Journal of Polymer Science Part A: Polymer Chemistry, Vol.55, No.23, 3918-3934, 2017
Ethylene/POSS Copolymerization Behavior of Postmetallocene Catalysts and Copolymer Characteristics
Copolymerization of ethylene with iso-butyl substituted monoalkenyl(siloxy)-or monoalkenylsilsesquioxane (POSS) comonomers over bis(phenoxy-imine) and salen-type titanium and zirconium catalysts was studied. It was found that the polyreaction performance was significantly depended by the kind of the catalyst and by the structure and concentration of POSS in the feed. The POSS comonomer was efficiently incorporated into the polymer chain at up to 0.2 mol %. The differences in the copolymer compositions as the functions of the catalyst kind and the POSS comonomer were observed, including the varied number-average sequence length of ethylene and unsaturated end groups, as determined by H-1 NMR and FT-IR. The presence of POSS comonomers affected also the melting and crystallization behavior of the copolymers, as evidenced by DSC, because of influence on the polymer chain arrangement. The POSS units could act as the nucleating agents. Moreover, the crystal and structural parameters of ethylene/POSS copolymers were evaluated on the basis of X-ray results, and the limited self-aggregation of POSS incorporated into the polymer chain, the small number and size of POSS aggregates, and the increased crystallinity degree of copolymers were demonstrated. The ethylene/POSS copolymers produced by postmetallocenes offered also high thermal stability and interesting morphological properties. (C) 2017 Wiley Periodicals, Inc.