title: Covalent molecular assembly of multilayer dendrimer ultrathin films in supercritical medium.
abstract: Ultrathin films containing dendrimers are fabricated on amine- and anhydride-derivatized silicon dioxide surface through alternate layer-by-layer (LbL) assembly of pyromellitic dianhydride (PMDA) and poly(amidoamine) (PAMAM) dendrimer in supercritical carbon dioxide (SCCO2) with interlayer linkage established by covalent bonds. X-ray photoelectron and UV-visible absorption spectroscopies, atomic force microscopy (AFM), and ellipsometry were employed to study the interfacial chemistry, growth, morphology, and thickness of the assembled film. XPS analysis suggests that the PMDA/PAMAM interlayer covalent bond is established to completion, and functional surfaces for immobilization of the next layer are available after deposition of each layer. UV-visible absorption and ellipsometry revealed layer-by-layer growth of the film. The functional property film as a porous matrix was manifested in the reduction of the refractive index upon introduction of the dendrimer.
authors.affiliation: Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive, 4117576 Singapore.
authors.forename: Sreenivasa Reddy
authors.initials: SR
authors.lastname: Puniredd
authors.forename: M P
authors.initials: MP
authors.lastname: Srinivasan
mesh_terms: D002245:Carbon Dioxide; D050091:Dendrimers; D008567:Membranes, Artificial; D011073:Polyamines / Q000138:chemical synthesis*
chemical_list: D050091:Dendrimers; D008567:Membranes, Artificial; C104700:PAMAM Starburst; D011073:Polyamines; D002245:Carbon Dioxide