Synthesis of ABA Triblock Copolymers via Acyclic Diene Metathesis Polymerization and Living Polymerization of α-Amino Acid−N-Carboxyanhydrides

The synthesis of poly(γ-benzyl- l -glutamate)- b -polyoctenamer- b -poly(γ-benzyl- l -glutamate) ( 13 ) and poly(γ-benzyl- l -glutamate)- b -polyethylene- b -poly(γ-benzyl- l -glutamate) ( 14 ) triblock copolymers is described. α,ω-Bisamino-terminated polyoctenamer ( 5 ) was used to prepare a difunctional macroinitiator ( 12 ) used for the living polymerization of γ-benzyl- l -glutamic acid− N -carboxyanhydride (Glu−NCA) to form the triblock copolymers. 5 was synthesized by acyclic diene metathesis polymerization of 1,9-decadiene ( 1 ) in the presence of 11-phthalimido-1-undecene ( 2 ) and Grubbs' metathesis catalyst, RuCl 2 ( CHPh)(PCy 3 ) 2 ( 3 ). Deprotection of the resulting phthalimide end-functionalized polymers ( 4 ) was performed, leading to difunctional 5 with number-average functionalities close to two. These methods allow the controlled preparation of polypeptide/(hydrocarbon polymer) block architectures with good control over the chain lengths of both domains and without formation of homopolypeptide contaminants.