Effect of temperature on poly(ethylene oxide) chains in aqueous solution. A viscometric, 1H NMR and Raman spectroscopic study

Hey, Michael J.; Ilett, Stephen M.; Davidson, G.

doi:10.1039/ft9959103897

Cited by 64 publications

(45 citation statements)

References 16 publications

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“…Other values of τ c are given in Table . When the reorientational correlation time ( τ c ) of the internuclear vector is smaller than the reciprocal of the proton resonance frequency in the extreme narrowing limit, the NMR T 1 relaxation time is given by

\frac{1}{T_{1}} = \frac{3}{2} {(\frac{μ_{0}}{4 π})}^{2} \frac{γ^{4} ћ^{2} τ_{c}}{r^{6}},

where μ 0 is the permeability of free space, γ is the magnetogyric ratio of the proton, and r is the interproton distance . It has been observed from Figure c that the correlation time of the EO unit of the PEG‐based polymers decreases with the increase in the temperature of the medium, suggesting a free motion of the polymer.…”

Section: Resultsmentioning

confidence: 97%

Structural and dynamical aspects of PEG/LiClO₄ in solvent mixtures via NMR spectroscopy

Singh

Nanda

Dorai

2019

Magnetic Reson in Chemistry

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Motivated by the potential usefulness of polyethylene glycol (PEG)/Li+ salt mixtures in several industrial applications, we investigated the structure and dynamics of PEG/LiClO4 mixtures in D2O and its mixtures with CD3CN and DMSO‐d6, in a series of PEG‐based polymers with a wide variation in their molecular weights. 1H NMR chemical shifts, T1/T2 relaxation rates, pulsed‐field gradient NMR diffusion experiments, and 2D HOESY NMR studies have been performed to understand the structural and dynamical aspects of these mixtures. Increasing the temperature of the medium results in a significant perturbation in the H‐bonded structure of PEG in its PEG/LiClO4/D2O mixtures as observed from the increase in chemical shifts. On the other hand, the addition of molecular cosolvents has a negligible effect. The hydrodynamic structure of PEG shows a pronounced variation at low temperature with increasing molecular weight, which, however, disappears at higher temperatures. Increasing the temperature leads to a decrease in the hydrodynamic structure of PEG, which can be explained on the basis of solvation–desolvation phenomena. The 2D HOESY NMR spectra reveal a new finding of Li+‐water binding in the PEG/LiClO4/D2O mixtures with the addition of molecular solvents, suggesting that the Li+ cation diffuses freely in the D2O mixtures of polymers as compared with the polymer mixtures with DMSO or CD3CN.

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\frac{1}{T_{1}} = \frac{3}{2} {(\frac{μ_{0}}{4 π})}^{2} \frac{γ^{4} ћ^{2} τ_{c}}{r^{6}},

Section: Resultsmentioning

confidence: 97%

Structural and dynamical aspects of PEG/LiClO₄ in solvent mixtures via NMR spectroscopy

Singh

Nanda

Dorai

2019

Magnetic Reson in Chemistry

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“…14 Irradiation led to localized heating, which presumably increased the fluidity of the PEG/HPPH layer, enabling HPPH to rapidly diffuse to the interface and interact with BSA. We speculate that this change might be the result of disruption of the hydration of the PEG 51 and/or partial collapse of the PEG layer, 52 increasing molecular motion due to thermal energy. A linear burst release (69.2 ± 5.0 %) in the first 45 min was observed, after which the release proceeded gradually, only reaching ~75 % when the study terminated after two hours.…”

Section: Resultsmentioning

confidence: 99%

Understanding the interactions between porphyrin-containing photosensitizers and polymer-coated nanoparticles in model biological environments

