Co-solvent and temperature effect on conformation and hydration of polypropylene and polyethylene oxides in aqueous solutions

Dahanayake, Rasika; Dahal, Udaya; Dormidontova, Elena E.

doi:10.1016/j.molliq.2022.119774

Cited by 6 publications

(18 citation statements)

References 51 publications

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“…62 Once this condition is fulfilled, because of a significant shift of ε 1 in the right-hand side of inequality (eq 25), which is often not small (on the order of about 5 k B T for the strength of hydrogen bonds), inequality (eq 25) predicts that it breaks down only when the value of μ is far away from zero, which particularly corresponds to the case of very low concentrations of the cosolvent, such as shown for the collapsed branch of cononsolvency in Figure 10. This prediction concurs with recent atomistic simulations on the cononsolvency of polypropylene oxide 55 in isobutyric acid aqueous solutions, where the concentration of cosolvent isobutyric acid in binary mixed solvents is rather small when polymer collapse starts to occur.…”

supporting

confidence: 91%

“…The latter interaction will be typically weaker as compared to the hydrogen bonding, thus determining the strength of the coupling effect. This concept is supported by a recent atomistic simulation study on the cononsolvency of polypropylene oxide in isobutyric acid aqueous solutions, where cosolvent isobutyric acid can form stable hydrogen bonds with monomers and the isobutyric acid-modified monomers act as hydrophobic nucleation sites for polymer collapse . We note this concept is also supported by a recent experimental study on co-condensation of proteins and DNA, where experiments showed that the protein fused-in-sarcoma adsorbs strongly on ssDNA and tails of adsorbed proteins attract each other (dimerization).…”

Section: Resultssupporting

confidence: 65%

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Cononsolvency Effect: When the Hydrogen Bonding between a Polymer and a Cosolvent Matters

Yong

Sommer

2022

Macromolecules

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Despite the fact that the observation of cononsolvency was reported as early as four decades ago, its phase-transition mechanism is still under debate. In this work, we provided a comprehensive study of the phase behaviors of poly(Nisopropylacrylamide) (PNiPAAm) in sulfoxide or sulfone aqueous solutions. We observed a sharp collapse transition of PNiPAAm brushes in sulfoxide but not in sulfone aqueous solutions by equilibrium measurements of in situ spectroscopic ellipsometry. We found that the hydrogen-bond formation between sulfoxide oxygens and amide hydrogens of the polymer chains plays a critical role in regulating the cononsolvency of PNiPAAm. We have extended the concept of preferential adsorption by taking into account hydrophobic interactions between cosolvent molecules, which are adsorbed on the polymer by hydrogen bonds. This can explain the experimental observations of PNiPAAm brushes in these solvent mixtures and sheds light on understanding the phase behaviors of polymer solutions where hydrogen bonds and hydrophobic interaction play a critical role. Our results can also be of interest for the liquid−liquid phase separation in the living cell where the condensation of proteins bound to large biomacromolecules plays an essential role.

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supporting

confidence: 91%

Section: Resultssupporting

confidence: 65%

Cononsolvency Effect: When the Hydrogen Bonding between a Polymer and a Cosolvent Matters

Yong

Sommer

2022

Macromolecules

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“…Co-solvent localization and potential changes in the micelle structure occurring within the initial 130 ns after introduction of 5% (by volume) alcohols of different hydrophobicities (ethanol, butanol, hexanol) are analyzed together with the dynamics of solvent exchange in the micelle core. In the case of a diblock copolymer, we also investigate the effect of addition of glycine or isobutyric acid, which are capable of stronger hydrogen bonding with polyethers , than simple alcohols. We compare our results with available experimental literature data and make conclusions regarding the micelle sensitivity to the presence of co-solvent for different polymer architectures that provide important insights regarding the interpretation of experimental data and applications of Pluronic micelles in the biomedical area.…”

