Functionalized Phenoxy-Imine Catalyst for Synthesizing Highly Crystalline Nascent UHMWPEs. 1. Molecular Weight Characteristics and Polymer Morphologies

Abstract

Based on the established achievements, a novel phenoxy-imine catalyst [2-C(CH3)3-4-(OCH2CH=CH2)-6-(2,3,4,5,6-C6F5-N=CH)C6H3O)]2TiCl2 was synthesized by introducing both tert-butyl and alloxy substituents to the ligand skeleton. The catalyst demonstrates an extremely high activity towards ethylene polymerization, and gives access to UHMWPE with adjustable molecular weight just by changing either reaction time or temperature. In order to acquire molecular weight characteristics on multiple levels, a hyphenated HTSEC-LALS-RI-VIS triple detection array (HTSEC-TDA) technique has been applied. By coupling the three detectors, we obtain the averages and distributions of molecular weight, macromolecular size, conformation plots and Mark-Houwink plots of the UHMWPEs. Through a detailed analysis, the nature of molecular weight characteristics and macromolecular structure of the UHMWPEs are disclosed. Further characterized by DSC and SEM, the polymer morphologies for the nascent UHMWPEs will be clarified thereinafter.