Conformational aspects of model chromatographic surfaces studied by sum-frequency generation Original Research Article

Several model chromatographic surfaces composed of mixed octadecyl (C18-) and methyl (C1-) modified fused silica surfaces were examined by sum-frequency generation (SFG) spectroscopy, X-ray photoelectron spectroscopy (XPS), contact angle measurements and atomic force microscopy (AFM). Results indicate that the modified surface displaying the highest relative percentage of gauche defects in the bound C18 chains, as manifested in the sum-frequency data, also shows the highest work of adhesion as determined by contact angle measurements, demonstrating the link between the molecular configuration and the macroscopic energy of the surface. The surfaces were also examined with atomic force microscopy (AFM) to investigate multilayer formation. The results are discussed in terms of the effect of this observation on reverse-phase chromatographic applications.