Section: Introductionmentioning

confidence: 99%

Molecular Structure and Co-solvent Distribution in PPO–PEO and Pluronic Micelles

Dahanayake

Dormidontova

2022

Macromolecules

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The structure and properties of micelles formed by diblock and triblock copolymers containing polypropylene oxide (PPO) and polyethylene oxide (PEO) in aqueous solutions are affected by chain architecture and have important implications for applications, e.g., in the biomedical area. Using atomistic molecular dynamics simulations, we investigate and compare the molecular structure of diblock copolymer PPO 29 PEO 26 , Pluronic L64, and reverse Pluronic 17R4 micelles formed by block copolymers of the same length and composition but different distributions of PPO and PEO blocks in pure aqueous solution or with 5% (by volume) added co-solvents. We show that while the diblock copolymer forms a tightly packed mostly spherical micelle, Pluronic L64 micelles are non-spherical and contain 10−18% (by volume) water in the loosely packed PPO core partially interpenetrated by the PEO block. Reverse Pluronic 17R4 micelles are rather small but relatively well-packed. Addition of 5% (by volume) alcohol to aqueous micelle solutions results in a minimal change in the case of ethanol, while addition of butanol or hexanol leads to an increase of water content in the core and alcohol accumulation at the core−corona interface for the PPO 29 PEO 26 micelle. For L64 micelles, alcohol makes micelles more spherical but enhances defects, e.g., concentrates water in the core center or enhances PEO penetration, depending on the aggregation number. For 17R4 micelles, butanol and especially hexanol penetrate into the micelle core, swelling it. Even stronger core swelling occurs upon addition of 5% (by volume) isobutyric acid to aqueous solution of PPO 29 PEO 26 micelles. We show that the extent of co-solvent penetration and its distribution within the micelles strongly depend on co-solvent hydrophobicity, the capability of hydrogen bond formation with the polymer and micelle architecture, factors that can affect micelle properties and performance in practical applications.

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“…This result is consistent with the PPO block within the NP being hydrated, albeit much less so than the PEO block. 55 Further confirmation of this was achieved by heating these solutions to their critical micelle temperature (CMT) at which point the PPO block would dehydrate. 57 For spectra recorded above CMT, the difference between H2O and D2O emission intensities was small at only 1.2.…”

Section: Cell Imaging With Np1-p188mentioning

confidence: 93%

“…This is plausible as the oxygen atoms within both the PEO and PPO components of P188 are known to form hydrogen bonds with water molecules. 55 This would position 1 in a hydrated microenvironment close to water which would quench emission and broaden absorbance bands. To confirm a role of water in quenching the emission of 1 when confined within NP1-P188 particle, the measurable albeit weak fluorescence spectrum of NP1-P188 was compared in H2O and D2O (Figure 13A).…”

Section: Cell Imaging With Np1-p188mentioning

confidence: 99%

Exploiting Directed Self-Assembly and Disassembly for off-to-on Fluorescence Responsive Live Cell Imaging

Curtin

O’Shea

Garre

et al. 2022

Preprint

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A bio-responsive nanoparticle was formed by the directed self-assembly (DSA) of a hydrophobic NIR-fluorophore with poloxamer P188. Fluorophore emission was switched off when part of the nanoparticle, however upon stimulus induced nanoparticle dis-assembly the emission switched on. The emission quenching was shown to be due to fluorophore hydration and aggregation within the nanoparticle and the turn on response attributable to nanoparticle disassembly with embedding of the fluorophore within lipophilic environments. This was exploited for temporal and spatial live cell imaging with a measurable fluorescence response seen upon intracellular delivery of the fluorophore. The first dynamic response, seen within minutes, was from lipid droplets with other lipophilic regions such as the endoplasmic reticulum, nuclear membranes and secretory vacuoles imageable after hours. The high degree of fluorophore photostability facilitated continuous imaging for extended periods and the off to on switching facilitated the real-time observation of lipid droplet biogenesis as they emerged from the endoplasmic reticulum. With an in-depth understanding of the principles involved, further assembly controlling functional responses could be anticipated.

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Co-solvent and temperature effect on conformation and hydration of polypropylene and polyethylene oxides in aqueous solutions

Cited by 6 publications

References 51 publications

Cononsolvency Effect: When the Hydrogen Bonding between a Polymer and a Cosolvent Matters

Cononsolvency Effect: When the Hydrogen Bonding between a Polymer and a Cosolvent Matters

Molecular Structure and Co-solvent Distribution in PPO–PEO and Pluronic Micelles

Exploiting Directed Self-Assembly and Disassembly for off-to-on Fluorescence Responsive Live Cell Imaging

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