Reduction of the interfacial tension between 'immiscible' polymers: to which phase one should add a compatibilizer

The reduction of interfacial tension a between polyethylene oxide (PEO) and polypropylene oxide (PPO) by either a triblock copolymer EO-PO-EO or a dib lock copolymer styrene-EO was studied by means of the pendant drop method f rom 70 to 120 degreesC. Time independent data correspond to stationary stat es and do not represent equilibrium information. The addition of the compat ibilizer to the PPO phase is approximately twice as efficient as the additi on to the PEO phase for both block copolymers. Knowing the concentration de pendence of sigma for one of the coexisting phases it is possible to foreca st the effects resulting from the addition of the other phase by means of m odel considerations based on the partition coefficient of the additive and the ratio of the viscosities of the coexisting phases. (C) 2001 Elsevier Sc ience Ltd. All rights reserved.