title: Near surface properties of mixtures of propylammonium nitrate with n-alkanols 1. Nanostructure.
abstract: In situ amplitude modulated-atomic force microscopy (AM-AFM) has been used to probe the nanostructure of mixtures of propylammonium nitrate (PAN) with n-alkanols near a mica surface. PAN is a protic ionic liquid (IL) which has a bicontinuous sponge-like nanostructure of polar and apolar domains in the bulk, which becomes flatter near a solid surface. Mixtures of PAN with 1-butanol, 1-octanol, and 1-dodecanol at 10-70 vol% n-alkanol have been examined, along with each pure n-alkanol, to reveal the effect of composition and n-alkanol chain length. At low concentrations the butanol simply swells the PAN near-surface nanostructure, but at higher concentrations the nanostructure fragments. Octanol and dodecanol first lower the preferred curvature of the PAN near-surface nanostructure because, unlike n-butanol, their alkyl chains are too long to be accommodated alongside the PAN cations. At higher concentrations, octanol and dodecanol self-assemble into n-alkanol rich aggregates in a PAN rich matrix. The concentration at which aggregation first becomes apparent decreases with n-alkanol chain length.
authors.affiliation: Discipline of Chemistry, The University of Newcastle, Callaghan, NSW 2308, Australia. rob.atkin@newcastle.edu.au.
authors.forename: Aaron
authors.initials: A
authors.lastname: Elbourne
authors.forename: Samuel
authors.initials: S
authors.lastname: Cronshaw
authors.forename: Kislon
authors.initials: K
authors.lastname: Voïtchovsky
authors.forename: Gregory G
authors.initials: GG
authors.lastname: Warr
authors.forename: Rob
authors.initials: R
authors.lastname: Atkin