The Characterization of a Polyethylene Oxide-b-Polystyrene Block Copolymer

Indianapolis, IN

Block copolymers consist of two distinct monometric polymers arranged in covalently linked chains. If the monomer groups have sufficiently different physical properties, such as one being relatively polar while the other is relatively nonpolar, when cast on a suitable substrate as a thin film the two portions of the chain can phase separate creating remarkable structures within the film. In this research, a polyethylene oxide-b-polystyrene block copolymer was studied to observe phase separated structures. A block copolymer solution was created by dissolving the polymer in toluene. Thin films were created by either drop casting with a pipette or using a spin coater to transfer the toluene solution onto a polished silicon or glass substrate. The films were characterized using atomic force microscopy (AFM), Raman, and infrared spectroscopies. AFM imaging has shown interesting surface texture and morphology, but distinct phase separated features have yet to be observed. Spectroscopic results, however, support the presence of two distinct phases at the surface. Changes to the polymer solution composition and casting procedures/conditions are being tested in order to successfully create and image phase separated structures using AFM.