| 초록 |
Two representative bulk polymers, polyolefin (PO) and polystyrene (PS), were molecularly connected to form PO-block-PS by sequentially performing coordination and anionic polymerizations in one pot. Ethylene/1-octene copolymerization was performed using a typical ansa-metallocene catalyst, rac-[Me2Si(2-methylindenyl)]2ZrCl2, in the presence of (benzyl)2zinc to grow PO-chains at the Zn site. Anionic styrene polymerization was subsequently performed using nBuLi·(tmeda) (tmeda, N,N,N',N'-tetramethylethylenediamine) initiator to consecutively grow PS-chains at the Zn site. The composition and the molecular weight of the PO-blocks were controllable depending on the feed amounts of 1-octene and (benzyl)2zinc (1-octene fraction: ~20, ~40 wt%; PO-Mw, 77,000–174,000) and the PS-block size was also controlled (PS-Mn, ~21,000) with the complete conversion of the styrene monomer. Formation of block copolymers was evident in the GPC curves, TEM images, and strain-stress curves. |
