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20151201120127.0 |
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100427s2010 txu sbm 000 0 eng d |
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|a (OCoLC)ocn609622706
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|a (OCoLC)609622706
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|a (TxCM)http://hdl.handle.net/1969.1/ETD-TAMU-1433
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| 040 |
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|a TXA
|c TXA
|d UtOrBLW
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| 049 |
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|a TXAM
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| 099 |
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|a 2007
|a Dissertation
|a 1969.1/ETD-TAMU-1433
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| 100 |
1 |
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|a Choi, Wonsook.
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| 245 |
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|a Mechanistic studies of the metal catalyzed formation of polycarbonates and their thermoplastic elastomers /
|c by Wonsook Choi.
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| 264 |
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|a [College Station, Tex.] :
|b [Texas A&M University],
|c [2010]
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| 300 |
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|a 1 online resource.
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| 336 |
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|a text
|b txt
|2 rdacontent
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|a computer
|b c
|2 rdamedia
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| 338 |
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|a online resource
|b cr
|2 rdacarrier
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| 500 |
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|a "Major Subject: Chemistry"
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| 500 |
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|a Title from author supplied metadata (automated record created 2010-03-12 12:08:51).
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| 502 |
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|b Doctor of Philosophy
|c Texas A&M University
|d 2007
|o http://hdl.handle.net/1969.1/ETD-TAMU-1433
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|a Includes bibliographical references.
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|a Text (Dissertation)
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|a Studies concerning the formation of industrially useful polycarbonates are the focus of this dissertation. Of particular importance is the biodegradable polymer, poly(trimethylene carbonate) which has a wide range of medical applications. The production of polycarbonates can be achieved by the ring-opening polymerization of cyclic carbonate, or the copolymerization of carbon dioxide and oxiranes or oxetanes. For the production of polycarbonates from these monomers, Schiff base metal complexes have been designed, synthesized, and optimized as catalysts. Detailed kinetic and mechanistic studies have been performed for the ring-opening polymerization of cyclic carbonates, as well as the copolymerization of carbon dioxide and oxiranes or oxetane. In addition, the copolymerization of cyclic carbonates and cyclic esters to modify the mechanical and biodegradable properties of materials used for medical devices has been studied using biocompatible metal complexes. In the process for ring-opening polymerizations of trimethylene carbonate or lactides, Schiff base metal complexes (metal = Ca(II), Mg(II) and Zn(II)) have been shown to be very effective catalysts to produce high molecular weight polymers with narrow polydispersities. Kinetic studies demonstrated the polymerization reactions to proceed via a mechanism first order in [monomer], [catalyst], and [cocatalyst] if an external cocatalyst is applied, and to involve ring-opening by way of acyl-oxygen bond cleavage. The activation parameters ([Delta]H [subfield delimiter], [Delta]S [subfield delimiter] and [Delta]G [subfield delimiter]) were determined for ringopening polymerization of trimethylene carbonate, ring-opening polymerization of lactides, and copolymerization of trimethylene carbonate and lactide. In the process for copolymerization of carbon dioxide and oxetane, metal salen derivatives of Cr(III) and Al(III) along with cocatalyst such as n-Bu4NX or PPNX (PPN = bis(triphenylphosphine)iminium, and X = Br, Cl and N3) have been shown to be effective catalysts to provide poly(trimethylene carbonate) with only trace amount of ether linkages. The formation of copolymer is proposed not to proceed via the intermediacy of trimethylene carbonate, which was observed as a minor product of the coupling reaction. To support this conclusion, ring-opening polymerization of trimethylene carbonate has been performed and kinetic parameters have been compared with those from the copolymerization of carbon dioxide and oxetane.
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|a Electronic resource.
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|a Major chemistry.
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|a Thermoplastic Elastomers
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| 653 |
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|a Medical Materials
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| 653 |
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|a Polycarbonates
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|a Biodegradation
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| 653 |
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|a Poly(trimethylene Carbonate)
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| 653 |
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|a Biometal catalysts
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| 653 |
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|a Copolymers
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|a Poly(lactide)
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| 653 |
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|a Ring-opening Polymerization
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| 700 |
1 |
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|a Darensbourg, Donald J.,
|e thesis advisor.
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| 856 |
4 |
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|u http://hdl.handle.net/1969.1/ETD-TAMU-1433
|z Link to OAK Trust copy
|t 0
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| 948 |
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|a cataloged
|b h
|c 2010/4/27
|d c
|e jhennen
|f 10:54:54 am
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| 994 |
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|a C0
|b TXA
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| 999 |
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|a MARS
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| 999 |
f |
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|i 59e654cc-071a-3cd7-9f0e-f024aa191a7f
|t 0
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| 952 |
f |
f |
|a Texas A&M University
|b College Station
|c Electronic Resources
|d Available Online
|t 0
|e 2007 Dissertation 1969.1/ETD-TAMU-1433
|h Other scheme
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| 998 |
f |
f |
|a 2007 Dissertation 1969.1/ETD-TAMU-1433
|t 0
|l Available Online
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