Monte Carlo simulations of copolymer adsorption at planar chemically patterned surfaces: Effect of surface domain sizes

We present results of Monte Carlo simulation studies utilizing the bond fluctuation model in conjunction with single and configurational biased Monte Carlo moves to investigate the adsorption of diblock ~A–b–B! and alternating ~A–alt–B! copolymers at physically flat surfaces made of an equal number of two chemically different sites, C and D. The adsorption of the copolymer to the surface is driven by the repulsion between the A and B segments along the copolymer and the attraction between the B segments and the D sites on the surface. We address the critical role of the commensurability between the copolymer’s monomer sequence distribution and the size and spatial distribution of the surface adsorbing sites on the copolymer adsorption. We show that both copolymer architectures have the ability to recognize the surface motif and transcribe it into the bulk material. Diblock copolymers can transfer the pattern once the heterogeneous domain sizes match the size of the parallel component to the radius of gyration, which is constituted primarily of the adsorbing species. This behavior results from the ability of the diblock copolymer to adopt a brush type conformation. In contrast to the diblocks, copolymers with the alternating sequence distribution are more likely to ‘‘zip to’’ the surface since the adsorbing species are evenly distributed along the copolymer. This chain conformation creates an entropic penalty, which must be alleviated by the formation of loops and tails. These conformational changes endow the alternating copolymer with the ability to recognize patterns with periodicities much less than the parallel component to the radius of gyration, and to invert the pattern as the distance away from the surface is increased. © 2003 American Institute of Physics. @DOI: 10.1063/1.1597872#