Reaction Temperature and Solvent Influence Reactivity Ratios in the Copolymerization of Ethylene Oxide and Propylene Oxide
Year: 2025
Type: article
Abstract: High Resolution Image Download MS PowerPoint Slide Statistical copolymers of ethylene oxide (EO) and propylene oxide (PO) are widely used in industry and academia. Despite their decade-long use, the influence of the polymerization conditions on reactivity ratios is underexplored, and surprisingly solution and bulk properties of the resulting polyether copolymers have not been reported in a systematic manner. In this study we examined the copolymerization of EO and PO in a variety of solvents (dimethyl sulfoxide, toluene, anisole) and at different temperatures (25–60 °C), correlating reaction conditions with the thermal and solubility properties of the resulting P(EO- co -PO) copolymers. The copolymerization was monitored online by in situ 1 H NMR spectroscopy to determine the reactivity ratios for the full conversion range. The results show a temperature-dependent trend in reactivity ratios ( r ) for different solvents. In toluene, the reactivity ratios converge with increasing temperature, changing from r PO = 0.26 and r EO = 3.78 at 40 °C to r PO = 0.31 and r EO = 3.21 at 60 °C. A similar pattern is observed in anisole, with the reactivity ratios shifting from r PO = 0.28 and r EO = 3.52 at 40 °C to r PO = 0.30 and r EO = 3.32 at 60 °C, respectively. In contrast, the reactivity ratios in DMSO are generally slightly more similar, with r PO = 0.32 and r EO = 3.10 at 40 °C. Thermal characterization of the polyether copolymers revealed similar melting points of approximately 10 °C and enthalpies of around 40 J·g –1 . Cloud point measurements of the copolymers showed decreased aqueous solubility as the differences in reactivity ratios decreased. These findings demonstrate that the statistical EO/PO copolymerization reaction conditions affect the gradient and thereby significantly influence copolymer physical properties, highlighting the need to consider these parameters for applications.
Source: Macromolecules
Authors: Milena S. Hesse, Gregor M. Linden, Holger Frey
Institution: Johannes Gutenberg University Mainz
Language: English
Subfield: Organic Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,500
OpenAlex ID: W4417285672