Solution thermodynamics of poly(ethylene glycol)/water systems

Abstract

ABSTRACT:The unperturbed molecular dimensions of poly(ethylene glycol) (PEG) samples (of different molecular weights) have been evaluated in aqueous solutions from viscosity measurements at 25, 30, 35, and 40°C. The unperturbed dimension, K , has been determined from extrapolation methods, i.e., Kurata-Stockmayer-Fixman (KSF), Inagaki-Suzuki-Kurata (ISK), and Berry equations. The hydrodynamic expansion factor, ␣ , as well as the unperturbed root-mean-square end-to-end distance, ͗r, found for the system indicated that the polymer coils contract as the temperature is raised from 25 to 40°C. The long-range interaction (excluded volume) parameter, B, was also evaluated and a significant decrease was found for the PEG/water system between 25 and 40°C. The theta temperatures, , were obtained from the temperature dependence of (1/2 Ϫ ) and the second virial coefficient was detected in the temperature interval of 25-40°C for the system and quite a good agreement with the calculated values evaluated via extrapolation and interpolation methods was observed. The thermodynamic interaction parameter was evaluated through the sum of the individual values of enthalpy and entropy dilution parameters, H and S , for PEG samples. All the unperturbed molecular dimensions of PEG/water system were calculated and compared according to M w and M n values of PEG samples. Calculated values were interpreted mainly on the basis of hydrogen-bond formation between polymer segments and PEG-water molecules in solution.

Surface-Bound Proteins with Preserved Functionality

“…30,31 A small Flory-Huggins parameter and close-to-unity intramolecular expansion factor characterize the interactions of PEG with water. 54 The amphipathic composition of this polyether, containing hydrophobic ethylene units (-CH 2 -CH 2 -) and hydrogen-bond-accepting ether oxygens (-O-), appears to dictate its behavior and conformation in aqueous media. Other polyethers, such as polymethylene oxide (i.e., polyformaldehyde) and polypropylene oxide, for example, with higher or lower relative content of ether oxygens, respectively, are not water soluble.…”

Bidirectional Nanoparticle Crossing of Oil–Water Interfaces Induced by Different Stimuli: Insight into Phase Transfer

“…[4,16] MEO 2 MA 90 -co-OEGMA 10 can be simplified as a mixture of PEG and poly(methyl methacrylate) (PMMA) units. [19][20][21] Although Au@MEO 2 MA 90 -co-OEGMA 10 NPs disperse well in water, we still expect c FH,2 % 1 = 2 as the NPs show a noticeable surface activity in water (see Figure S2 in the Supporting Information). [19][20][21] In contrast, water is a good solvent for PEG units (c FH,2 (PEG) % 1 = 2 ) but poor for PMMA units (c FH,2 (PMMA) > 1 = 2 ).…”

“…[2] E p can be evaluated from E p = n 1 f 1 (c FH,1 ) + n 2 f 2 (c FH,2 ), where n i are the number of polymer chains, and f i is the free-energy associated with the Flory-Huggins parameters (c FH,i ) of the polymer shells in each medium. [19][20][21] In contrast, water is a good solvent for PEG units (c FH,2 (PEG) % 1 = 2 ) but poor for PMMA units (c FH,2 (PMMA) > 1 = 2 ). Toluene is a good solvent for both PEG and PMMA units (c FH,1 (PEG) < 1 = 2 and c FH,1 (PMMA) < 1 = 2 ), namely, c FH,1 < 1 = 2 .…”

“…Toluene is a good solvent for both PEG and PMMA units (c FH,1 (PEG) < 1 = 2 and c FH,1 (PMMA) < 1 = 2 ), namely, c FH,1 < 1 = 2 . [19][20][21] In contrast, water is a good solvent for PEG units (c FH,2 (PEG) % 1 = 2 ) but poor for PMMA units (c FH,2 (PMMA) > 1 = 2 ). [19][20][21] Although Au@MEO 2 MA 90 -co-OEGMA 10 NPs disperse well in water, we still expect c FH,2 % 1 = 2 as the NPs show a noticeable surface activity in water (see Figure S2 in the Supporting Information).…”

Structural and morphological characterization of Poly(o-ethoxyaniline) Emeraldine-salt form using FTIR, XRD, LeBail Method and SEM

“…Recent studies have shown that for PANI-ES, the percentage of crystallinity obtained was 22% [29] by the ratio of the area of the peaks and the amorphous halo method. Bhadra et al [30] obtained PANI-ES chemically synthesized with percentage of 60.8%.…”