Block copolymer thin films

Block copolymer (BCP) represents a special type of polymeric system where each of the polymer chains is composed of two or more chemically distinct homopolymer blocks that are covalently tethered together. Materials made of BCPs are used predominantly in their bulk form, and more recently are finding increasing applications as thin films. The nanoscale feature of patterned BCP thin films makes them ideal for emerging nanotechnologies, including microelectronics, magnetic storage, solar cells, optics and acoustics. Technologies relevant to transfer structure formed by the self-assembly of BCP thin films into patterning applications crucially rely on the precise control of structural orientation, local alignment and long-range ordering. In this article, we review experimental and theoretical progress in tailoring mesoscopic and nanoscopic structures of BCP thin film by using external fields, focusing in particular on the underlying physics of directed self-assembly mechanism. We also review the basic framework of the conventional polymer field-theory and the corresponding numerical solution schemes for the study of BCP thin films, including self-consistent field theory, complex Langevin simulation, dynamical self-consistent field theory, and string methods. Related particle-based simulations are also briefly reviewed. Finally, we provide some experimental and theoretical insights into the next generation of strategies for obtaining desired BCP thin film patterns and their applications in industry.