Syndiospecific Coordination Polymerization of Si‐H‐Containing Styrenes Catalyzed by Scandium Complex and Synthesis of Styrene‐Based Triblock Copolymers

: The controlled syndiospecific polymerization of three Si-H-containing styrenes, that is, 4-(methylhydrosilyl)styrene (FSt-1), 4-(dimethylhydrosilyl)styrene (FSt-2) and 4-(diisopropylhydrosilyl)styrene (FSt-3), is realized in the presence of (C5 Me4 SiMe3 )Sc (CH2 C6 H5 )2 (THF)/[Ph3 C][B(C6 F5 )4 ]. Then a series of FSt-b-styrene-b-FSt triblock copolymers (FSt-St-FSt) are synthesized facilely via a sequential monomer feeding process (FSt-2, styrene, and FSt-2, respectively) during the polymerization. The syndiotactic polystyrene (sPS) block in the middle endows the copolymer with high melting point above 250 °C, whereas the Si-H groups on monomer FSt-2 introduce functional pendants to the end-blocks (with Si-H content of 31-63 mol%). Finally by a mild and high-effective hydrosilylation reaction, novel polar-group functionalized sPS is obtained.