Ordered Diblock Copolymer Films on Random Copolymer Brushes

Abstract

Optical microscopy, neutron reflectivity, and small angle neutron scattering studies were used to investigate the structure of thin films of symmetric diblock copolymers of P(dS-b-MMA) as the interactions between the copolymer and the substrate were changed in a systematic manner. In cases where there was a strong preferential segregation of one of the components to the substrate, the lamellar microdomains were oriented parallel to the film surface. However, on a nearly neutral substrate, a mixed morphology was found where the lamellae adjacent to the free surface are oriented parallel to the plane of the film, while the lamellae adjacent to the substrate are oriented normal to the plane of the film.

Selective Doping of Block Copolymer Nanodomains by Sputter Deposition of Iron

“…Because the substrates are neutral, the cylindrical domains in P(S-b-MMA) block copolymer thin films orient predominantly perpendicular to the substrate surface. [50][51][52][53][54] Although the substrate is neutral to both blocks of the used P(S-b-MMA) copolymer, not all PMMA Figure 1. Schematic side view of the basic setup used in the in situ GISAXS experiment during sputter deposition.…”

Surface Energies and Self-Assembly of Block Copolymers on Grafted Surfaces

“…Such approaches were pioneered by Mansky et al, who showed that the surface energies of polystyrene (PS) and polymethylmethacrylate (PMMA) homopolymers can be tuned by the use of a grafted layer of random copolymer P(S-r-MMA) with different chemical compositions of the monomers in the grafted chains. In this manner, they demonstrated that the grafted layers can furnish a neutral surface which is effective in creating perpendicularly aligned phases [6,7]. Subsequent work has advanced this idea to other systems by using alternative strategies such as crosslinking agents and/or grafting chemistries [2].…”

“…Indeed, grafted layers are soft substrates which can potentially modulate their thicknesses and/or allow for interpenetration to accommodate the morphology of selfassembly. Moreover, there is an underlying assumption that the surface energies of A and B homopolymers, usually determined through contact angle measurements, suffice to characterize the influence of interfacial interactions upon the self-assembly of the AB block copolymer [6][7][8]. However, such an assumption ignores the fact that the conformations and the energetics of block copolymers near grafted surfaces will depend explicitly on the self-assembled morphologies themselves, and can in general be different from the characteristics of the homopolymers.…”

Field-theoretic simulations of block copolymers : design and solvent annealing.

“…This behavior has led to numerous experimental and theoretical studies of cylinder-forming copolymer thin films to try and develop a general strategy for annealing C ⊥ . Towards this end, Hawker and Russell et al made a significant contribution by introducing random copolymer brushes grafted to wafer substrates, creating a neutral mean-field environment for the copolymer blocks [19]. In fact, the majority of successful experiments resulting in perpendicular cylinders, with the exception of ultra-thin films, use this method.…”