摘要
采用2种结构不同的配体,与过渡金属Ti、Zr、Ni、Pd的氯化物反应得到8种[N,P]型非茂过渡金属催化剂.通过研究配体结构、中心金属原子及主要聚合条件对乙烯/丙烯共聚合行为的影响,优化出催化剂Cat.L2-Ti,其催化乙烯/丙烯共聚合的活性高,所得共聚物中丙烯插入量达11.5 mol%,共聚物Mw高达2.75×105 g/mol.由核磁共振(13C-NMR)、示差扫描量热法(DSC)与广角X射线衍射(WAXD)结果表明共聚物分子链是以乙烯单元为主,乙烯单体一部分以聚乙烯长链段存在,一部分与丙烯单体无规共聚生成了乙烯/丙烯无规共聚物;同时FTIR表明聚丙烯长链段对应的红外特征峰没有出现,DSC结果也表明聚丙烯链段对应的熔点也没有出现,说明丙烯单元未形成聚丙烯长链段. DSC分析表明随着共聚物中丙烯单体插入量增加,聚乙烯长链段显示的熔点渐渐降低,当丙烯插入量达11.5 mol%时,共聚物的熔融峰不明显. WAXD分析表明即使丙烯插入量达11.5 mol%时,没有聚丙烯长链段的结晶衍射峰,但是聚乙烯长链段的结晶衍射峰强度随丙烯插入量增加而减弱.当丙烯插入量达11.5 mol%时,共聚物的结晶衍射峰明显变弱.这些结果证实[N,P]型非茂过渡金属配合物催化乙烯、丙烯共聚可获得PE-b-P(E/P)多嵌段共聚物.
Eight [N,P]-type non-metallocene catalysts were synthesized successfully via the reaction between two kinds of ligands carrying different electronic effect groups and chloride compounds of transition metals Ti, Zr, Ni and Pd. Catalyst Cat.L2-Ti exhibited the highest catalytic activity toward ethylene/propylene copolymerization thanks to the combined effects exerted by ligand structure, central atomic species, and polymerization conditions on copolymerization behavior of ethylene with propylene. The copolymer product achieved a high Mw up to 2.75 × 10^5 g/mol as measured by GPC, and 13C-NMR test suggested that the content of propylene insertion within copolymer backbone reached 11.5 mol%. Characterization with 13C-NMR, DSC, and WAXD demonstrated that macromolecular chains of the obtained copolymer were composed mainly of ethylene units existing as long-chain segments, while some other ethylene units formed random segments with copolymerized propylene monomers. Melting point of the copolymer decreased along with the increasing amount of propylene insertion, and so did the peak intensity in crystal diffraction of polyethylene segments. At the greatest insertion amount of propylene of 11.5 mol%, the melting peak could hardly be noted on DSC curve, and the peak intensity in crystal diffraction weakened markedly as well. Moreover, neither the characteristic peak in FTIR spectra nor the diffraction peak on WAXD patterns showed up for the long segments of polypropylene. Together with the missing melting peak of isotactic polypropylene on DSC curve, it was inferred that polypropylene hardly existed in the long-chain form basically. All these results confirmed the effective role played by [N,P]-type non-metallocene catalysts in the preparation of multi-block copolymers PE-b-P(E/P).
作者
王秋璨
周阳
张娇娇
于洪超
张少蒙
付瑶
时子海
李红明
夏碧华
黄启谷
Qiu-can Wang;Yang Zhou;Jiao-jiao Zhang;Hong-chao Yu;Shao-meng Zhang;Yao Fu;Zi-hai Shi;Hong-ming Li;Bi-hua Xia;Qi-gu Huang(State Key Laboratory of Effective Utilization of Chemical Resources, Key Laboratory of Carbon Fiber and Functional Polymers of Ministry of Education, College of Materials Science and Engineering,Beijing University of Chemical Technology, Beijing 100029)
出处
《高分子学报》
SCIE
CAS
CSCD
北大核心
2019年第2期124-134,I0003,共12页
Acta Polymerica Sinica
基金
国家自然科学基金(基金号U1462102)资助项目
关键词
非茂过渡金属催化剂
乙烯
丙烯
共聚合
多嵌段共聚烯烃
Non-metallocene catalysts
Ethylene
Propylene
Co-polymerization
Multi-block copolymers
