In this work, ethylene/1‐hexene copolymerization with a novel SiO2‐supported inorganic and organic hybrid chromium‐based catalyst was investigated. This catalyst was prepared using the residual surface hydroxyl groups in Phillips catalyst to support bis(triphenylsilyl) chromate (BC) in order to get the merits from two important chromium‐based catalysts namely inorganic Phillips and organic S‐2 catalysts. The influences of addition amount of 1‐hexene and BC were systematically investigated. With increasing 1‐hexene from 0 to 7 vol%, the activity of HCat‐2 catalyst showed a decreasing tendency. Its copolymer also showed the better short chain branches distribution through the temperature rising elution fractionation cross successive self‐nucleation and annealing characterization.
Industrial ethylene‐hexene copolymer samples produced using a supported Ti‐based Ziegler‐Natta catalyst were deconvoluted into five Flory molecular weight distributions (MWDs). Relationships between reactor operating conditions and deconvolution parameters confirmed that temperature and hydrogen and hexene concentrations influenced the MWD. The two sites that produced low‐molecular‐weight polymer responded similarly to changes in reactor operating conditions, as did the three sites that produce high‐molecular‐weight polymer. Increasing hexene concentration resulted in relatively more polymer being produced at the two low‐molecular‐weight sites and less at the high‐molecular‐weight sites. The information obtained will be useful for making simplifying assumptions during kinetic model development.
Comb‐shaped glycopolymer/peptide bioconjugates are constructed by grafting reduced glutathione (GSH) onto acrylate‐functional block glycocopolymers via thiol‐ene click chemistry. In aqueous solution, the glycopolymer/GSH bioconjugate self‐assembles to sugar‐installed spherical micelles. The size of micelles decreases with increasing pH, demonstrating pH‐responsive character. The isoelectric point (IEP) of the PMAGlc/GSH bioconjugate is estimated to be 3.43. The micelles show a specific interaction with the protein Concanavalin A. At endosomal pH, the PMAGlc/GSH bioconjugate can gradually degrade. These pH‐responsive glycopolymer/peptide micelles with biological recognition and degradation can be used as multifunctional nanocarriers for targeted drug delivery.
