title: Monolayer study by VSFS: in situ response to compression and shear in a contact.
abstract: Self-assembled octadecyltrichlorosilane ((OTS), CH3(CH2)17SiCl3) layers on hydroxyl-terminated silicon oxide (SiO2) were prepared. The monolayers were characterized with atomic force microscopy (AFM) and contact angle measurements; their conformation was studied before, during, and after contact with a polymer (either PDMS or PTFE) surface using the vibrational sum frequency spectroscopy (VSFS) technique. During contact, the effect of pressure was studied for both polymer surfaces, but in the case of PTFE, the effect of shear rate on the contact was simultaneously studied. The VSFS response of the monolayers with pressure was almost entirely due to changes in the real area of contact with the polymer and therefore the Fresnel factors, whereas sliding caused disorder in the previously all-trans monolayer, as evidenced by a significant increase in the population of gauche defects.
authors.affiliation: KTH Royal Institute of Technology , Division of Surface and Corrosion Science, Drottning Kristinas Väg 51, SE-100 44 Stockholm, Sweden.
authors.forename: Ahmed
authors.initials: A
authors.lastname: Ghalgaoui
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Shimizu
authors.forename: Saman
authors.initials: S
authors.lastname: Hosseinpour
authors.forename: Rubén
authors.initials: R
authors.lastname: Alvarez-Asencio
authors.forename: Clayton
authors.initials: C
authors.lastname: McKee
authors.forename: C Magnus
authors.initials: CM
authors.lastname: Johnson
authors.forename: Mark W
authors.initials: MW
authors.lastname: Rutland