All-acrylic multigraft copolymers composed of glassy poly(methyl methacrylate) side chains randomly attached to a rubbery poly(n-butyl acrylate) backbone were synthesized using a ‘grafting-through’ approach and characterized for their use as thermoplastic elastomers (TPEs). The synthetic procedure, which employed both anionic and reversible addition-fragmentation chain-transfer (RAFT) controlled radical polymerization techniques, produced high molecular weight (&gt;100 kg/mol) materials with both tunable volume fractions of each acrylic component and average number of branch point junctions per chain. The mechanical properties, investigated by rheology, dynamic mechanical analysis, and tensile testing, showed elongations at break to exceed 200% with the ability to increase the materials stiffness above 1.0 MPa. Additionally, anionic polymerization of benzofulvene with different initiation systems produced polybenzofulvene (PBF) with different glass transition temperatures. With sec-BuLi as the initiator and polymerized in benzene at room temperature, PBF had 22% of 1,2-microstructure with Tg of 145 oC. When n-BuLi was used as the initiator with 1,2-dimethoxyethane (DME) as the polar additive, resulting PBF contained virtually 99% of 1,2-microstructure with Tg of 190 oC. Macromonomers of PBF with tunable glass transition temperature could be prepared by using protected hydroxyl anionic initiator with different polar additives. By using similar RAFT or emulsion polymerization techniques with PBF macromonomer as the glass side chain and isoprene or n-butyl acrylate as the rubbery backbone, TPEs with tunable upper service temperature could potentially be prepared.

All-acrylic and tunable upper service temperature superelastomers synthesized using the grafting-through approach

251st National Meeting (2016)

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