Photoinduced charge separation by chromophores encapsulated in the hydrophobic compartment of amphiphilic polyelectrolytes with various aliphatic hydrocarbons

Morishima, Yotaro; Tominaga, Yoshio; Kamachi, Mikiharu; Okada, Tadashi; Hirata, Yoshihiro; Mataga, Noboru

doi:10.1021/j100168a058

Cited by 86 publications

(93 citation statements)

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“…As we previously reported, 35 the distribution of AMPS, dodecyl, and pyrenyl units in the polymer chain of PyDod-PAMPS is completely random. Accordingly, in the case of PyPAMPS with 2.5 mol % dodecyl content, for example, each pyrene label should have a closest-neighboring dodecyl group within 20 AMPS units apart (ca.…”

Section: Discussionsupporting

confidence: 61%

Interaction of Pyrene-Labeled Hydrophobically Modified Polyelectrolytes with Oppositely Charged Mixed Micelles Studied by Fluorescence Quenching

1998

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Pyrene-labeled hydrophobically modified polyanions were prepared by terpolymerization of sodium 2-(acrylamido)-2-methylpropanesulfonate, N-dodecylmethacrylamide (2.5-7.5 mol %), and N-(1-pyrenylmethyl)methacrylamide (1 mol %). Dynamic interactions of these polymers with mixed micelles of n-dodecyl hexa(oxyethylene) glycol monoether (C 12 E 6 ), cetyltrimethylammonium chloride (CTAC), and cetylpyridinium chloride (CPC) (quencher for pyrene fluorescence) were monitored by fluorescence quenching. The charge on the micelle was varied systematically by varying the mole fraction of CTAC (Y) in the mixed micelle. All quenching experiments were performed at Y < Y p , where Y p is a critical Y at which the polymer-micelle systems undergo macroscopic phase separation. A kinetic model was developed to estimate the binding constant (K) (where K ) k 1 /k -1 ), association rate constant (k 1 ), and lifetime of bound micelle on the polymer (residence time) (1/k -1 ) from steady-state and time-dependent fluorescence-quenching data. This analysis led to the following results: K increases with Y because both k 1 and 1/k -1 increase with Y, k 1 being more dependent on Y than 1/k -1 . K markedly increases with increasing concentration of dodecyl groups in the polymers, even at small Y, indicating a strong enhancement of polymer-micelle interactions by hydrophobic interactions. This large increase in the binding constant arises mainly from a large increase in the residence time with increase in the hydrophobe content in the polymers, 1/k -1 being much more dependent on the hydrophobe content than k 1 . The results indicate that complex formation results from hydrophobic interactions between dodecyl groups and the micelle superimposed on the effect of electrostatic force.

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Section: Discussionsupporting

confidence: 61%

Interaction of Pyrene-Labeled Hydrophobically Modified Polyelectrolytes with Oppositely Charged Mixed Micelles Studied by Fluorescence Quenching

1998

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“…But within this series of compounds, the results obtained with various techniques are not consistent. In contrast to the ESR-studies, the rates of fluorescence quenching of pyrene suggest increasing rigidity in the sequence ndodecyl < cyclododecyl < adamantyl (which intuitively may appear the most reasonable) [202], whereas the rate and extent of trans-to cis-isomerization of azo dyes suggest a rigidity scale adamantyl < cyclo-dodecyl < n-dodecyl [203,260]. These apparently contradicting results raise some doubts about the unambiguity of the information obtained by such techniques because they depend on the probe used in a way which cannot be anticipated.…”

Section: Dynamic Propertiescontrasting

confidence: 57%

“…Additionally, the polarity of the sites seems to depend on the rigidity of the hydrophobic tails. In copolymer soaps of "head geometry" based on Polyacrylamide, the polarity around the pyrene probes increases with cyclododecyl < dodecyl < adamantyl tails, which sequence was attributed to the efficiency of steric shielding of the solubilizate [202]. An analogous explanation was given for the decreased polarity around dansyl based probes with increasing degree of hydrophobic substitution of poly(allylamine) [152].…”

Section: Solubilization Of Probe Moleculesmentioning

confidence: 98%

Molecular concepts, self-organisation and properties of polysoaps

Laschewsky

Polysoaps/Stabilizers/Nitrogen-15 NMR

221

126

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The article reviews water-soluble polymers characterized by surfactant side chains, and related amphiphilic polymers. Various synthetic approaches are presented, and rules for useful molecular architectures are given. Models for the self-organization of such polymers in water are presented comparing them with the micellization of low molecular weight surfactants. Highlighting key properties of aqueous polysoap solutions such as viscosity, surface tension and solubilization power, some structure-property relationships are established. Further, the formation of mesophases and of superstructures in bulk is addressed. Finally, the functionalization of polysoaps, and potential applications are discussed.

