 99%

Rheological Evaluation of the Interactions between Cationic Celluloses and Carbopol 974P in Water

Rodrı́guez

Alvarez‐Lorenzo

2001

Biomacromolecules

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This paper reports on the influence of the structural properties of two cationic hydroxyethylecelluloses, polyquaternium-4 (PQ-4; 1.13-1.27% N) and polyquaternium-10 (PQ-10; 1.88-1.95% N), on the rheological behavior of their dispersions and of the dispersions of their blends with Carbopol 974P (60.9% COOH) in water. Dynamic shear oscillation measurements showed that the rheological behavior of 1 and 2% (w/w) cellulose polymers was mainly viscous. Flow curves of PQ-10 dispersions presented a higher consistency and pseudoplasticity than PQ-4 dispersions, in which the thixotropy was higher. Structural features, such as type and distribution of substituents and molecular weight, explain why they behave different. The presence of 0.00125-0.02% Carbopol in diluted cationic cellulose (0.01-0.08%) dispersions produced an important decrease in viscosity, due to a strong associative process via an electrostatic interaction phenomenon. Similar results were obtained when sodium acetate was added instead of Carbopol. In contrast, in the concentrated range (1% cellulose polymer), the viscous (G") and especially the elastic (G') moduli of the dispersions increased monotonically with Carbopol concentration (0.010-0.125%) and became physical gels, except in the proximity of the neutralization of the ammonium groups (0.07% Carbopol for PQ-4, and 0.1% Carbopol for PQ-10) in which G" and G' decreased. The concentrated dispersions showed pH-sensitivity when the Carbopol added was around or above the neutralization point. In dispersions with this composition, consistency increased dramatically when pH changed from 4.5 to 7.4. This property can open a wide range of applications, especially in the pharmaceutical field to prepare gelling in situ systems.

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Molecular weight investigation of ultrahigh molecular weight poly(butyl methacrylate) by electron microscopy

Simionescu¹,

Ioanid²,

Simionescu³

1987

Acta Polymerica

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Acta Polymerica 38 (1987) Nr. 10 586 ~ 47.7 SIMIONESCU, IOANID and SIMIONESCU: Molecular weight investigation of ultrahigh molecular weight poly(buty1 methacrylate) Tabelle I. pi]und Z,,-TYerte uon Poly(ethyZentcrephthuZat(40)co-osybenzoaten (60) ) hl (in ml/g) HUGGINS I SCHULZ-BLASCHKE B,, .lo-3 28,2 38,2 47,l 51,3 57,8 85,2 94,4 99,4 52;l 58,5 85,4 94,3 99,6 3,8 6 2 6 4 ll,o 11,4 20,3 22,9 23,7 Die Bestimmung der Molmasse der Copolyester erfolgt in Abhangigkeit von ihrem Wert dampfdruckosmometrisch in Hexafluorisopropanol bzw. membranosmometrisch in dem Losungsmittelgemisch Phenol(l)/Tetrachlorethan(l) bei 65% Messungen in m-Kresol weisen infolge von Loslichkeitsproblcmen groficre Unsicherheiten auf. Viskositats-Molmassen-ReziehungIn Phenol(l)/Tetrachlorethan(l) konnte [q] fur Poly(ethy1enterephthalat(40)-co-oxybenzoat(60)) sowohl nach HUGGINS als auch nach SCHULZ und BLASCHKE ermittelt werden. BeidcExtrapolationen ergaben praktisch gleiche [q]-Werte (Tabelle I). Ausgenommen die beiden niedermolelcularen Proben mit [q]gleich 28,2 und 38,2 ml/g wies die HUGGINS-Konstante niit

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Solution properties of ultrahigh molecular weight polymers. 12. Systematic error sources affecting the discussion of the excluded volume effect

Cited by 6 publications

References 19 publications

Solution Behavior of Linear-Dendritic Rod Diblock Copolymers in Methanol

Solution Behavior of Linear-Dendritic Rod Diblock Copolymers in Methanol

Rheological Evaluation of the Interactions between Cationic Celluloses and Carbopol 974P in Water

Molecular weight investigation of ultrahigh molecular weight poly(butyl methacrylate) by electron microscopy

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