| The polymerizations of bio-based olefins or polar olefins have been successfully achieved by using a series of rare earth metal complexes including diiminophosphinato rare earth complexes la-lc,2a-2b;pyridyl-methylene-fluorenyl rare earth complexes 3a-3c;pyridyl-methylene-’Bufluorenyl rare earth complexes 4a-4c;β-diketiminato yttrium complex 5;bis(imino)aryl gadolinium complex 6;bis-(phosphino)carbazolide yttrium complex 7;bis(phosphinophenyl)amido yttrium complex 8;half-sandwich complexes 9,10,11a-11c;non-Cp triazine ligated scandium complex 12;methylsubstituted NHC fluorenyl scandium complex 13;isopropyl-substituted NHC fluorenyl scandium complex 14;trimethylphenyl-substituted NHC fluorenyl scandium complex 15;ansa-bis(benz[e]indenyl)rare-earth metal complexes 16a-16f;ansa-bisindenylrare-earth metal complexes 17a-17f in this dissertation.The polymerization activity,stereoregularity,regioselectivity,molecular weight,sequence distribution and polar monomer insertion rate were studied detailedly and DFT simulations are employed to illustrate the mechanisms.In addition,the post-functionlization reaction of the polymer containing the reaction groups was performed to prepare a series of functionalized stereoregular polymers,and the physical,mechanical of polymer were preliminarily studied.The details are listed as bellow:(1)Coordination polymerization of renewable 1-phenyl-1,3-butadiene(1PB)synthesized via Wittig reaction has been carried out using complexes 1b,2a,3,4,5,6,7 and 8.Complexes 1b,2a,3a,3b,and 4a,4b,under the activation of[Ph3C][B(C6F5)4]and AliBu3,show high activities as well as higher than 96.6%3,4-regioselectivities,of which 1b and 2a are nonstereoselective,giving atactic 3,4-poly(1PB),while 3a,3b and 4a,4b exhibit distinguished syndioselectivities(rrrr≥ 95.3%).However,complexes 3c,4c and 5-7 are inactive for 1PB polymerization.On the contrary,the cis-1,4selective complex 8 exhibits syndio-(rrrr≥ 96.1%)and 3,4-regio-(>99%)selectivity for 1PB polymerization and copolymerization of 1PB with IP and gives diblock copolymer.Hydrogenation of a syndiotactic 3,4-poly(1PB)affords a syndiotactic poly(4-pheny1-1-butene)elastomer with a Tg of 17℃.The cationic cyclization transfers a syndiotactic 3,4-poly(1PB)into a rigid cyclized polyolefin with a Tg as high as 327℃.Density functional theory(DFT)simulations are employed to illustrate the mechanisms.(2)Coordination polymerization of renewable(E)-4,8-dimethyl-1,3,7-nonatriene(DMNT)synthesized via Wittig reaction has been performed using complex 3a,9,1a1c,2a-2b,5 and 7.Fluorenyl scandium complexes 3a and 9,activated by[Ph3C][B(C6F5)4]and AliBu3,are moderately active and show perfect 1,2-regioselective(1,2>99%).Conversely,asymmetric diiminophophinato complexes la-1c promote the DMNT polymerization to produce high trans-1,4 regulated products with the activity trend:Sc<Lu<Y.Complexes 2a-2b,7,5 are virtually inactive for the DMNT polymerization although they are highly active in isoprene polymerization.A diblock copolymer bearing 3,4-poly isoprene block and trans-1,4-poly(DMNT)block is obtained using complex lc in one-pot reaction.Hydrogenation of trans-1,4poly(DMNT)affords an elastomer with a Tg of-10℃.The epoxidation reaction of trans-1,4-poly(DMNT)with 3-chloroperbenzoic acid transfers the pendant double bonds in the cis configuration into the epoxy groups.The cycloxidizing polymer shows high elongation-at-break above 1970%under 1.33 MPa tensile strength.(3)We present new racemic ansa-bis(benz[e]indenyl)rare-earth metal complexes 16a-16f and ansa-bisindenyl rare-earth metal complexes 17a-17f and their high activity and perfect isoselectivity(mmmm>99%)for the polymerization of unmasked paramethoxystyrene without any activators.These excellent properties are still maintained at 120℃.mata-methoxystyrene,3,5-dimethoxystyrene,para-methylthiostyrene,paravinylphenyldimethylsilanol,para-methylstyrene and styrene were also polymerizd into perfect isotactic product with high activites.Moreover,the copolymerizations of paraand meta-methoxystyrenes with styrene catalyzed by complex 16b give gradient and random copolymers,respectively.The insertion rate of polar monomers could be readily tuned in the range of 0-100 mol%by changing their loading ratios.The resultant isotactic polar polystyrenes are quantitatively transformed into hydroxyl or methylsulfonyl polystyrenes with high Tgs.DFT calculations reveal the isospecific mechanism.