| Polymer blends with anisotropic morphologies were produced by the application of DC or AC electric fields, in the range 0.6–17 kV/cm, to polymer 1/polymer 2/monomer 2 systems during in situ polymerization or polymer 1/polymer 2/solvent and polymer/nanoparticles/solvent systems during solvent evaporation. The dispersed phases were spherical or deformed into ellipsoidal or columnar phases oriented parallel to the field direction or perpendicular to the field direction, depending on the nature of the polymers, the initial concentration of the mixtures and the strength or frequency of the electric fields used. Systems studied included: polystyrene (PS)/poly (cyclohexene oxide) (PCHO)/cyclohexene oxide (CHO), PS/poly (methyl methacrylate) (PMMA)/methyl methacrylate (MMA), PMMA/PS/styrene, poly (ethylene oxide) (PEO)/PS/styrene, poly (tetrahydrofuran) (PTHF)/PS/styrene, PS/PCHO/toluene, PS/6FDA-PFMB (polyimide synthesized from 2,2′-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) and 4,4′-diamino-2,2′-bis(trifluoromethyl)biphenyl (PFMB)]/cyclohexnone, and PS/Al2O3/toluene.; The conductivity measurements of coexisting phases in all the mixtures showed that all the PS-rich phases had lower conductivities. The deformation of the PS-rich inclusion phases was perpendicular to the field direction while the deformation of the PS-poor inclusion phases was parallel to the field direction in accordance with the theory prediction.; The identities of the inclusions phases were changed by a 3.2 kV/cm DC field for a 15% PS/PCHO in situ blend and by 1–100 Hz, 10 kVrms/cm AC fields for a 10% PS/PMMA in situ blend. This was probably due to both viscosity increase in electric fields and also swirling motions in DC and 0.1 Hz AC electric fields that disappear in higher frequency fields. Thus, the in situ polymerization method using applied electric fields makes it possible to attain both equilibrium and non-equilibrium morphologies in polymer blends.; Electric field and pre-dissolved PS had little effect on the molecular weight of the cationically initiated PCHO. The Mw and MWD of free radically initiated PMMA were generally increased by the applied electric field and pre-dissolved PS. Partial phase diagrams were constructed for the PS/PMMA/MMA system. The experimental tie lines in a 10 Hz, 10 kVrms/cm AC field showed a shift of the coexisting curve from the zero-field coexistence curve, that is, an electric field induced mixing effect making the mixture more soluble. |
