Thermoplastic elastomers based on polyisoprene, polybutadiene, or polybutylacrylate soft blocks and polymethylmethacrylate or polystyrene hard blocks have been synthesized previously by anionic and living radical polymerizations. This work reports the first synthesis of new thermoplastic elastomers based on polybenzofulvene (PBF) and polyisoprene (PI). In developing these new elastomers, well-defined homopolymers and block copolymers containing PBF blocks were synthesized by living anionic polymerization in benzene at room temperature via high vacuum techniques. NMR Analysis of homo-PBF microstructure indicated there there is 91% 1,4-addition and 9% 1,2-addition, withno 3,4 addition. PI-b-PBF block copolymers were synthesized by sequential anionic polymerization in a quantitative yield with narrow molecular weight distribution (Mw/Mn=1.12). Isoprene cannot be initiated by living polybenzofulvenyl lithium because of its low nucleophilicity. PBF-b-PI-b-PBF triblock copolymer was synthesized using a difunctional lithium-based initiator (1,3-phenylene)-bis-(3-methyl-1-phenylpentylidene), with lithium sec-butoxide as a polar additive in benzene. The pendent vinyl groups of the PI block were hydrosilylized using chlorodimethylsilane in order to attach chlorosilane groups along the backbone. Grafted triblock copolymer PBF-b-(PI-g-PBF)-b-PBF was synthesized by the reaction of living polybenzofulvene with chlorosilane groups on the PI block (Figure 1).                                                                           

Synthesis and characterization of new thermoplastic elastomers based on polybenzofulvene

248th National Meeting (2014)

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