On the origin of the extremely different solubilities of polyethers in water

Abstract

The solubilities of polyethers are surprisingly counter-intuitive. The best-known example is the difference between polyethylene glycol ([–CH 2 –CH 2 –O–] n ) which is infinitely soluble, and polyoxymethylene ([–CH 2 –O–] n ) which is completely insoluble in water, exactly the opposite of what one expects from the C/O ratios of these molecules. Similar anomalies exist for oligomeric and cyclic polyethers. To solve this apparent mystery, we use femtosecond vibrational and GHz dielectric spectroscopy with complementary ab initio calculations and molecular dynamics simulations. We find that the dynamics of water molecules solvating polyethers is fundamentally different depending on their C/O composition. The ab initio calculations and simulations show that this is not because of steric effects (as is commonly believed), but because the partial charge on the O atoms depends on the number of C atoms by which they are separated. Our results thus show that inductive effects can have a major impact on aqueous solubilities.

Roles of Proton in the Formation of Particles: Soap‐free Emulsion Polymerization of Styrene using AIBN and Potassium Persulfate as Initiators

“…Moreover, this proposition provides a qualitative answer to the problem annoying researchers for decades, [50] namely the extreme difference of polyethylene glycol (PEG) and polyformaldehyde (POM) in the water solubility. POM is extremely insoluble, whereas PEG is miscible with water at any ratio.…”

“…[45,47,48] Taking into account the high concentration of protons at the interface of water/air, [49] the affinity of hydrophobic chain for protons shows a strong relation with the decrease of surface tension. Moreover, this proposition provides a qualitative answer to the problem annoying researchers for decades, [50] namely the extreme difference of polyethylene glycol (PEG) and polyformaldehyde (POM) in the water solubility. POM is extremely insoluble, whereas PEG is miscible with water at any ratio.…”

New Wine in Old Bottles: Prolonging Room‐Temperature Phosphorescence of Crown Ethers by Supramolecular Interactions

“…Therefore, attention was focused on their intra‐ or intermolecular interactions considering their numerous oxygen atoms. Their ring‐shaped structure endowed intertwined intramolecular C⋅⋅⋅O interactions which might be the driving force for conformation rigidification (Figure a and b) . It should be noted that the longer the glycol chain, the more are the C⋅⋅⋅O interactions.…”

Hydration interactions beyond the first solvation shell in aqueous phenolate solution

“…DFT-MD simulations have been shown to accurately model the aqueous solvation of small solutes [69][70][71] and to predict the anisotropy decay of water in such solutions reasonably well. 36 Fig. 5 shows the OH-anisotropy decays of water molecules in phenol and phenolate solutions and in neat water, as obtained from our simulations.…”

“…[11][12][13][14][15][16][17][18][19][20][21][22][23] Time-resolved vibrational spectroscopy is very well suited for investigating aqueous solvation, because the hydrogen bonds between a solute and the OH groups of solvating water molecules can be probed in a direct manner by tracking the dynamics (frequency fluctuations and orientational diffusion) of the OH-stretch (or OD-stretch) mode. [24][25][26][27][28][29][30][31][32][33][34][35][36][37] Up to now, timeresolved OH-stretch (and OD-stretch) spectroscopy studies of anion solvation have focused mostly on single-atom anions, notably the halides. 24,26,27,31,38 These experiments have shown that the local restructuring of the hydrogen-bond network by the anions leads to a slowing down of the dynamics of the water molecules in the first solvation shell: for some anions, the correlation time of the random orientational motion of the OH bonds involved in the water-anion hydrogen bonds is more than an order of magnitude slower than in bulk water.…”