Polymerization Of Myrcene Catalyzed By Half-Sandiwich Scandium Complexes

The study of catalysts suitable for the controlled homo- and copolymerization of biomass monomer myrcene and the relationship between catalyst structures and catalytic properties have both important theoretical and applied values. In this thesis, the relationship between catalyst structures and catalytic properties in the homo- and copolymerization of myrcene with olefins by half-sandwich scandium complexes was systematically analyzed. The development of new organo rare earth metal complexes have high chemistry activity and selectivity and are superior to the existing ones, to achieve a series of well-defined stereochemical and sequential structure (co)polymers.1. Significant ligand influence on the catalytic activity and selectivity has been observed in the polymerization of myrcene by half-sandwich scandium complexes. The Sc complex bearing the larger C5Me4SiMe3 (Cp'ScTHF and Cp'Sc) ligands exihited comparable catalytic activity (10-30 g polymer (mol of Sc)-1 h-1) and stereoselectivity, to afford polymyrcene with oriented 3,4-polymyrcene (Tg=-46 ?). However, the Sc complex bearing the small C5H5 (CpSc) ligands has high catalytic activity (380 g polymer (mol of Sc)-1 h-1) and 1,4-selectivity is up to 98%(Tg=-70 ?). The molecular weight of the obtained myrcene is increased almost linearly as the monomer-to-catalyst ratio increased. These results suggested that the polymerization of myrcene by CpSc possesses quasi-living characters.2. The copolymerization of myrcene with conjugated olefins has been achieved by half-sandwich scandium complexes, to afford different stereochemical and sequential structure copolymers. The copolymerization of myrcene with butadiene by Cp'Sc were achieved, to afford myrcene-butadiene random copolymers with 3,4-polymyrcene (selectivity 74%) and 1,4-polybutadiene (selectivity 86%). The copolymerization of myrcene with butadiene by CpSc were also achieved, to afford myrcene-butadiene random copolymers with 1,4-content of both monomer units (selectivity> 90%). The molecular weight and composition of myrcene-butadiene random copolymers can be effctively regulated by adjusting monomer-to-catalyst ratio and the monomer-to-monomer, respectively. The random copolymers with different composition possess one glass-transition temperature (Tg-60?-95 ?). The block copolymerization of myrcene with styrene has been achieved by Cp'Sc and CpSc. The obtained myrene-styrene copolymers by Cp'Sc contained 3,4-polymyrcene block (selectivity 75%) and syndiotactic polystyrene block, and possess Tg (-37 ?) and melting point (Tm 250 ?). The myrene-styrene block copolymers by CpSc has high 1,4-polymyrcene block (selectivity 97%) and atactic polystyrene block, and possess two Tg (-63 ?,94 ?). The composition of myrene-styrene block copolymers can be effctively regulated by adjusting the monomer-to-monomer ratio.3. The copolymerization of myrcene with ethylene has been achieved by half-sandwich scandium complexes, to afford different stereochemical and sequential structure copolymers. The copolymerization of myrcene with ethylene has been produced by half-sandwich scandium dialkyl complexes. By use of Cp'ScTHF, the myrene-ethylene random copolymers with isolated myrcene and polyethylene blocks were obtained. The obtained random copolymers have controllable composition (myrene units content 9-35 mol%). The obtained random copolymers possess Tg (-63?55 ?) and Tm (108?133 ?) when the content of myrene units is little than 21 mol%. By use of Cp'Sc, the myrene-ethylene block copolymers with controllable composition (My units content 8-62 mol%) possess Tg (-50 ?) and Tm (123 ?).