刷状载体负载FI催化剂制备双峰聚乙烯

Preparation of Bimodal Polyethylene by Brush-like Polymer Supported FI Catalyst

董振

11749202

硕士

化学工程

陈忠仁

2019-05-25

2019-07-12

哈尔滨工业大学

深圳

随着技术不断发展，人们对聚乙烯产品的各方面性能有了进一步的要求，双峰聚乙烯兼具高分子量和低分子量片段的性能，是性能优异的聚乙烯材料。目前主流双峰聚乙烯生产工艺中，单一反应器法生产双峰聚乙烯可以实现两种分子量的聚乙烯材料从分子级别的共混，且单反应器法成本低廉，生产工艺简便。而在现有的工业体系下，要实现催化剂的应用，必须对催化剂进行负载。本文设计使用一种刷状拓扑结构的聚合物来负载FI催化剂进行乙烯聚合。首先使用ATRP与ROMP的方法合成侧链均一的聚合物刷，接着通过叠氮化反应、click reaction、醛胺缩合在末端修饰上苯氧基亚胺配体，最后与金属中心配位，得到刷状拓扑结构负载的催化剂用于乙烯聚合。本文对六种苯氧基亚胺型配体在不同压力下的聚合反应进行了探讨，并且将小分子均相FI催化剂与负载后的催化剂进行对比。通过对比不同配体催化剂的活性，将两种不同的配体按照一定比例修饰在刷状聚合物的末端，负载上金属催化剂，实现在同一个刷的末端负载两种不同活性的FI催化剂，以制备双峰聚乙烯。结果显示，催化剂的活性和得到聚乙烯的分子量与苯氧基亚胺配体R2基团的位阻有关。负载后的非均相FI催化剂与均相小分子催化剂相比，活性并未降低，高压下（1MPa）得到聚乙烯的分子量随着苯氧基亚胺配体R1基团的位阻的增大而降低。压力升高时1号和3号配体催化剂出现了分子量降低的现象。两种不同配体混合负载的FI催化剂在常压下制备出的聚乙烯分子量分布明显变宽，有出现双峰聚乙烯的趋势。通过SEM观测聚乙烯样品，出现了特殊的鱼鳞状片层结构。本文成功实现将FI催化剂负载到刷状拓扑结构载体上，负载后的催化剂在1 MPa压力条件下活性得到很大提升，对后期聚乙烯的加工性能研究做铺垫。

Higher performance are required in polyethylene products with the development of technology. Bimodal polyethylene, combined high molecular weight part and low molecular weight part, is excellent polyethylene material. The processes for producing bimodal polyethylene mainly include melt blending method, series reactor method and single-reactor method. The single-reactor method for producing bimodal polyethylene can realize the blending of two molecular weight polyethylene from the molecular level. Owing to its low cost and simple production process, single-reactor method has become a popular research topic. The catalysts must be supported in the existing industrial system.This paper designed a brush-like polymer as a supporter for FI catalyst. First, polymer brush having a uniform side chain was synthesized by the method of ATRP and ROMP. Then the phenoxyimine ligand was modified at the end of side chain by azidation reaction, click reaction and aldehyde amine condensation. Final metal catalyst was supported by brush-like polymer to carry out polymerization of ethylene. In this paper, six different ligands coped with central metal are designed by phenoxy-imine functionalization of brush side chain. And then, we used these six supported catalysts for ethylene polymerization in different pressures. We compared the homogeneous FI catalysts with the supported catalysts. By comparing the activities of catalysts, different ligands were modified at a certain ratio in the end of brush side chain and then coordinated with metal catalyst. Two kind of FI catalysts were supported at the end of same brush to prepare bimodal polyethylene.The results showed that the activity of catalysts and the molecular weight of polyethylene are related to the steric hindrance of the R2 group of the phenoxyimine ligand. The activity of the supported catalyst is not lower than homogeneous catalyst, and the molecular weight of polyethylene decreased as the steric hindrance of R1 group of phenoxyimine ligand increased at high pressure (1MPa). The molecular weight of Ti-Cat-1 and Ti-Cat-3 appeared to decrease with increasing pressure. The molecular weight distribution of the mixed-ligand supported FI catalyst at low pressure is significantly broadened, and there is a tendency for bimodal polyethylene to appear. A special fish scale-like layer structure emerged by observing the polyethylene sample by SEM.In this paper, the FI catalysts was successfully loaded onto the brush-like topological supports, and the activity of the supported catalysts were greatly improved under the pressure of 1 MPa, which paved the way for the processing performance of polyethylene.

FI催化剂 催化剂负载 刷状载体 双峰聚乙烯

FI catalysts supported catalysts brush-like supporter bimodal polyethylene

中文

联合培养

南方科技大学

董振. 刷状载体负载FI催化剂制备双峰聚乙烯[D]. 深圳. 哈尔滨工业大学,2019.