Association of Telechelic Ionomers in Apolar Solvents

Chassenieux, Christophe; Nicolai, Taco; Tassin, Jean-François; Durand, Dominique; Gohy, Jean‐François; Jérôme, Robert

doi:10.1002/1521-3927(20011001)22:15<1216::aid-marc1216>3.0.co;2-o

Cited by 19 publications

(21 citation statements)

References 45 publications

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“…As shown in Figure 3A, when the polymer concentration is 1.0 g/L, which is much greater than the cac cis and cac trans of the polymer, the solution only shows a single fast relaxation mode, which should represent the individual micelles in the solution. 33,34 As the concentration increases to 3.0 g/L, a slow relaxation mode is observed besides the fast mode. The slow relaxation mode should be attributed to the aggregates of micelle according to an open association mechanism suggested by Chasssenieux et al 33,34 When further increasing C, the peak of the slow relaxation mode broadens, indicating the formation of more and larger micellar aggregates.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…33,34 As the concentration increases to 3.0 g/L, a slow relaxation mode is observed besides the fast mode. The slow relaxation mode should be attributed to the aggregates of micelle according to an open association mechanism suggested by Chasssenieux et al 33,34 When further increasing C, the peak of the slow relaxation mode broadens, indicating the formation of more and larger micellar aggregates. After irradiation by UV light, the peak of the slow relaxation mode corresponding to the micellar aggregates becomes narrow ( Figure 3B).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…According to previous researches, HEUR aqueous solution has the same aggregation behavior and association mechanism over a very broad range of concentrations. 8,34 As a result, the origin of decrease in fluctuation time is the same as the decrease in relaxation time in rheological measurements. Thus, bridge− loop transition or loop−bridge transition will occur in the concentrated solution, and rheological response may be observed.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Aggregation and Rheology of an Azobenzene-Functionalized Hydrophobically Modified Ethoxylated Urethane in Aqueous Solution

Ren

Chang

et al. 2016

Macromolecules

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Hydrophobically modified ethoxylated urethanes (HEURs) belong to an important class of telechelic associative polymers for improving solution rheological properties. We designed and prepared a novel azobenzene end-functionalized HEUR polymer (AzoHEUR), which was used to investigate the effects of hydrophobicity change of end hydrophobes induced by photoisomerization of azobenzene on the solution aggregation and rheological properties. The concentrated AzoHEUR solutions show a reversible rheological property change upon alternative exposure to UV and visible light. We have demonstrated that a reversible change in hydrophilic−lipophilic balance of polymer followed by photoisomerization of azobenzene induces a reversible rearrangement of micellar junctions through loop−bridge or bridge−loop transitions, which reversibly changes not only the network connectivity but also the solution relaxation behavior. Moreover, a structural model is proposed to describe the rearrangement of micellar junctions induced by photoisomerization of azobenzene. The work will not only provide new insights into the effect of hydrophobicity change of stimuli-responsive end groups on the aggregation and rheological behavior of HEUR aqueous solutions but also open a new perspective for development of some special applications of HEURs in fabrication and transmission of soft materials, medicines, cosmetics, inks for inkjet printers, and flow rate controlling systems. ■ INTRODUCTIONThe hydrophobically modified ethoxylated urethanes (HEURs) as a representative class of associative polymers have been widely used as thickeners in many fields in which careful control of the rheology of the solution is required, such as water-borne coatings, inks, medicines, and cosmetics over the past decades. 1 Like telechelic amphiphilic polymers, HEURs in aqueous solution can form flowerlike micelles composed of the flower loops (hydrophilic backbone) and the micellar cores (hydrophobic end groups) above a critical aggregation concentration (cac). When the polymer concentration (C) exceeds a critical percolation concentration (C p ), the extra hydrophobic end groups will come into the micellar cores through the bridge connection of the hydrophilic chains to form large aggregates of micelle, and a dynamical physical network of micellar junctions is formed eventually, leading to the solution viscosity rises sharply with increasing C. 2−6 Usually, HEUR aqueous solution possesses a Newtonian plateau at low shear rates, followed by shear thinning at high shear rates, with shear thickening at intermediate shear rates for some samples. The research interests include the mechanism of association, the association structure of the polymer in solution, and the response of this structure under shear stress.Up to now, a lot of theories or models have been developed to describe the aggregation and rheological behavior of HEUR aqueous solution, such as the loop−bridge model developed by Winnik 7,8 and the transient network theory developed by Tanaka and Edward et al. 3,9 Accord...

