Fluorescence Probe Studies of Poly(Acrylic Acid) Interchain Complexation and Chain Rigidity Indyced by High Shear Flow. Influence of Molecular Environment

1991 ◽  
Vol 248 ◽  
Author(s):  
Oh-Kit Kim ◽  
Ling-Siu Choi

AbstractThe mode and strength of poly(acrylic acid), PAA, interchain complexation was strongly influenced by the presence of salts and cationic surfactants. Addition of salts to the shearing PAA solution disrupted the complexation, while modification of the PAA with surfactant enhanced the complexation but only below a critical concentration that depended on the surfactant chain length and pH employed. The chain morphology developed by such interchain complexation of PAA is a rigid rod-like chain cluster. The PAA self-complexation in the presence of poly(ethylene oxide), PEO, is strongly affected by pH and PEO molecular weight. With a high molecular weight PEO, the PAA self-complexation is drastically suppressed, whereas the PAA complexation and thus, the chain rigidity is markedly enhanced in the presence of a low molecular weight PEO, probably due to physical crosslinking of the PEO between the elongated PAA molecules.

2005 ◽  
Vol 2 (3) ◽  
pp. 212-219 ◽  
Author(s):  
S. Moulay ◽  
M. Boukherissa ◽  
F. Abdoune ◽  
F. Z. Benabdelmoumene

2015 ◽  
Vol 60 (2) ◽  
pp. 1561-1564
Author(s):  
E.-H. Lee ◽  
K.-M. Kim ◽  
W.-Y. Maeng ◽  
D.-H. Hur

Abstract After preparing aqueous suspensions from magnetite particles with a poly-acrylic acid, we investigated the effects of several experimental parameters. We characterized the stability of the suspensions using visual inspection, sedimentation, adsorption, and thermal stability of the dispersant. The dispersion stability is affected by the solution pH, the concentrations of magnetite particles, the molecular weight, the concentration of the dispersants, and the temperature. The stability of the suspensions increased as the concentration of the dispersant and the temperature increased. In terms of the molecular weights of the dispersant, the suspensions with dispersant of low-molecular weight (1800) were more stable than those of high-molecular weight (250000) at room temperature. However, at high temperature the suspensions with high-molecular weight showed stability. The adsorption efficiency of the dispersant was very low. The dispersant of high-molecular weight showed a higher thermal integrity than that of low-molecular weight. From this work, we obtained the optimum conditions for stable aqueous suspensions of magnetite particles.


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