Molecular orientation and phase separation by controlling chain segment and molecule movement in P3HT/N2200 blends

The molecular orientation and phase separation of poly(3-hexylthiophene) (P3HT) and poly[[N,N-bis(2-octyldodecyl)-napthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5, 5′-(2,2′-bithiophene)] (N2200) blends are investigated by in situ temperature-resolved two-dimensional grazing incidence X-ray diffraction (2D GIXD) in step-by-step heating and cooling processes. When pristine amorphous films are thermally annealed below the melting temperature of P3HT, only the chain segment of P3HT moves, while P3HT molecule is crystallized, induced by N2200 with face-on orientation (thermodynamics unsteady state). The interpenetrating network forms during the crystallization process of the polymers. When thermally annealed above melting temperature of P3HT, the whole molecular chain of P3HT moves, the space restriction of N2200 could be broken. The P3HT crystallizes with edge-on orientation (thermodynamics steady state) while N2200 crystallizes with face-on orientation. The hierarchical morphology forms by nucleation and growth or liquid phase separation. The P3HT crystallization with face-on or edge-on orientation in different postannealing processes is explained in terms of P3HT chain segment and molecule movement confined or broken out by N2200 crystalline confinement.