The Phillips catalyst comprising Cr active species and silica support is responsible for the commercial production of high-density polyethylene (HDPE). However, the active-site structure and its relationship with polymer properties are still unclear, because of a great extent of surface heterogeneity. Polyhedral oligomeric silsequioxane (POSS) is regarded as a model silica, which can represent different surface silanol groups by various POSS cages and hydroxyl groups. In this study, we synthesized homogeneous Phillips catalysts using POSS. Catalyst characterization indicated that the Cr(III) precursor was reacted with two hydroxyl groups to bear (Me
3Si)
2CH-Cr(-O-Si-)
2 structures for both catalysts, remained one hydroxyl group in Cr(III)/POSS-3OH.
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