AN XPS STUDY OF THE SURFACE REORIENTATION OF STATISTICAL METHACRYLATE COPOLYMERS

The surface of two statistical copolymers, poly(2-hydroxyethyl methacrylate-co-butyl methacrylate) (HEMA-co-BMA) and poly(2-[2-(2-ethoxy)ethoxy] ethyl methacrylate-co-butyl methacrylate) (EOEOEMA-co-BMA), was investigated by two techniques of X-ray photoelectron spectroscopy (XPS)-the classical ''dry'' technique and the ''deep-freezing'' in hydrated state technique. The observed differences are discussed from the point of view of the polymer surface chain reorientation in response to the environment changes. Taking the XPS spectra at various take-off angles (TOA), the carbon and oxygen concentration profiles on dry and hydrated sample surfaces were obtained. The depth in which reorientation of polymer chains occurs was determined (similar to 4.5 mn) and surface contamination during the ''deep freezing'' method was considered. Regressive polymer chain reorientation from the hydrated toward the dry state was also followed. (C) 1995 Academic Press, Inc.