Abstract: The electron spin resonance(ESR) spectra of PEO end labeled with nitroxide groups were recorded over a temperature range for the bulk polymer and for(1;3 by mass ratio) blends with styrene-vinylphenol copolymer(STVPh) containing different hydroxyl groups. For SLPEO, ESR spectra are composed of a single component, indicating the spin label locating in a single environment. For SP-1, SP-9 and SP-26 blends, two spectral components with different rates of motiona "fast" component and a "slow" component are observed in the experimental temperature range. It can be concluded that the fast and slow components should be attributed to micro heterogeneitYIN the blends: nitroxide radical trapped in the PEO rich and STVPh rich regimes in the blends, respectively. The miscibility of the blends increases with increasing hydrogen bonding density due to the specific interaction between hydroxyl groups in STVPh and the ether oxygen in PEO. Accordingly, the T_5mT, E_a, τ_c values are increased owing to the decrease of the SLPEO mobility of chain motion with increasing hindrance of physical cross-linking density.

Key words: ESR, Spin label, Polymer blend, Miscibility, Hydrogen bonding