Novel thermoplastic elastomers: Star-blocks consisting of eight poly(styrene-b-isobutylene) arms radiating from a calix[8]arene core

The first synthesis by a core-first strategy of novel star-block copolymers consisting of eight poly(styrene-b-isobutylene); (PSt-b-PIB) arms radiatin g from a calix[8]arene core is described. An octafunctional methoxy calix[8 ]arene derivative was used to initiate the living polymerization of isobuty lene (IB) to desirable molecular weights, then styrene (St) was added to ob tain the sought star-blocks. Molecular weights and PSt contents were determ ined by triple-detector GPC and IH NMR spectroscopy. Star-black thermoplast ic elastomers containing 17-32% PSt showed high strength and elongation (up to similar to 26 MPa and >500%) and relatively low melt viscosities. The m echanical and rheological properties of these star-blocks are superior to t hose of linear PSt-v-PIB-b-PSt triblocks. PIE-based thermoplastic elastomer s may be of use as novel biomaterials.