Self-Diffusion Coefficients of Associating Polymers from Pulsed-Gradient Spin-Echo Nuclear Magnetic Resonance Spectroscopy

Macdonald, Peter M.; Uemura, Yoshimitsu; Dyke, Lara; Zhu, Xiaoxia

doi:10.1021/ba-1996-0248.ch020

Cited by 5 publications

(10 citation statements)

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“…Equating the hydrodynamic specific volume indicated by the micellar radius extracted from dynamic light scattering, 4π R H 3 N A /3 pM , with the intrinsic viscosity permits an estimate of the aggregation number as yielding p = 33 ± 9 for ODU and 20 ± 2 for HDU. For C 16 +IPDU (34 kg/mol), a combination of methods, DLS, NMR, and intrinsic viscosity, yielded p = 23 ± 1.…”

Section: Resultsmentioning

confidence: 99%

“…Research to date has established that such polymers in dilute solutions form micelles of radius R (∼20 nm) above a rather low critical micelle concentration ( c cmc ≪ 0.1 wt %) that depends on the backbone molecular weight and the hydrophobe size. − The aggregation numbers are reported from 10 to 80, depending on the molecular structure and method of measurement. With increasing concentration the viscosity rises dramatically, well above that of comparable PEO solutions, providing convincing evidence of a high degree of association.…”

Section: Introductionmentioning

confidence: 99%

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Micellar Solutions of Associative Triblock Copolymers: Entropic Attraction and Gas−Liquid Transition

Pham¹,

Russel²,

Thibeault³

et al. 1999

Macromolecules

137

230

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We report the first clear observations of an entropy-driven phase transition between a dilute micellar “gas” and a disordered but highly associated micellar “liquid” realized with aqueous solutions of poly(ethylene oxide) chains fully end-capped with C16 and C18 hydrophobes. Dynamic light scattering and capillary viscometry determine the radii and aggregation numbers of the micelles and, together with the coexisting concentrations, permit estimates of the strength of the entropic attraction through the adhesive hard-sphere model. The behavior is qualitatively consistent with expectations for the entropy gain from the exchange of end blocks between cores of flowerlike micelles consisting of associative triblock copolymers.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Micellar Solutions of Associative Triblock Copolymers: Entropic Attraction and Gas−Liquid Transition

Pham¹,

Russel²,

Thibeault³

et al. 1999

Macromolecules

137

230

View full text Add to dashboard Cite

show abstract

“…Fluorescence recovery after photobleaching 3,5-9 (FRAP) and forced Rayleigh scattering (FRS) [10][11][12][13] are optical techniques that rely on labeling the chain with a photochromic dye. Steady gradient spin echo (SGSE) and pulsed field gradient nuclear magnetic resonance [14][15][16][17][18][19][20][21] (PFGNMR) use the internal magnetic dipoles of the nuclei as tags in a gradient magnetic field to determine translational motion of single chains. Other labeling and measurement techniques include radioactive tracer, Rutherford backscattering, 22 and even some quasi-elastic neutron scattering experiments.…”

Section: Introductionmentioning

confidence: 99%

Polyelectrolyte Self-Diffusion: Fluorescence Recovery after Photobleaching of Sodium Poly(styrenesulfonate) in N-Methylformamide

Sehgal

Seery

2003

Macromolecules

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The influence of added salt on the self-diffusion coefficients (D self) of fluorescein-tagged sodium poly(styrenesulfonate) (SPS) chains in a high dielectric constant organic solvent was measured by fluorescence recovery after photobleaching (FRAP). N-Methylformamide (NMF) was chosen since it has a dielectric constant greater than that of water and it was hoped would better solvate the backbone. A new FRAP apparatus was built for the purpose that allowed for data collection of the entire modulated recovery profile of fluorescence intensity. The decay rates of the SPS were determined for multiple bleached grating periods and found to be diffusive in nature. D self was measured for a broad range of added salt concentrations (0-0.1 M) for comparison to the diffusive dynamic modes seen by dynamic light scattering. The self-diffusion coefficients were distinct from both the "fast" and the "slow" modes observed in dynamic light scattering and persisted through the ordinary-extraordinary transition. The slight increase in Dself with Cs closely mirrored the "slow" mode diffusion. The slow mode has longer relaxation times as compared to the center-of-mass motion of a single chain, supporting the hypothesis that the slow mode arises from a collective dynamics of large multichain domains.

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“…The class of hydrophobically modified polymers that has received the most scientific attention is telechelics, or linear chains with end-group hydrophobes. Several groups have studied different series of such molecules, where a linear poly(ethylene oxide) (PEO) chain is capped with alkane hydrophobes. − In dilute solution, these molecules self-assemble into flowerlike micelles where, for the majority of chains, both chain ends reside in the same micelle or aggregate. ,, The aggregation number has been reported between 10 and 80 hydrophobes per associated cluster, depending on the measurement technique and the particular molecular architecture. ,,,− Also, the critical aggregation concentration (CAC) is reported to be quite low, though only a few investigations have focused on the most dilute regime where the CAC can be quantified …”

Section: Introductionmentioning

confidence: 99%

“…2,3,12 The aggregation number has been reported between 10 and 80 hydrophobes per associated cluster, depending on the measurement tech-nique and the particular molecular architecture. 3,5,6,[13][14][15][16][17][18] Also, the critical aggregation concentration (CAC) is reported to be quite low, though only a few investigations have focused on the most dilute regime where the CAC can be quantified. 13 As the concentration is increased, chains bridge between micelles, imparting attractions between them and ultimately leading to the formation of an associated network.…”

Section: Introductionmentioning

confidence: 99%

Dynamics in Adsorbed Layers of Associative Polymers in the Limit of Strong Backbone−Surface Attractions

Huang

Santore

2002

Langmuir

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Taken together with the shape of the adsorption isotherm, the adsorption and desorption dynamics of hydrophobically end-modified poly(ethylene oxide) (PEO) on silica suggest that adsorbed layers are comprised of two general populations: a tightly adsorbed underlayer and a loosely bound outer layer. The former is driven by a large number of hydrogen bonding interactions between the PEO's ether groups and nondissociated surface silanols, per the classical model of homopolymer adsorption with tails, loops, and trains. The outer layer is held in place by hydrophobic interactions, about 7-8 kT between the chain ends. In the dilute limit, transport-limited adsorption kinetics suggests that chains adsorb individually and that the adsorbed layer contains only the chains tightly bound via backbone-surface interactions. At greater free solution concentrations, still dilute, entire clusters adsorb and the layer contains both tightly bound and hydrophobically associated populations. The loosely bound outer layer responds to flow: The steadystate adsorbed amount depends on the wall shear rate, decreasing in stronger flows. The loosely bound layer also desorbs at the transport-limited rate in flowing water, facilitating quantification of its binding strength through the application of a hybrid isotherm model combining features of a Langmuir isotherm with those predicted from mean-field treatments of homopolymer adsorption.

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Self-Diffusion Coefficients of Associating Polymers from Pulsed-Gradient Spin-Echo Nuclear Magnetic Resonance Spectroscopy

Cited by 5 publications

References 0 publications

Micellar Solutions of Associative Triblock Copolymers: Entropic Attraction and Gas−Liquid Transition

Micellar Solutions of Associative Triblock Copolymers: Entropic Attraction and Gas−Liquid Transition

Polyelectrolyte Self-Diffusion: Fluorescence Recovery after Photobleaching of Sodium Poly(styrenesulfonate) in N-Methylformamide

Dynamics in Adsorbed Layers of Associative Polymers in the Limit of Strong Backbone−Surface Attractions

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