Evolution of Microstructure in Block Copolymer Thin Films during Zone Annealing

Abstract

The effect of zone annealing on a microstructure from horizontal and vertical cylinders in the microphase-separated films of polystyrene–polybutadiene–polystyrene triblock copolymer and polystyrene–poly(4-vinylpyridine) diblock copolymer is studied. It is shown that processing of the films of different thicknesses at various maximum thermal front temperatures which do not exceed the temperature of orderdisorder transition does not lead to a noticeable increase in their degree of ordering. On the contrary, once the transition temperature is approached, the interfacial area between domains formed by different types of blocks is increased and the order in their arrangement disappears, with the thermal stability of the structure falling with an increase in film thickness. Thus, the substantial microstructure ordering during the cold zone annealing of the polystyrene–poly(methyl methacrylate) diblock copolymer described in the literature has not yet been reproduced for other systems. The maximum rate of gradient zone motion at which this effect is to be expected is estimated.