Synthesis and characterization of organometallic catalysts = 다양한 폴리올레핀을 위한 유기금속 촉매의 합성과 규명

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A new synthetic strategy of developing novel isospecific unbridged metallocene polypropylene catalytic system that can be in-situ generated during the MAO-assisted activation step was demonstrated by using amine-functionalized zirconocene $[1-(p-Me_2NC_6H_4)-3,4-Me_2C_5H_2]_2ZrCl_2$ that has racemic $C_2$ -symmetric nature in the solid state. This precatalyst shows high isospecificity in propylene polymerization under MAO activation but gives complete atactic polypropylene under $[Ph_3C][B(C_6F_5)_4]$ activation. This phenomenon is originated from the inhibition of the rigand rotation during propagation via the Lewis acid-base interaction between basic amine in catalyst and acidic sites in [Me-MAO]-. In order to establish the scope of the current synthetic strategy and obtain further information of this system, $-NEt_2$, -OMe, and -SMe substituted unbridged bis-zirconocenes were also synthesized and their catalytic behaviors in propylene polymerization were obtained. The isoselectivity of these complexes are in order of Lewis basicity, $-NMe_2$ > -OMe > -SMe. The well-defined, novel dinuclear group 4 metal complexes $[4,4``-(C_6H_4)_2(C_5Me_4)_2][CpZrX_2]_2$ (X = Cl, Me), $[4,4``-(C_6H_4)_2(C_5Me_4)_2][TiCl_3]_2$, and $[4,4``-(C_6H_4)_2(C_5Me_4)_2][Ti(O-2,6-iPr_2Ph)Cl_2]_2$ were synthesized and their ethylene and styrene polymerization behaviors were investigated. These complexes exhibit an increase of molecular weight as well as comparable or even higher catalytic activity than their mononuclear analogues, $(C_5Me_4Ph)CpZrX_2$ (X = Cl, Me), $(C_5Me_4biPh)CpZrCl_2$, $(C_5Me_4Ph)TiCl_3$, and $(C_5Me_4Ph)Ti(O-2,6-iPr_2Ph)Cl_2$. To endow the existing biphenylene group with flexibility that can provide better solubility as well as additional metal-metal interactions and at the same time to keep each metal center being highly active by minimizing a steric hindrance between two active centers, dinuclear zirconocenes containing bis(cyclopentadienyl) ligands derived f...
Advisors
Do, Young-Kyuresearcher도영규researcher
Description
한국과학기술원 : 화학과,
Publisher
한국과학기술원
Issue Date
2006
Identifier
258169/325007  / 020025051
Language
eng
Description

학위논문(박사) - 한국과학기술원 : 화학과, 2006.8, [ xii, 171 p. ]

Keywords

polypropylene; polyethylene; organometallic catalyst; Olefin Polymerization; polystyrene; 폴리스티렌; 폴리프로필렌; 폴리에틸렌; 유기금속 촉매; 올레핀 중합

URI
http://hdl.handle.net/10203/31674
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=258169&flag=dissertation
Appears in Collection
CH-Theses_Ph.D.(박사논문)
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