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“…12 The polyanions PAMPS and PAMPS-Dod were prepared as described earlier. 13,14 PAMPS-Dod is a copolymer of sodium 2-(acrylamido)-2-methylpropanesulfonate (AMPS) and N-n-dodecylmethacrylamide (Dod) with a dodecyl content of 5 mol%. The molecular weight of PAMPS-Dod was determined to be approximately 5×10 4 Dalton by size exclusion chromatography (SEC) on a JASCO GPC-900 system equipped with Shodex Asahipak GF-7 M HQ columns using a 0.2 M solution of LiClO 4 in methanol as the eluent and was calibrated with poly(ethylene glycol) standards (Scientific Polymer Products, Inc.).…”

Section: Methodsmentioning

confidence: 99%

Rheological Properties of Mixtures of Oppositely Charged Polyelectrolytes. A Study of the Interactions between a Cationic Cellulose Ether and a Hydrophobically Modified Poly[sodium 2-(acrylamido)-2-methylpropanesulfonate]

Liu

Morishima

Winnik

2002

Polym J

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ABSTRACT:Mixed solutions of a cationic cellulose ether (JR400) and, either poly[sodium 2-(acrylamido)-2-methylpropanesulfonate] (PAMPS), or a copolymer of sodium 2-(acrylamido)-2-methylpropanesulfonate and N-ndodecylmethacrylamide (PAMPS-Dod) in the semi-dilute regime (10 g L −1 ) have been examined by oscillatory shear and steady shear measurements. Mixtures consisting of the polycation as major component and PAMPS-Dod as minor component, were viscous fluids at low polyanion concentration and became gel-like fluids with increasing polyanion content. The zero shear viscosity was a strong function of polyanion content, increasing significantly with polyanion content. The fluids are viscoelastic, exhibit Newtonian behavior at sufficiently low shear rates and become shear thinning at higher shear rates. Steady shear viscosities were fitted with the Carreau-Yasuda model yielding the time constant associated with the relaxation process. The rheological parameters concurred in support of an association model involving the formation of a crosslinked network between two oppositely charged polyelectrolytes differing greatly in molecular architecture, charge density, and conformation. KEY WORDS Interpolyelectrolyte Complex / Rheology / Sodium 2-Acrylamido-2-methylpropanesulfonate / Transient Network / Polysaccharide / Viscoelasticity / A great variety of consumer products, such as cosmetics, drug formulations, foodstuff or paints rely on the ability of water-soluble polymers to control the rheology of fluids. 1-3 Generally, the polymer is not used alone, but in combination with other polymers or surfactants and it is the synergic action of the components that create the required rheological properties. Of particular interest are systems containing oppositelycharged polymers and surfactants, which form complexes as a result of electrostatic interactions between the charged head group of the surfactant and the ionized units of the polymer, and, in some cases, additional hydrophobic interactions. 4 Mixtures of cationic cellulose ether derivatives and oppositely charged surfactants have been investigated extensively, ever since Goddard reported that the addition of a surfactant, such as sodium dodecylsulfate (SDS), to aqueous cationic cellulose ethers leads to a very large increase in solution viscosity or, in some cases, to phase separation. 5 Further studies have indicated that fluids containing cationic cellulose ethers and anionic surfactants are viscoelastic in given situations and exhibit shear thinning properties that depend in a subtle way on the molecular weight of the polymer and on the nature of the surfactant. 6, 7 The surfactant-triggered changes in viscosity of polyelectrolyte solutions have been attributed either to electrostatic interactions between the charged groups or to hydrophobic interactions between the nonpolar tails of the surfactant and hydrophobic patches along the polysaccharide backbone, or to an interplay of both mechanisms. 8 Another factor that may contribute to the macroscopic rheology of mixe...

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Photoinduced charge separation by chromophores encapsulated in the hydrophobic compartment of amphiphilic polyelectrolytes with various aliphatic hydrocarbons

Cited by 86 publications

References 0 publications

Interaction of Pyrene-Labeled Hydrophobically Modified Polyelectrolytes with Oppositely Charged Mixed Micelles Studied by Fluorescence Quenching

Interaction of Pyrene-Labeled Hydrophobically Modified Polyelectrolytes with Oppositely Charged Mixed Micelles Studied by Fluorescence Quenching

Molecular concepts, self-organisation and properties of polysoaps

Rheological Properties of Mixtures of Oppositely Charged Polyelectrolytes. A Study of the Interactions between a Cationic Cellulose Ether and a Hydrophobically Modified Poly[sodium 2-(acrylamido)-2-methylpropanesulfonate]

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