Anisotropic viscoelasticity and molecular diffusion in nematic wormlike micelles

Wilmsmeyer, Kyle G.; Li, Xiuli; Madsen, Louis A.

doi:10.1080/02678292.2017.1390792

Cited by 5 publications

(6 citation statements)

References 60 publications

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“…Our previous studies have shown the utility of NMR in the measurement of diffusion coefficients and relative populations of unimers and micelles. , The pulsed-field-gradient stimulated echo (PGSTE) sequence was employed to measure diffusion of the various species in solution. , The signal amplitude I was measured as a function of gradient strength ( g ) and was fit with the Stejskal–Tanner equation, where I 0 is the signal amplitude at g = 0, γ is the gyromagnetic ratio, δ is the effective gradient pulse length, Δ is the diffusion time between gradient pulses, and D is the self-diffusion coefficient. Detailed experimental parameters are given in SI section 2.…”

Section: Methodsmentioning

confidence: 99%

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Quantifying Drug Cargo Partitioning in Block Copolymer Micelle Solutions

Uppala

Cooksey

et al. 2020

ACS Appl. Polym. Mater.

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Understanding molecular partitioning in solution is crucial for the design of micelle-based formulations. We investigate PEO−PPO−PEO triblock copolymer micelles and their solubilization of three hydrophobic drugs: hydrochlorothiazide, indomethacin, and paclitaxel. Using NMR diffusometry, we quantify the diffusion coefficients of different species in solution, including polymers, drug cargo molecules, and solvent molecules. Polymer concentration and drug chemistry changes cause effects such as increasing partition percentages of hydrochlorothiazide and indomethacin within micelles as the F127 concentration increases from 1 to 5% w/v. This facile methodology enables quantification of drug distribution in micelles without perturbation of the solution, thus opening opportunities to understand broader processes of cargo partitioning.

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Section: Methodsmentioning

confidence: 99%

“…24,25 The pulsed-field-gradient stimulated echo (PGSTE) sequence was employed to measure diffusion of the various species in solution. 28,29 The signal amplitude I was measured as a function of gradient strength (g) and was fit with the Stejskal−Tanner equation, 30…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Quantifying Drug Cargo Partitioning in Block Copolymer Micelle Solutions

Uppala

Cooksey

et al. 2020

ACS Appl. Polym. Mater.

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“…This NMR technique is nondestructive and enables sensitive determination of diffusion coefficients for various mobile species in solution and in solid materials. Furthermore, NMR diffusometry can track species with molecular and elemental specificity, and thus, it has been used to observe multiple diffusing species in a wide range of polymeric systems. − Relevant to this work, NMR diffusometry experiments can measure unimer and micelle populations for BCP systems. , …”

Section: Introductionmentioning

confidence: 99%

Strong Variation of Micelle–Unimer Coexistence as a Function of Core Chain Mobility

Carrazzone

Foster

et al. 2021

Macromolecules

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Polymeric micelles coexist in solution with unassembled chains (unimers). We have investigated the influence of glass transition temperature (T g ) (i.e., chain mobility) of the micelle core-forming blocks on micelle−unimer coexistence. We synthesized a series of seven PEG-b-P(nBAran-tBA) amphiphilic block copolymers [PEG = poly(ethylene glycol), nBA = n-butyl acrylate, and tBA = tert-butyl acrylate] with similar molecular weights (12 kg/mol). Varying the nBA/tBA molar ratio enabled the broad modulation of core block T g with no significant change in core hydrophobicity or micelle size. NMR diffusometry revealed increasing unimer populations from 0 to 54% of total polymer concentration upon decreasing core block T g from 25 to −46 °C. Additionally, unimer population at fixed polymer composition (and thus core T g ) increased with temperature. This study demonstrates the strong influence of core-forming block mobility on polymer self-assembly, providing information toward designing drug delivery systems and suggesting the need for a new dynamical theory.

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“…[20][21][22] The well-established rheo-NMR methodology usually uses proton detection, for example in protein solution studies, 23,24 and sometimes additional labels like deuterium 25 have been introduced to explore more fundamental soft condensed matter phenomena, for example shear banding in micellear 26 and other systems. 27,28 Rheo-NMR can also be used for sodium detection and it has been shown that multiple quantum filtered (MQF) sodium ( 23 Na) methods can be used to observe the molecular order created in biofluids in shear changing zones under flow. 29 In this work, we applied 23 Na MQF methods in combination with rheo-NMR to monitor the shear-induced molecular order that occurs in the 0.5% k-carrageenan fluid during the temperature ramp as k-carrageenan molecules transition from helices to random coils.…”

Section: Introductionmentioning

confidence: 99%