This paper discusses the synthesis of linear polyolefin elastomers containing divinylbenzene (DVB... more This paper discusses the synthesis of linear polyolefin elastomers containing divinylbenzene (DVB) units, including poly(ethylene-ter-propylene-ter-divinylbenzene) (EP-DVB) and poly(ethylene-ter-1-octene-ter-divinylbenzene) (EO-VDB). Several metallocene catalysts were evaluated to identify a system that can carry out monoenchainment of DVB and produce terpolymer with uniform molecular structure. Some resulting EP-DVB and EO-DVB terpolymers prepared by a rac-Et(Ind)2ZrCl2/MAO catalyst show good solubility in common organic solvents, controllable DVB content, high molecular weight, and narrow molecular weight and composition distributions. The uniform terpolymer microstructure also exhibits a DSC curve with a sharp glass transition temperature (Tg) that corresponds to its composition. Some EP-DVB and EO-DVB terpolymers with DVB content <2 mol % show low Tg's, below −45 and −55 °C, respectively. In turn, the pendent styrene moieties in the terpolymers are very versatile and engage in facile thermal and UV cr...
This paper discusses a direct (one-pot) polymerization process to prepare isotactic polypropylene... more This paper discusses a direct (one-pot) polymerization process to prepare isotactic polypropylene (i-PP) having a terminal functional group including Cl, OH, and NH2. The chemistry involves metallocene-mediated propylene polymerization using rac-Me2Si[2-Me-4-Ph(Ind)]2ZrCl2/MAO complex in the presence of styrene derivatives (St−f), carrying a Cl (St−Cl) or a silane-protected OH (St−OSi) or a silane-protected NH2 (St−NSi2), followed by hydrogenation. Apparently, the propylene propagating chain end engages in a facile consecutive chain transfer reaction, reacting with St−f and then hydrogen, with high catalyst reactivity under the proper St−f and hydrogen concentrations. The polymer molecular weight was inversely proportional to the molar ratio of [St−f]/[propylene] with a chain transfer constant (ktr/kp) of 1/21 for St−Cl, 1/34 for St−NSi2, and 1/48 for St−OSi, respectively. Both silane protecting groups were hydrolyzed in acidic aqueous solution during the sample workup step to obtain the desirable i-PP po...
This paper discusses the synthesis of linear polyolefin elastomers containing divinylbenzene (DVB... more This paper discusses the synthesis of linear polyolefin elastomers containing divinylbenzene (DVB) units, including poly(ethylene-ter-propylene-ter-divinylbenzene) (EP-DVB) and poly(ethylene-ter-1-octene-ter-divinylbenzene) (EO-VDB). Several metallocene catalysts were evaluated to identify a system that can carry out monoenchainment of DVB and produce terpolymer with uniform molecular structure. Some resulting EP-DVB and EO-DVB terpolymers prepared by a rac-Et(Ind)2ZrCl2/MAO catalyst show good solubility in common organic solvents, controllable DVB content, high molecular weight, and narrow molecular weight and composition distributions. The uniform terpolymer microstructure also exhibits a DSC curve with a sharp glass transition temperature (Tg) that corresponds to its composition. Some EP-DVB and EO-DVB terpolymers with DVB content <2 mol % show low Tg's, below −45 and −55 °C, respectively. In turn, the pendent styrene moieties in the terpolymers are very versatile and engage in facile thermal and UV cr...
This paper discusses a direct (one-pot) polymerization process to prepare isotactic polypropylene... more This paper discusses a direct (one-pot) polymerization process to prepare isotactic polypropylene (i-PP) having a terminal functional group including Cl, OH, and NH2. The chemistry involves metallocene-mediated propylene polymerization using rac-Me2Si[2-Me-4-Ph(Ind)]2ZrCl2/MAO complex in the presence of styrene derivatives (St−f), carrying a Cl (St−Cl) or a silane-protected OH (St−OSi) or a silane-protected NH2 (St−NSi2), followed by hydrogenation. Apparently, the propylene propagating chain end engages in a facile consecutive chain transfer reaction, reacting with St−f and then hydrogen, with high catalyst reactivity under the proper St−f and hydrogen concentrations. The polymer molecular weight was inversely proportional to the molar ratio of [St−f]/[propylene] with a chain transfer constant (ktr/kp) of 1/21 for St−Cl, 1/34 for St−NSi2, and 1/48 for St−OSi, respectively. Both silane protecting groups were hydrolyzed in acidic aqueous solution during the sample workup step to obtain the desirable i-PP po...
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Papers by Jingyan Dong