title: Blends of amphiphilic trisilanolisobutyl-POSS and phosphine oxide substituted poly(dimethylsiloxane) at the air/water interface.
abstract: Mixtures of a polyhedral oligomeric silsesquioxane, trisilanolisobutyl-POSS, and a polar silicone, poly(dimethyl-co-methylvinyl-co-methyl, 2-diphenyl phosphine oxide ethyl) siloxane (PDMS-PO), spread as Langmuir monolayers at the air/water interface are used to examine the surface phase behavior and aggregation of trisilanolisobutyl-POSS as a function of silicone composition. Analyses of the surface pressure-area per monomer (Pi-A) isotherms in terms of the collapse pressures and excess Gibbs free energies of mixing indicate the monolayers form slightly negative deviation mixtures. Direct observations of surface morphology with Brewster angle microscopy in the collapsed regime reveal that the governing factor for aggregation is the collapse Pi of the component with a stronger affinity for water. In trisilanolisobutyl-POSS/PDMS-PO blends, POSS aggregates as discrete domains and does not coalesce into larger aggregates or networklike structures for <80 wt % POSS, a feature that is vastly different from a previous study of POSS blended with regular poly(dimethylsiloxane).
authors.affiliation: Department of Chemistry and the Macromolecules and Interfaces Institute, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA.
authors.forename: Hyong-Jun
authors.initials: HJ
authors.lastname: Kim
authors.forename: Jianjun
authors.initials: J
authors.lastname: Deng
authors.forename: Jennifer Hoyt
authors.initials: JH
authors.lastname: Lalli
authors.forename: Judy S
authors.initials: JS
authors.lastname: Riffle
authors.forename: Brent D
authors.initials: BD
authors.lastname: Viers
authors.forename: Alan R
authors.initials: AR
authors.lastname: Esker
mesh_terms: D000388:Air; D004129:Dimethylpolysiloxanes / Q000737:chemistry*; D006860:Hydrogen Bonding; D008956:Models, Chemical; D015394:Molecular Structure; D009757:Nylons / Q000737:chemistry; D017646:Organosilicon Compounds / Q000737:chemistry*; D010720:Phosphines / Q000737:chemistry*; D012828:Silicones / Q000737:chemistry; D013816:Thermodynamics; D014867:Water / Q000737:chemistry*
chemical_list: D004129:Dimethylpolysiloxanes; D009757:Nylons; D017646:Organosilicon Compounds; D010720:Phosphines; D012828:Silicones; C085707:poly(dimethylsiloxane)-polyamide copolymer; C510837:trisilanolisobutyl-POSS; D014867:Water