Synthesis of Hydrophilic Thermoplastic Elastomer with Outstanding Mechanical Properties via the Copolymerization of Ethylene and Methoxystyrene

Polyolefin thermoplastic elastomers are of fundamental interest and practical importance. Herein, we report the copolymerization of ethylene (E) with three kinds of styrene derivatives (ortho-methoxystyrene (oMOS), meta-methoxystyrene (mMOS), and para-methoxystyrene (pMOS)) using two kinds of heterocyclic-fused cyclopentadienyl scandium complexes 1 and 2. E-oMOS copolymer products with glass-transition temperatures (Tg) higher than room temperature behave as hard plastics, while E-mMOS copolymers are thermoplastic elastomers with lower Tg values (−13 to −23 °C). E-mMOS copolymers have higher number-averaged molecular weight (Mn 4.7–11.6 g mol–1) and show excellent mechanical properties due to the unique multiblock-like chain structures composed of relatively long crystalline E–E segments as hard parts and short amorphous mMOS-mMOS sequences as soft parts. The chain and phase structures of E-mMOS copolymers have been studied by nuclear magnetic resonance (NMR) spectra, atomic force microscopy (AFM), and wide-angle X-ray diffraction (WAXD) analysis. Incorporation of mMOS groups endows materials with improved hydrophilic surface properties and high mechanical properties.