Olefinic thermoplastic elastomers has broad hardness range, high flexibility, low density, and excellent recyclability. However, they are limited in applications due to their low elasticity and low operating temperature. To overcome these problems, olefin/α-olefin copolymers have been developed.
In this study, polyolefin-g-poly(t-butylstyrene) as one of the high-temperature polyolefin-based thermoplastic elastomers was synthesized by the graft-from anionic living polymerization from the styrene moieties of the linear poly(ethylene-ter-1-hexene-ter-divinylbenzene)(PEHV) and toluene moieties of the linear poly(ethylene-ter-1-decene-ter
-p-methylstyrene)(PEDM) as the soft block to form the hard end blocks, poly(t-butylstyrene). Prior to the experiment, PEHV terpolymers and PEDM were prepared by a metallocene copolymerization using rac-Et(Ind)2ZrCl2/MAO catalyst system. The chemistry of the anionic graft-from polymerization involved lithiation of the pendant styrene unit of the soft polyolefin elastomer by sec-BuLi/TMEDA followed the subsequent graft anionic polymerization of tert-butylstyrene. After grafting-from polymerization of t-butylstyrene, all vinyl units of the styrene-pendent elastic polyolefin was totally disappeared which was the confirmation of high grafting efficiency. Poly(t-BS) hard graft size (Mn=2,000~40,000 g/mol) was controlled by the DVB molar ratio.
In order to observe the physical properties and heat resistance, the investigation of phase separation phenomenon could be conducted by mechanical properties and dynamic mechanical properties analysis with various poly(t-BS) graft size. Consequently, The phase separation phenomenon appeared while the poly (t-BS) hard graft size is 5,000 g / mol or more. Mechanical properties would be significantly changed by various hard block content(15 ~ 40wt%) and graft size.

The synthetic methodology for the multi-functional chain-end modified polyolefin-g-poly(t-BS) was proposed via the thiol-ene click reaction by thermal and photo-chemical methods using 2-mercaptoethanol and thiolglycolic acid as the functional agent after the synthesis of polyolefin-g-[poly(t-BS)-b-high vinyl PI], which was obtained from the subsequent living block copolymerization using polyolefin-g-poly(t-BS) with high vinyl-polyisoprene.
The result indicated that this process produced a new well-defined functionalized graft-type polyolefin-based TPE with high Tg hard block(> 145 ℃).