Self-assembly of a lamellar ABC triblock terpolymer thin film. Effect of substrates

We study the self-assembly in thin films of a lamella-forming polystyrene-block-poly(2-vinylpyridine) -block-poly(tert-butyl methacrylate) triblock terpolymer thin film on a polyimide substrate and compare it with the self-assembly of the same system on a native oxide silicon (SiOx) substrate. In addition to scanning force microscopy, we performed cross-sectional transmission electron microscopy. Both polyimide and SiOx substrates attract the polar P2VP middle block. However, significant differences between the two substrates were revealed: (i) the difference in the interaction strength between the substrate and the polymers caused a different configuration of P2VP chains adsorbed to the substrate and hence a different structure of the first layer, and (ii) the structure of the first layer influenced the self-assembly of the lamellae throughout the entire film. In contrast to SiOx substrates, on polyimide substrates the lamellae with the equilibrium thickness were formed in one step through a new intermediate structure.