Phase Behavior in Blends of Ethylene Oxide-Propylene Oxide Copolymer and Poly(ether sulfone) Studied by Modulated-Temperature DSC and NMR Relaxometry

• Published in: Chemistry : a European journal Vol. 15; no. 5; pp. 1177 - 1185
• Main Authors: Van Lokeren, Luk, Gotzen, Nicolaas-Alexander, Pieters, Ronny, Van Assche, Guy, Biesemans, Monique, Willem, Rudolph, Van Mele, Bruno
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 19.01.2009; WILEY‐VCH Verlag
• Subjects: differential scanning calorimetry; NMR relaxometry; phase diagrams; polymer blends; polymers
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.200801555

The state diagram of a blend consisting of a copolymer containing ethylene oxide and propylene oxide, P(EO‐ran‐PO), and poly(ether sulfone), PES, is constructed by using modulated‐temperature differential scanning calorimetry (MTDSC), T2 NMR relaxometry, and light scattering. The apparent heat capacity signal in MTDSC is used for the characterization of polymer miscibility and morphology development. T2 NMR relaxometry is used to detect the onset of phase separation, which is in good agreement with the onset of phase separation in the apparent heat capacity from MTDSC and the cloud‐point temperature as determined from light scattering. The coexistence curve can be constructed from T2 values at various temperatures by using a few blends with well‐chosen compositions. These T2 values also allow the detection of the boundary between the demixing zones with and without interference of partial vitrification and are in good agreement with stepwise quasi‐isothermal MTDSC heat capacity measurements. Important interphases are detected in the heterogeneous P(EO‐ran‐PO)/PES blends. And relax! A new and elegant method for studying the phase behavior of liquid (polymer) blend systems by using T2 NMR relaxometry is reported (see figure for the coexistence curve of P(EO‐ran‐PO)/PES as constructed by a stepwise isothermal T2 NMR relaxometry experiment (×), starting from four blends with well‐chosen compositions).