Abstract
Water potential (Ψω) values were determined for aqueous colloids of four molecular sizes of polyethylene glycol (PEG) using freezing-point depression and vapor-pressure deficit methods. A significant third-order interaction exists between the method used to determine Ψω, PEG molecular size, and concentration. At low PEG concentrations, freezing-point depression measurements result in higher (less negative) values for Ψω than do vapor-pressure deficit measurements. The reverse is true at high concentrations. PEG in water does not behave according to van't Hoff's law. Ψω is related to molality for a given PEG but not linearly. Moreover, Ψω varies with the molecular size of the PEG. It is suggested that the Ψω of PEG in water may be controlled primarily by the matric forces of ethylene oxide subunits of the PEG polymer. The term matricum is proposed for PEG in soil-plant-water relation studies.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Jackson W. T. Use of Carbowaxes (Polyethylene Glycols) as Osmotic Agents. Plant Physiol. 1962 Jul;37(4):513–519. doi: 10.1104/pp.37.4.513. [DOI] [PMC free article] [PubMed] [Google Scholar]
- LAGERWERFF J. V., OGATA G., EAGLE H. E. Control of osmotic pressure of culture solutions with polyethylene glycol. Science. 1961 May 12;133(3463):1486–1487. doi: 10.1126/science.133.3463.1486. [DOI] [PubMed] [Google Scholar]
- Richards L. A., Ogata G. Thermocouple for Vapor Pressure Measurement in Biological and Soil Systems at High Humidity. Science. 1958 Oct 31;128(3331):1089–1090. doi: 10.1126/science.128.3331.1089. [DOI] [PubMed] [Google Scholar]