• Korea-Australia Rheology Journal
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• 제15권1호
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• pp.27-33
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• 2003

Associating polymers are hydrophilic long-chain molecules to which a small amount of hydrophobic groups (hydrophobes) is incorporated. In aqueous solution, the association interactions result in the formation of three-dimensional network through flowerlike micelles at high concentrations. In colloidal suspensions, the associating polymers act as flocculated by bridging mechanism. The rheological properties of suspensions flocculated by associating polymers end-capped with hydrophobes are studied in relation to the bridging conformation. At low polymer concentrations, the polymer chains effectively form bridges between particles by multichain association. The suspensions are highly flocculated and show typical viscoelastic responses. When the polymer concentration is increased above the absorbance at saturation, the excess polymer chains remaining in the solution phase build up three-dimensional network by associating interactions. Since the presence of particles does not significantly influence the network structures in the medium, the relative viscosity, which gives a measure of the degree of flocculation is decreased with increasing polymer concentration. The bridging conformation and flocculation level vary strongly depending on the polymer concentrations.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.118-119
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• 2006

The characterization method for associating polymer solutions was briefly reviewed. The method has not yet established in comparison with the characterization method for molecularly dispersed polymers in solution. However, two examples of associating polymer systems, living polybutadiene anions and amphiphilic statistical copolymers, were successfully characterized on the basis of suitable model and theory.

• Korea-Australia Rheology Journal
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• 제15권4호
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• pp.179-185
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• 2003

Associating polymers act as flocculants in colloidal suspensions, because the hydrophobic groups (hydrophobes) can adsorb onto particle surfaces and create intermolecular cross-linking. The steady-shear viscosity and dynamic viscoelasticity were measured for suspensions flocculated by multichain bridging of associating polymers. The effects of surfactant on the suspension rheology are studied in relation to the bridging conformation. The surfactant molecule behaves as a displacer and the polymer chains are forced to desorb from the particle surfaces. The overall effect of surfactant is the reduction of suspension viscosity. However, the additions of a small amount of surfactant to suspensions, in which the degree of bridging is low, cause a viscosity increase, although the number of chains forming one bridge is decreased by the forced desorption of associating polymer. Since the polymer chains desorbed from one bridge can form another bridge between bare particles, the bridging density over the system is increased. Therefore, the surfactant adsorption leads to a viscosity increase. The surfactant influences the viscosity in two opposing ways depending on the degree of bridging.

• Macromolecular Research
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• 제10권1호
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• pp.18-23
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• 2002

We theoretically consider blends of two monodisperse one-end-functionalized homopolymers (denoted by A and B) capable of forming clusters between functional groups (stickers) using weak segregation theory. In this model system resulting molecular architectures via clustering resemble star copolymers having many A- and B-arms. Minimizing the total free energy with respect the cluster distribution, the equilibrium distribution of clusters is obtained and used for RPA (Random Phase Approximation) equations as input. For the case that polymers are functionalized by only one kind of sticker, the phase diagrams show that the associations promote the macrophase separation. When there is strong affinity between stickers belonging to the different polymer species, on the other hand, the phase diagram show a suppression of the macrophase separation at the range of high temperature regime, as well as the phase coexistence between a disordered and a mesoscopic phase at the relatively lower temperatures.

• Macromolecular Research
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• 제11권6호
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• pp.444-450
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• 2003

Hydrophobically End-capped polyethylene oxide Urethane Resin(HEUR)-associating polymers, HEUR 35(8), HEUR 35(12), and HEUR 35(18), comprise a polyethylene oxide (PEO) having a molecular weight of 35,000 that is end capped with two C$\_$8/H$\_$17/, C$\_$12/H$\_$25/, and C$\_$18/H$\_$37/ alkyl chains, respectively. These associating polymers were synthesized by condensation reactions with polyethylene oxides and alkyl isocyanates. The self-diffusion coefficients of HEUR-associating polymers were measured in aqueous solution by pulsed-gradient spin-echo (PGSE) nuclear magnetic resonance (NMR) spectroscopy. All polymers underwent a decrease in their mean diffusion coefficients as the concentration was increased. However, the dispersion of the diffusion coefficients, ${\beta}$, about the mean fluctuated with changes in concentration. The large dispersion at low concentrations of HEUR 35(8) and HEUR 35(12) is related to the interaction between hydrophobic end groups, and the large dispersion at high concentrations of HEUR 35(18) is correlated with transient network formation. These results are valuable for predicting the associating mechanism of the large aggregates before and after their critical micelle concentration.

• 폴리머
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• 제39권3호
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• pp.403-411
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• 2015

A series of hydrophobically associating fluorinated amphiphilic polyacrylamide copolymers with remarkably high heat resistance and salt tolerance were synthesized by free radical micellar copolymerization, using acrylamide (AM) and sodium 2-acrylamido-tetradecane sulfonate ($AMC_{14}S$) as amphiphilic monomers, and 2-(perfluorooctyl) ethyl acrylate (PFHEA) as hydrophobic monomer. The structure of the terpolymer was characterized by FTIR, $^1H$ NMR and $^{19}F$ NMR. The solution properties of the terpolymers were investigated in details, and the results showed that the terpolymer solution had strong intermolecular hydrophobic association as the concentration exceeded the critical association concentration 1.5 g/L. The terpolymer solution possessed high surface activity, viscoelasticity, excellent heat resistance, salt tolerance and shearing resistance. The viscosity retention rate of copolymer solution was as high as 59.9% under the condition of fresh wastewater, $85^{\circ}C$ and a 60-days aging test.