Thermodynamics of solutions of cyclic polymethylene ester oligomers in p-dioxane and chloroform

✍ Scribed by R. Xu; J. Leonard; V. T. Bui

• Book ID: 101274932
• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 193 KB
• Volume: 38
• Category: Article
• ISSN: 0887-6266
• DOI: 10.1002/(sici)1099-0488(20000201)38:3<443::aid-polb10>3.0.co;2-g

✦ Synopsis

Differential vapor pressures were measured for mixtures of two cyclic polymethylene ester oligomers in p-dioxane and chloroform at 25, 30, 35, and 40 °C at five different concentrations ranging from 1 to 20 wt %. The Flory-Huggins interaction parameter () as well as Leonard's interaction parameter (Ј) for flexible and semiflexible rings were calculated and compared to one another. A new method for the estimation of the number of segments of a cyclic polymer is proposed that allows Leonard's equations to be applied correctly to a particular cyclic compound. Consistent differences between and Ј were observed for all studied mixtures, and the differences became smaller if the cyclic oligomers were considered semiflexible. Interestingly, the enthalpic parameter () deduced from values of and Ј did not differ within their uncertainties. This supports the prediction that mixing cyclic polymer compared to its linear counterpart is mainly due to a molecular configurational entropy difference and that this difference should become less pronounced as the cyclic compound becomes larger.