Miscibility and hydrogen bonding in blends of poly(vinylphenol-co-methyl methacrylate) with poly(ethylene oxide)

Blends of poly(vinylphenol-co-methyl methacrylate) (PVPh-co-PMMA) with poly (ethylene oxide) (PEO) were prepared by solution casting from tetrahydrofur an (THF) solution. The miscibility behavior and hydrogen bonding of blends were investigated by differential scanning calorimetry (DSC), Fourier trans form infrared spectroscopy (FTIR), and solid-state nuclear magnetic resonan ce (NMR). Experimental results indicate that PEO was miscible with PVPh-co- PMMA as shown by the existence of single composition-dependent glass transi tion temperatures over the entire composition range by DSC. In addition, a negative polymer-polymer interaction energy density "B" was calculated base d on the melting depression of PEO using the Nishi-Wang equation. Solid-sta te NMR reveals single-exponential decay of proton spin-lattice relaxation t imes in the rotating frame (T-1p(H)) in the amorphous PVPh-co-PMMA phase. F urthermore, FTIR and solid-state NMR results reveal that at least three com peting equilibria are present in the blend; self-association of PVPh-co-PMM A copolymer (hydroxyl-hydroxyl and hydroxyl-carbonyl) and hydroxyl-ether in terassociation between PVPh and PEG. Quantitative results show that althoug h the hydroxyl-ether interassociation is favored at room temperature, the h ydroxyl-carbonyl self-association dominate's at higher temperatures (> 70 d egreesC). The Painter-Coleman association model (PCAM) can predict three in teracting functional groups based on our experimental results at various te mperatures.