Phase separation in miscible blends of polystyrene and poly(vinyl methyl ether): a spin-label study

✍ Scribed by Cameron, G. Gordon; Qureshi, M. Younus; Tavern, Sydney C.

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 177 KB
• Volume: 47
• Category: Article
• ISSN: 0959-8103
• DOI: 10.1002/(sici)1097-0126(199809)47:1<5::aid-pi995>3.0.co;2-a

✦ Synopsis

Polystyrene (PS) samples carrying terminal or in-chain nitroxide spin labels have been blended with poly(vinyl methyl ether) (PVME) in varying proportions and their electron spin resonance (ESR) spectra recorded over a range of temperatures. The spectra are mainly of the slow-motion type but reÑect the plasticizing inÑuence of the PVME on the PS. However, the spectra of the blends containing end-labelled PS (but not those of in-chain-labelled PS) develop a second motionally-narrowed component at a particular temperature which is T f dependent on the proportion of PVME present. As with the cloud point T c

, T f increases with the proportion of PS in the blend, but is about 60¡C below

is the temperature at which the ESR technique is capable T f of detecting the onset of phase separation. Since the spin-label experiment responds to events at a micro or molecular level, is lower than which is T f T c essentially a macroscopic quantity.