title: Toughening of nanoporous glasses using porogen residuals.
abstract: Nanoporous glasses are inherently brittle materials that become increasingly fragile with increasing porosity. We show that remarkable increases in fracture energy can be obtained from remnants of the porogen molecules used to create the nanoscale pores. The interfacial fracture energy of approximately 2.6 J m(-2) for dense methylsilsesquioxane glass films is shown to increase by over one order of magnitude to >30 J m(-2) for glasses containing 50 vol.% porosity. The increased fracture resistance is related to a powerful molecular-bridging mechanism that was modelled using bridging mechanics. The study demonstrates that significant increases in interfacial fracture energy may be obtained using strategies involving controlled decomposition of the porogen molecule during processing of nanoporous glasses. The implications are important for a range of emerging optical, electronic and biological technologies that use nanoporous thin films, but are limited by the degradation of mechanical properties with increasing porosity.
authors.affiliation: Department of Materials Science and Engineering, Stanford University, 416 Escondido Mall, Stanford, California 94305-2205, USA.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Maidenberg
authors.forename: Willi
authors.initials: W
authors.lastname: Volksen
authors.forename: Robert D
authors.initials: RD
authors.lastname: Miller
authors.forename: Reinhold H
authors.initials: RH
authors.lastname: Dauskardt
mesh_terms: D001709:Biotechnology / Q000295:instrumentation; D004581:Electronics / Q000295:instrumentation / Q000379:methods; D019544:Equipment Failure Analysis; D005898:Glass / Q000032:analysis / Q000737:chemistry*; D008422:Materials Testing; D036103:Nanotechnology / Q000295:instrumentation / Q000379:methods*; D055095:Optics and Photonics / Q000295:instrumentation; D011108:Polymers / Q000737:chemistry*; D016062:Porosity; D013055:Spectrophotometry, Infrared; D013057:Spectrum Analysis / Q000379:methods; D014965:X-Rays
chemical_list: D011108:Polymers