New Thermoplastic Elastomers by Quasiliving Atom Transfer Free Radical Grafting

Controlled synthesis of a new thermoplastic elastomer (TPE), poly(isobutylene-g-styrene) (PIB-g-PSt) was achieved by quasiliving atom transfer radical polymerization (ATRP). A new commercially available butyl rubber containing bromobenzyl moieties was used as macroinitiator for ATRP of styrene catalyzed by CuBr/2,20-bipyridine complex. Both bulk and solution polymerization resulted in well-defined graft copolymers as indicated by analyses with ¹ H NMR and GPC. Phase separated morphology in these graft copolymers was found by DSC. Stress-strain analyses indicate high elongation and tensile strength for PIB-g-PSt grafts with certain composition. This new grafting process and the resulting TPE are candidates for several useful applications.