Copolymerization Of Functional ?-Olefins With Isoprene By Half-Sandwich Scandium Complexes

Functionalization is the most effective way to achieve high performance of rubber materials.At present,the main synthetic methods of functionalized rubber materials are post-functionalization and direct-polymerization.The post-functionalization process is tedious and the distribution of functional groups are uncontrollable.The copolymerization of functional monomers with conjugated diene such as butadiene and isoprene can prepare rubber materials in one-pot,which is the best method for preparing functional rubber materials.In this thesis,the functionalized polyisoprene materials with controllable composition and structure were prepared by copolymerization of isoprene with functionalized?-olefin containing bromine and amine groups.1.The polymerization of 10-bromo-1-decene?BrDC?by half-sandwich scandium complexes?C₅Me₄SiMe₃?Sc?CH₂C₆H₄NMe₂-o?₂?1?,?C₅H₅?Sc?CH₂C₆H₄NMe₂-o?₂?3?and?C₅H₅?Sc?CH₂SiMe₃??THF??4?did not give any polymer.The polymerization of BrDC by?C₅Me₄SiMe₃?Sc?CH₂SiMe₃?₂?THF??2?afforded the atactic polymer with high activity.The molecular weight of the obtained BrDC polymer was 8000 because of severe chain transfer reaction in the polymerization of BrDC.The isoprene/BrDC copolymers with the BrDC insertion rate from 4 mol%to 17 mol%were prepared by adjusting the amount of monomers in the copolymerization of isoprene with BrDC by scandium complex 2.The molecular weight of BrDC/isoprene copolymers showed multimodal distribution,because chain transfer reaction was not inhibited in the copolymerization of BrDC and isoprene.2.The polymerization of 5-?N,N-diethylamino?-1-pentene?DEAP?by scandium complexes 2 and 4 did not give any polymer The polymerization of DEAP by scandium complexes 1 and 3 afforded the atactic polymers.The molecular weight of the obtained DEAP polymers were less than 1000 because of severe chain transfer reaction in the polymerization of DEAP.The catalytic activity of 3 was much lower than that of 1.The copolymerization of DEAP with isoprene by scandium complex 1 afforded the isoprene/DEAP random copolymers with different isoprene contents and a predominant3,4-structure with high activity.The DEAP content in the isoprene/DEAP copolymers were from 6 mol%to 49 mol%.The molecular weight and molecular weight distribution of the obtained isoprene/DEAP copolymers by 1 was 10000⁴5000 and 1.5².1,respectively.The chain transfer reaction was restrained to some extent in the copolymerization of DEAP with isoprene by scandium complex 1.The isoprene/DEAP random copolymers with different compositions prepared by scandium complex 1 had a glass transition temperature?T_g=-4?^-31??,which decreases with the increase of DEAP content.The copolymerization of DEAP with isoprene by scandium complex 3 afforded the isoprene/DEAP random copolymers with different isoprene contents and a predominant cis-1,4-structure.The DEAP content in the isoprene/DEAP copolymers were from 2 mol%to 28 mol%,and cis-1,4-selectivity was up to 95%.The molecular weight and molecular weight distribution of the obtained isoprene/DEAP copolymers by 3 was 28000⁸3000 and 1.7¹.9,respectively.The chain transfer reaction was restrained in the copolymerization of DEAP with isoprene by scandium complex 3.The isoprene/DEAP random copolymers with different compositions prepared by scandium complex 1 had T_g of-61?.