Preparation of polymer latex particles with immobilized sugar residues and their surface characterization by x-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) and X-ray photoelectron spectroscopy (XPS) have been employed for the surface chemical analysis of a series of polymer colloids with immobilized sugar residues. A thioglycoside, based on galactose (GAL), with an acryloyl group in the aglycon side chain has been prepared, characterized, and copolymerized with styrene in various proportions by surfactant-free emulsion polymerization employing potassium persulfate initiator. The quantitative elemental and chemical state XPS information suggests the presence of the steric stabilizing water-soluble polymer layer at the colloid surface. These data are complemented by the detection of signals in the ToF-SIMS spectra which are specifically characteristic of the sugar derivative, including those attributable to the intact GAL molecule. The changes within the C 1s core level spectra from the XPS analysis and also the area ratios of diagnostic signals in the ToF-SIMS spectra reflected the increase in the surface level of GAL with increasing bulk levels of the galactose derivative. These changes correlate very well with the observed substantial decrease in particle size and electrophoretic mobility of the poly (styrene) (PS)-based colloids as function of the level of GAL employed, reflecting the presence of a steric stabilizing water-soluble polymer layer at the colloid surface. The data are discussed briefly in terms of the mechanism of colloid formation to provide an explanation of GAL surface enrichment but primarily concentrate on the role of ToF-SIMS and XPS for the surface analysis of these complex polymer colloids.