Phase Behavior and Hydrogen Bonding in Ternary Polymer Blends of Phenolic Resin/Poly(ethylene oxide)/Poly(ε-caprolactone)

The phase behavior and hydrogen bonding in ternary polymer blends of phenolic resin, poly(ethylene oxide) (PEO), and poly(ε-caprolactone) (PCL) were investigated by using differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). Although all three binary blends are respective miscible, there exists a closed immiscibility loop in the phase diagram due to the so-called “Δχ” and “Δ K ” effects in this hydrogen-bonded ternary polymer system. The interassociation equilibrium constant based on the Painter−Coleman association model between phenolic resin and PEO can be indirectly calculated from the fraction of hydrogen-bonded carbonyl groups. Quantitative analyses show that the hydroxyl−ether interassociation is more favorable than the hydroxyl−carbonyl interassociation at room temperature. The interaction energy density value of B PEO/PCL = −2.85 cal/cm 3 was obtained by comparing the theoretically predicted phase diagram with experimental data.