Investigation of phase behavior and water binding in poly(alkylene oxide) solutions

Abstract

SynopsisThe aqueous solution properties of alkylene oxide polymers and copolymers are related t o their interaction with water. In an attempt to better understand this behavior, differential scanning calorimetry has been employed to measure phase changes and water binding in solutions of polyethylene glycol (PEG), polypropylene glycol (PPG), and a 50/50 random copolymer of ethylene oxide and propylene oxide. PEG (mn = 3510) forms a crystalline eutectic with water at 0.48 weight fraction of polymer. The liquidus curve for water can be fit accurately using the Flory-Huggins expression for solute activity with an interaction parameter of 0.05. PPG and the random copolymer do not crystallize and thus do not form a crystalline eutectic. Based on decreases in the heat of fusion of free water with added polymer, PEG binds more water than the copolymer which binds more water than PPG. The estimated hydration numbers per polymer segment are 1.5 for PPG, 2.3 for the copolymer, and 2.7 for PEG.

The Lyotropic Cubic Phase of Model Associative Polymers: Small-Angle X-Ray Scattering (SAXS), Differential Scanning Calorimetry (DSC), and Turbidity Measurements

“…as described above. The fact that the solution is gel-like, i.e., has a yield stress value, indicates that the origin of the In the figure is also indicated the theoretical crystallinity of the unmodified analogue (53), showing no crystallinity be-endothermic peak is the melting of a mesomorphic phase; the X-ray measurements below in fact show that it is a cubic low 50 wt%. For the case when no water is present the crystallinity is lower for the modified form and this might phase.…”

Experimental techniques for characterising water in wood covering the range from dry to fully water-saturated

“…Besides the above-described method for determining FSP, an additional one has been reported in several studies (Simpson and Barton 1991;Zauer et al 2014;Zelinka et al 2012) in which samples within a wide range of MC have been used and a linear regression is constructed between MC and specific enthalpy measured. The inflection point of this linear regression is then FSP, and the slope of the line is the enthalpy of water associated with the wood structure (Hager and Macrury 1980). In some studies (Simpson and Barton 1991;Zauer et al 2014;Zelinka et al 2012), it is stated that this method is more correct as it does not assume any specific value of the melting enthalpy.…”

A study of the hydration of polyoxyethylene at low temperatures by differential scanning calorimetry

“…The hydration of polyoxyethylene or nonionic surfactants containing a polyoxyethylene chain has been studied by many authors [3][4][5][6][7][8][9][10][11][12][13][14][15]. Generally, the results show that the basic hydration of polyoxyethylene is reached at about 50 % W/W water.…”

“…Generally, the results show that the basic hydration of polyoxyethylene is reached at about 50 % W/W water. Based on these experimental observations most authors conclude that 2 or 3 water molecules are needed for complete hydration of one oxyethylene unit [3,[6][7][8]15]. Some authors emphasize that the hydration is temperature dependent [9][10][11].…”