Hyperbranched polymer films and dendrimers : their chemistry and applications /
The research in this dissertation examines the chemistry and applications of dendritic polymers; specifically, hyperbranched polymer thin films and dendrimers. We examined hyperbranched, fluorinated and unfluorinated poly(acrylic acid) (PAA) films on gold substrates, poly(amidoamine) (PAMAM) dendrit...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1999.
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| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=731681781&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | The research in this dissertation examines the chemistry and applications of dendritic polymers; specifically, hyperbranched polymer thin films and dendrimers. We examined hyperbranched, fluorinated and unfluorinated poly(acrylic acid) (PAA) films on gold substrates, poly(amidoamine) (PAMAM) dendrites minelayers and dendrimer-alkanethiol mixed manslayers on gold substrates, PAMAM dendrimer/poly(anhydride) and poly(iminopropane-l,3-diyl) (Cascade) dendrimer/poly(anhydride) multilayer films on silicon, gold, and aluminum substrates, PAMAM dendrimer/metal-ion composites, and PAMAM dendrimer-encapsulated metal nanoclusters in solution and on electrode surfaces. Hyperbranched PAA films have pH-dependent blocking abilities: at low pH PAA films effectively passivate Au electrodes while at high pH they are open and permeable. Fluorinated PAA films are far less permeable at any pH. Dendrimers ranging from generation 4 to 8 (G4-G8) can form highly stable and nearly close-packed manslayers and mixed minelayers with hexadecanethiol (C16SH) on surfaces. Moreover, dendrimers embedded within C I6SH can act as pates of molecular dimension that control intradendrimer mass transfer of ions. Dendrimer/poly(anhydride) multipliers on surfaces were synthesized and their permeability was investigated. These composite membranes exhibit fully reversible, pH-switchable permselectivity for both cationic and anionic probe molecules because of their pH-dependent electrostatic properties. After heating, such films become highly blocking over the pH range studied due to thermally induced interdendrimer imidization, and other reactions. Finally, we show that PAMAM dendrimers can act first as templates for the preparation transition-metal nanoclusters, and subsequently as stabilizers. Dendrimers quantitatively complex many transition-metal ions, including Cu²⁺, Pt²⁺, Pd²⁺, Ru³⁺, and Ni²⁺ within their interiors. Chemical reduction of such nanocomposites results in formation of dendrimer-encapsulated metal nanoclusters. Dendrimer-encapsulated Ag and Au particles can be synthesized by displacement reactions. Dendrimer-encapsulated bimetallic nanoclusters can be prepared by sequential loading and reduction of two different types of ions, or they can be prepared by simultaneous co-complexation of two different metal ions followed by a single reduction reaction. Intradendrimer nanoparticles can also be prepared- by displacement cross-reactions. Dendrimer-encapsulated Pt or Pd clusters can be used as electrocatalysts for O₂ reduction and as homogeneous catalysts for the hydrogenation of alkanes. Importantly, the catalytic activity and selectivity can be controlled by adjusting the size (generation) of the dendrites. |
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| Item Description: | Vita. "Major Subject: Chemistry". |
| Physical Description: | xix, 236 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 204-230). |