(4)The copolymerization of E with 6-phenoxy-l-hexene(POH)by using CGCtype scandium complexes 15,3a and half sandwich scandium complexes 9,10.Complex 15,activated by[Ph3C][B(C6F5)4]and AliBu3,shows high activity(1.4 × 105 g molSc-1 h-1)and gives E-POH copolymer with 0.7%POH.Under identical conditions,the activity of 3a drops to 0.1 × 105 g molSc-1 h-1.In contrast,the half sandwich scandium precatalyst 9 displays a much higher activity(8.1 × 105 g molSc-1 h-1)and affords a copolymer with 7.0 mol%POH.The highest activity(23.4 × 105 g molSc-1 h-1)and incorporation ratio(16 mol%)were achieved by 10.Density functional theory(DFT)simulations are employed to illustrate the mechanisms for the polymerization activity and polar group incorporation ratio from kinetic,thermodynamic and geometric viewpoints.The resultant copolymer is readily transformed into brominated product,and then ethylene-based ionomers containing ionic liquid functionality,featuring excellent mechanical properties.The ionomers behave like thermoplastic elastomers and show high stress values up to 23.5 MPa under elongation-at-break above 835%.(5)Ethyl vinyl ether(EVE)polymerizations by rare-earth metal complexes were studied.The metallocene complexes 9,3a-3c,14 activated by[Ph3C][B(C6F5)4]displayed extremely high catalytic activities(≤ 1.50 × 106 g mol-1 h-1)for EVE polymerization at 25℃.The non-metallocene complexes 7,1b,5 were nearly inert under the same conditions.The neutral complex 9,AliBu3 and 9/AliBu3 were completely inactive for EVE polymerizadtion.Nevertheless,borate or boraate/AliBu3 initiated EVE polymerization in moderate activities to give polymers with low molecular weights and broad molecular weight distribution.The resultant molecular weights produced by 9/[Ph3C][B(C6F5)4]increased from 1.37 × 104 to 19.3 × 104 g mol1 with the temperature declining from 25 to-45℃.The addition of 10 equivalents of AliBu3 to the binary system 9/[Ph3C][B(C6F5)4]resulted in the higher molecular weight product(32.5 × 104 g mol-1)at-45℃.With the molar ratio of EVE-to-9 increased from 2000:1 to 10000:1,the resultant molecular weight reached 107.3 × 104 g mol-1,but the catalytic activity dropped dramatically from 7.60 × 105 to 0.57 × 105 g molSc-1 h-1.The dicationic species formed by the reaction of 9 with 2 equivalents of[Ph3C][B(C6F5)4]displayed high catalytic activity for EVE polymerization and gave high molecular weight product in the presence of AliBu3.(6)Isobutene(co)polymerizations by rare-earth metal cationic complexes were studied.The half-sandwich scandium and lutetium complexes 11a and 11b activated by one equivalent of[Ph3C][B(C6F5)4],displayed high activity for isobutene polymerization at-30℃.Its yttrium analogue 11c,the constrained geometry complexes 3a and 14 and the metallocene 17f showed lower activities.Another half-sandwich scandium complex 10 and non-Cp complex 12 were inert.The resultant molecular weights produced by cationic initiator 11a increased from 2.45 × 104 to 27.8 × 104 g/mol with temperature declining from 20 to-50℃.Despite increment of isobutene/lla mole ratio from 3000:1 to 30000:1,the resultant molecular weights still fell within the scope of 20.0 × 104-25.0 × 104 g/mol.The cationic species lla/[Ph3C][B(C6F5)4]is not an effective initiator for isobutene copolymerization with isoprene,but if the cationic species is first treated by isobutene or the dicationic species lla/2[Ph3C][B(C6F5)4]is applied,the copolymerization can reach a high conversion. |
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