Phase separation in the mixture of schizophyllan and poly(ethylene oxide) in aqueous solution driven by a specific interaction between the glucose side chain and poly(ethylene oxide)

We found that the mixture of schizophyllan and poly(ethylene oxide) in aqueous solution underwent phase separation at around 3-4°C, and this temperature was independent of both polymer concentration and the difference in poly(ethylene oxide) molecular weight (M(w) 6000 and 70,000). The phase- separation took place at the same temperature at which the optical rotation changed. Since the optical rotation change is ascribed to the difference in the nature of hydrogen bonding between the schizophyllan side chain and water, the phase separation is also considered to be due to an interaction between poly(ethylene oxide) and schizophyllan. The phase-separation temperature increased on changing H₂O to D₂O in accordance with a change in the optical rotation, confirming the specific interaction essential for the phase separation. (C) 2000 Elsevier Science Ltd.