Jenkins

Srivatsan

Reynolds

et al. 2016

Journal of Colloid and Interface Science

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Non-covalent incorporation of hydrophobic drugs into polymeric systems is a commonly-used strategy for drug delivery because non-covalent interactions minimize modification of the drug molecules whose efficacy is retained upon release. The behaviors of the drug-polymer delivery system in the biological environments it encounters will affect the efficacy of treatment. In this report, we have investigated the interaction between a hydrophobic drug and its encapsulating polymer in model biological environment using a photosensitizer encapsulated in a polymer-coated nanoparticle system. The photosensitizer, 3-(1′-hexyloxyethyl)-3-devinylpyropheophorbide-a (HPPH), was non-covalently incorporated to the poly(ethylene glycol) (PEG) layer coated on Au nanocages (AuNCs) to yield AuNC-HPPH complexes. The non-covalent binding was characterized by Scatchard analysis, fluorescence lifetime, and Raman experiments. The dissociation constant (Kd) between PEG and HPPH was found to be ~35 μM with a maximum loading of ~2.5 × 105 HPPHs/AuNC. The release was studied in serum mimetic environment and in vesicles that model human cell membranes. The rate of protein-mediated drug release decreased when using a negatively-charged or cross-linked terminus of the surface-modified PEG. Furthermore, the photothermal effect of AuNCs can initiate burst release, and thus allow control of the release kinetics, demonstrating on-demand drug release. This study provides insights regarding the actions and release kinetics of non-covalent drug delivery systems in biological environments.

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“…In general, anionic hydrotropic surfactants are believed to increase the cloud [16]. As a consequence, electrostatic repulsion created by the addition of charged species prevents aggregation of these micelles and thus leads to an increase in the cloud point [34][35][36][37][38]. In the case of mono-versus disulfonate surfactants, differences in molecular shape and a slight kink in the alkyl tail structure will also affect their packing parameter and thus the size of the resulting micelles [39].…”

Section: Effect Of Alkyl Tail Length On Hydrotropic Efficiency Of Paementioning

confidence: 99%

Performance of New Biodegradable Di‐Sulfonate Surfactants as Hydrotropes in High‐Temperature and Salinity Environments

Behr

Tucker

Daugs

2014

J Surfact & Detergents

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Propyl alkyl ether sulfonate (PAES) surfactants, recently developed by The Dow Chemical Company, show excellent electrolyte, hard water and caustic solubility, with attractive ECOTOX profile and biodegradability. Due to their unique structure and properties, they are good candidates for use as hydrotropes in formulations containing nonionic surfactants. The goal of these studies was to evaluate hydrotropic efficiency of PAES materials via cloud point analysis. The effects of PAES alkyl tail length, concentration, and mono-and di-sulfonate components on the cloud point of TERGITOL TM 15-S-9 in solutions of varying electrolyte strength were investigated. In the presence of high electrolyte levels, PAES 12C had the highest hydrotropic efficiency of all materials tested, including commonly used commercial hydrotropes. Disulfonate components of the PAES materials were found to be more efficient hydrotropes than mono-sulfonate in high electrolyte environments for all tail lengths tested. The di/ mono ratio and tail length were found to be critical parameters.

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Effect of temperature on poly(ethylene oxide) chains in aqueous solution. A viscometric, 1H NMR and Raman spectroscopic study

Cited by 64 publications

References 16 publications

Structural and dynamical aspects of PEG/LiClO₄ in solvent mixtures via NMR spectroscopy

Structural and dynamical aspects of PEG/LiClO₄ in solvent mixtures via NMR spectroscopy

Understanding the interactions between porphyrin-containing photosensitizers and polymer-coated nanoparticles in model biological environments

Performance of New Biodegradable Di‐Sulfonate Surfactants as Hydrotropes in High‐Temperature and Salinity Environments

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Effect of temperature on poly(ethylene oxide) chains in aqueous solution. A viscometric, 1H NMR and Raman spectroscopic study

Cited by 64 publications

References 16 publications

Structural and dynamical aspects of PEG/LiClO4 in solvent mixtures via NMR spectroscopy

Structural and dynamical aspects of PEG/LiClO4 in solvent mixtures via NMR spectroscopy

Understanding the interactions between porphyrin-containing photosensitizers and polymer-coated nanoparticles in model biological environments

Performance of New Biodegradable Di‐Sulfonate Surfactants as Hydrotropes in High‐Temperature and Salinity Environments

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Structural and dynamical aspects of PEG/LiClO₄ in solvent mixtures via NMR spectroscopy

Structural and dynamical aspects of PEG/LiClO₄ in solvent mixtures via NMR spectroscopy