Controllable Coordination Polymerization Of Polar Reactive Monomers And Non-Polar Monomers

Introducing polar groups to non-polar polymers can effectively improve the properties of polymers.Coordination polymerization of polar and nonpolar monomers is the most simple and direct method,because in this process,the tacticity of the copolymers,the composition and sequence distribution of the copolymers,the types of polar substituents etc can be easily controlled,which have show great influence on the properties of the copolymers.In the past few years,great progress has been made in the copolymerization of polar with non-polar monomers catalyzed by rare-earth metal complexes.However,different types of polar groups show complicated poisoning effects.In this thesis,a series of reactive monomers which could polymerize but do not poison the catalysts were designed,the coordination(co)polymerization behavior catalyzed by rare-earth metal complexes was investigated,and the post-polymerization modification reactions were preliminary explored.Researches are listed as follows.(1)Three types of 2-(4-halophenyl)-1,3-butadiene monomers were designed and synthesized,which could polymerize with high cis-1,4-selectivity using ?-diketiminato yttrium dialkyl complex(cis-1,4-content>98%).The halogen substituents would not poison the catalyst.When carrying out the copolymerization of 2-(4-halophenyl)-1,3-butadiene with isoprene,the random copolymers could be obtained.The introduction of halogen substituents did not decrease the cis-1,4-selectivity according to the IH NMR spectra.Perfect alternating copolymers of ethylene-halostyrene could be obtained after the hydrogenation of cis-l,4-poly(2-XPB)s.Poly(ethylene-alt-p-vinyl benzoic acid)could be obtained via lithium-halide exchange reaction,thus further post-polymerization modification of the polymers was realized.(2)A BN aromatic vinyl monomer(BN2VN)was synthesized and the influence of the ligand structure of the rare-earth metal catalysts on the polymerization behaviors was investigated.The fluorenyl scandium dialkyl complex bearing a 2,4,6-trimethylphenyl substituted NHC side arm was completely inert to the polymerization.Switching to isopropyl or methyl substituents,only atactic polymers could be obtained.When using a less steric hindered pyridinylmethylfluorenyl scandium dialkyl complex,syndiotactic poly(BN2VN)could be obtained.Treatment the polymer with H2O2 under basic condition,highly syndiotactic poly(vinyl alcohol)with rr=90%could be synthesized,which indirectly proves that the syndiotacticity of poly(BN2VN)is rr=90%.Therefore,highly syndiotactic poly(vinyl alcohol)and poly(BN2VN)are important intermediates for the preparation of various functional syndiotactic polymers.(3)A silylether-protected conjugated diene monomer(IPOTBS)was synthesized.When using PNP-type tridentate carbazolyl yttrium dibenzyl complex,highly cis-1,4-regular homo-poly(IPOTBS)and copolymer of IPOTBS with isoprene or butadiene were obtained(cis-1,4-content>98%).cis-1,4-Regular hydroxyl functionalized polydienes can be obtained when removing the protective groups in the polymers using tetrabutyl ammonium fluoride(TBAF).Hydroxyl functionalized polymers can be co-crosslinked with diisocyanates and diols,obtaining crosslinked polymers with adjustable properties.This work provides a common method for the synthesis of various functionalized polydienes with high cis-1,4-regularities.