Heat capacity of poly (ethylene glycol)-water mixtures: Poly (ethylene glycol)-water interactions
1990; Elsevier BV; Volume: 169; Linguagem: Inglês
10.1016/0040-6031(90)80160-z
ISSN1872-762X
AutoresKingman Ng, Andreas Rosenberg, Margarida Bastos, Ingemar Wadsö,
Tópico(s)Chemical and Physical Properties in Aqueous Solutions
ResumoThe specific heat capacity of the poly(ethylene glycol)-water system has been determined using a drop calorimeter over the full range of composition at 25 °C. The system heat capacity responds linearly to change in composition in the dilute solution regime up to 30% (w/w) and is an irregular function at lower water content. The breakpoint in solubility corresponds to a minimal content of 2.5 water molecules per ethylene oxide to complete hydration. We have difficulty in explaining the large excess heat capacity by the presence of a stoichiometrically defined hydrogen-bonded complex between each ethylene oxide group and water molecules. It seems possible that the water of hydration also interacts with bulk water and/or the rest of the polymer chain.
Referência(s)