Volumetric properties of aqueous solutions of triblock (PEP) copolymers of ethylene oxide and propylene oxide

✍ Scribed by Lubomír S̆imek; Miloslav BohdaneckÝ

• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 587 KB
• Volume: 32
• Category: Article
• ISSN: 0014-3057
• DOI: 10.1016/0014-3057(95)00110-7

✦ Synopsis

Specific volumes of aqueous solutions of triblock (PEP) copolymers of ethylene oxide and propylene oxide at solute weight fractions 0.1 Q w2 Q 0.39 were measured in the temperature range from 5 to 65°C. Partial molar volumes r2 per chain repeat unit, their temperature quotient 8r2,1aT, and excess partial molar volumes rf were computed. The values of Yr, 8 r22/aT and the absolute values ( P," 1 decrease with increasing content of ethylene oxide units. The excess partial molar expansibility a?!" at infinite dilution for ohgomeric homopolymers (PEO, PPO) were evaluated from reported data. They are positive and display a similar trend to 1 P:I. The values of P: and c?!" are comparable to those reported for lowmolecular-weight cyclic ethers. The results are taken to reflect the effects of polar and apolar groups on the supermolecular structure of water. INTRODUCrION EXPERIMENTAL Volumetric properties are known to provide useful information on the unique types of interactions in aqueous solutions of low-molecular-weight non-electrolytes [l]. The quantities of interest are the partial specific and the partial molar volumes of the solute (4 and r2, respectively), their limiting values at infinite dilution ($, pi), the partial molar expansibility oi2 and its limiting value 07!, and the excess functions, p; and OS:, defined as Polymers. Two hydroxyl-terminated triblock copolymers (PEP) were used. They were provided by the Petrochemical Research Institute, Prievidza, Slovak Republic, and were identical with those used in the previous studies [3-51. Their characteristics are listed in Table .

Solutions in distilled water were prepared by shaking the weighed components overnight at room temperature.