Ring-opening metathesis and metallocene polymerizations of cyclohexenyl norbornene and cyclopolymerization of dipropargyl fluorene

Wassana Apichatachutapan

Abstract

Optimized ring-opening metathesis polymerization (ROMP) conditions for cyclohexenyl norbornene (CHNB) have been determined. ROMP of CHNB was carried out with bis(tricyclohexylphosphine)benzylidene ruthenium(IV) dichloride and ruthenium trichloride hydrate. ROMP with 0.0027 mol-% ruthenium benzylidene at room temperature gave CHNB conversions ranging from 97 to 99% with gel times of ca. 24 min. With ruthenium trichloride hydrate and using ethanol as a dissolution aid, only 60-80% conversions with gel times of ca. 43 min occurred at 55-60°C. All polyCHNBs exhibited temperatures of 5% weight loss at ca. 420°C and 430°C under nitrogen and air atmospheres, respectively. Addition polymerization of cyclohexenyl norbornene (CHNB) was carried out with rac -ethylenebis(indenyl)zirconium(IV) dichloride in the presence of methylaluminoxane cocatalyst. PolyCHNB prepared by addition polymerization (add-polyCHNB) was compared to polyCHNB prepared by Ru-catalyzed ring-opening metathesis polymerization (ROMP-polyCHNB). All samples of add-polyCHNB exhibited similar thermal degradation patterns and glass transition temperatures (T g ) at ca. 106°C, but no melting points. Copolymers of CHNB and 4-methyl-1-pentene or 1-hexene were prepared under the same conditions. Most copolymers were soluble in chloroform, toluene and dichlorobenzene. Cyclopolymerization of dipropargyl fluorene was carried out with molybdenum(V) chloride at various reaction conditions. Solid state 13 C NMR analysis confirmed the formation of unsaturated six-membered rings and conjugated double bonds along the polymer backbone. FTIR analysis indicated changes in cis-trans contents in polyDPFs obtained under different reaction conditions. Despite being non-crystalline (by WAXD), the obtained polymers were insoluble in most organic solvents. All poly(dipropargyl fluorene)s exhibited a two-step thermal degradation pattern. Diallyl fluorene was ring-closed with bis(tricyclohexylphosphine)benzylidine ruthenium(IV) dichloride. The attempts for addition polymerization of the ring-closed product (9-spirocyclopentenyl fluorene) were made using rac -ethylenebis(indenyl)zirconium(IV) dichloride in the presence of MAO; however, no polymer was obtained. (Abstract shortened by UMI.)