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Title: Homogeneous catalysts for the synthesis of oxygenated polymers
Author: Thevenon, Arnaud
ISNI:       0000 0004 7229 3471
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2017
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This thesis describes the synthesis and characterisation of novel mono and dinuclear homogenous [Zn(II)] and [In(III)] metal complexes. Their applications as catalysts for CO2/epoxide or epoxide/anhydride ring opening copolymerisation and lactide ring opening polymerisation to generate polycarbonates and polyesters, respectively, are also reported. Chapter 3 reports the first indium phosphasalen catalysts for CO2/cyclohexene oxide ring opening copolymerization. The catalysts are active at 1 bar pressure of CO2 and are most effective without any co-catalyst. It is also possible to use the complexes to isolate and characterise the key intermediates in the catalytic cycle. Kinetic and spectroscopic analyses show that polymerisation proceeds via a rare cis-mononuclear coordination- insertion mechanism. Chapter 4 describes a series of mono and dinuclear zinc macrocycle catalysts with very high activities for the racemic lactide ring opening polymerisation. In most cases, the dinuclear zinc catalysts significantly out-perform the mono-zinc homologue. In addition, kinetic and spectroscopic investigations suggest a role for the ligand conformation in mediating rate. The catalysts perform very well under immortal conditions and operate at low catalyst loading, whilst conserving high activities. Chapter 5 presents four dinuclear zinc acetate salen catalysts for the ring opening copolymerisation of CO2/cyclohexene oxide and phthalic anhydride/cyclohexene oxide. The catalysts show moderate activities for CO2/epoxide copolymerisation but are highly active for epoxide/anhydride copolymerisation. Structure/activity relationship studies reveal that the more flexible and electron donating ligand displays the highest activity. Poly(ester-b-carbonate)s are also afforded using the most active catalyst in terpolymerisations of anhydride/epoxide/CO2.
Supervisor: Williams, Charlotte K. Sponsor: Climate KIC
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Green Chemistry ; Inorganic Chemistry ; Chemistry ; Phosphasalen ; Salen ; Dinuclear ; Ring Opening Copolymerization ; Polycarbonate ; Stereoselectivity ; Mechanistic studies ; Ring Opening Polymerization ; Isoselectivity ; Lactide ; Indium ; Zinc ; Mononuclear ; Homogeneous catalysis ; CO2 ; Polyester ; Epoxide