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

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Aggregation and Rheology of an Azobenzene-Functionalized Hydrophobically Modified Ethoxylated Urethane in Aqueous Solution

Ren

Chang

et al. 2016

Macromolecules

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“…Experiments that investigate the association behavior of multiblock copolymers in dilute, apolar organic solutions are limited. [63][64][65] An example is the work by Nie and et al 65 that studied the structure and dynamics of a polystyrene ͑PS͒polybutadiene ͑PB͒ pentablock copolymer ͑S-B-S-B-S͒ in heptane, a strongly selective solvent for PB and a poor solvent for PS. In dilute solutions, no micellization of the pentablock was detected.…”

Section: A Macro-versus Microphase Separationmentioning

confidence: 99%

Phase behavior and structure formation in linear multiblock copolymer solutions by Monte Carlo simulation

Gindy

Prud'homme²,

Panagiotopoulos³

2008

The Journal of Chemical Physics

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The solution phase behavior of short, strictly alternating multiblock copolymers of type (A(n)B(n))(m) was studied using lattice Monte Carlo simulations. The polymer molecules were modeled as flexible chains in a monomeric solvent selective for block type A. The degree of block polymerization n and the number of diblock units per chain m were treated as variables. We show that within the regime of parameters accessible to our study, the thermodynamic phase transition type is dependent on the ratio of m / n. The simulations show microscopic phase separation into roughly spherical aggregates for m / n ratios less than a critical value and first-order macroscopic precipitation otherwise. In general, increasing m at fixed n, or n at fixed m, promotes the tendency toward macroscopic phase precipitation. The enthalpic driving force of phase change is found to universally scale with chain length for all multiblock systems considered and is independent of the existence of a true phase transition. For aggregate forming systems at low amphiphile concentrations, multiblock chains are shown to self-assemble into intramolecular, multichain clusters. Predictions for microstructural dimensions, including critical micelle concentration, equilibrium size, shape, aggregation parameters, and density distributions, are provided. At increasing amphiphile density, interaggregate bridging is shown to result in the formation of networked structures, leading to an eventual solution-gel transition. The gel is swollen and consists of highly interconnected aggregates of approximately spherical morphology. Qualitative agreement is found between experimentally observed physical property changes and phase transitions predicted by simulations. Thus, a potential application of the simulations is the design of multiblock copolymer systems which can be optimized with regard to solution phase behavior and ultimately physical and mechanical properties.

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“…Associative polymers (APs) containing hydrophobic and hydrophilic segments have a tendency to associate with each other to form physical network structures in aqueous solution. − Consequently, APs have been widely used for conveying useful rheological properties to solutions, such as gelation, increasing viscosity, providing shear-thinning, and thickening in aqueous media. − Telechelic associative polymers (TAPs), consisting of hydrophilic backbone and two hydrophobic end groups, are a class of representative triblock APs and can form so-called flower micelles composed of coronas (hydrophilic backbone) and cores (hydrophobic end groups) above a critical micelle concentration ( cmc ). With the increase of the solution concentration, some hydrophobic end groups will individually attach into neighboring micelles by hydrophobic association.…”

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confidence: 99%

Linear Alternating Associative Polymer with Ultrahigh Molecular Weight: Facile Preparation by Self-Assembly Assisted Dimerization of Anthracene and Rheology in Aqueous Solution

Shan

Luo

et al. 2019

ACS Macro Lett.

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Alternating associative polymers (AAPs) containing more than two species of alternating hydrophobic and hydrophilic units can form unique physical network and perform interesting rheological behavior in aqueous solution. In this work, an AAP was prepared through self-assembly assisted dimerization of an anthracene-functionalized telechelic associative polymer (AnTAP) in aqueous solution by light irradiation. It is demonstrated that AnTAP can in situ chain extend to AAP with well-defined linear structure and ultrahigh molecular weight through dimerization reaction of anthracene moieties in the core of micelle under light irradiation. Meanwhile, the solution changes from viscoelastic liquid to a free-standing gel, because a physical network that cannot relax in a finite time window has developed along with the dimerization process. The results are therefore of interest not only for understanding the network structure and rheological properties of AAP solution, but also for preparing AAPs with ultrahigh molecular weight by self-assembly assisted photodimerization reactions.

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Association of Telechelic Ionomers in Apolar Solvents

Cited by 19 publications

References 45 publications

Aggregation and Rheology of an Azobenzene-Functionalized Hydrophobically Modified Ethoxylated Urethane in Aqueous Solution

Aggregation and Rheology of an Azobenzene-Functionalized Hydrophobically Modified Ethoxylated Urethane in Aqueous Solution

Phase behavior and structure formation in linear multiblock copolymer solutions by Monte Carlo simulation

Linear Alternating Associative Polymer with Ultrahigh Molecular Weight: Facile Preparation by Self-Assembly Assisted Dimerization of Anthracene and Rheology in Aqueous Solution

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