Novel nano "island" and "ribbon" morphologies could be fabricatedjust by changing the air-substrate interface of cast films during evaporation. Speeding up or slowing down evaporation of cast films 100-fold allowed diblock molecules containing oligo (phenylene vinylene) dimer as the rod segment and poly (ethylene oxide) as the coil segment to form two different self-assembled nano objects on mica: "islands" and "ribbons," respectively.