Morphologies of polymer chains spun onto solid substrates

Abstract

External fields are often present when polymers contact solids, potentially affecting chain adsorption onto a substrate. The adsorbed chains, which are difficult to relax thermally, could semipermanently influence the dynamics of the surrounding chains and bulk chains. In this study, we examined the effect of a force field induced by spin coating on the adsorption of a model polymer chain, DNA. Observations using atomic force microscopy indicated that the morphologies of adsorbed chains were affected not only by the force field but also by the incubation time (tinc) after deposition and before spinning. A longer tinc caused a greater amount of chains to transition from being present in two-dimensional random coil states to stretched states. Conversely, shorter tinc values resulted in many chains being adsorbed in a stretched state. The orientations of the stretched chains reflected the presence of competition between the effects of the centrifugal force and those of the flow rate gradient. At tinc = 0, the adsorbed chains were stretched, and they exhibited many kinks. It was anticipated that this macromolecular information could aid in controlling buried morphologies near solid surfaces and in fabricating promising materials, such as polymer composites and layered organic devices. We investigated the effect of a force field induced by spin coating on the adsorption of a model polymer, DNA. Observations using atomic force microscopy indicated that the morphologies of adsorbed chains were affected not only by the force field but also by the incubation time (tinc) after deposition and before spinning. Shorter tinc values resulted in many chains being adsorbed in a stretched state. The orientations of the stretched chains reflected the presence of competition between the effects of the centrifugal force and those of the flow rate gradient.