Stabilization of Amino Acid Derived Diblock Copolymer Micelles through Favorable D:L side chain interactions

Optically pure N-acryloyl-(D)-leucine methyl ester (D-Leu-OMe) (1) and N-acryloyl-(1)-leucine methyl ester (L-Leu-OMe) (2) were synthesized and studied using infrared spectroscopy and melting point analysis to determine if D-L interactions are preferential relative to D-D or L-L interactions. Reversible addition-fragmentation chain transfer (RAFT) polymerization yielded enantiopure homopolymers of D-Leu-OMe (1) and L-Leu-OMe ester (2). The two enantiopure polymers. 5 and 6. and a 1:1 w/w racemic blend of both polymers were studied using infrared spectroscopy to investigate the intermolecular interactions in the polymeric systems. Poly(tert-butyl acrylate) [P('BuA)] macro chain transfer agents were used to synthesize two diblock copolymers from 1 and 2. respectively. Subsequent deprotection of the P('BuA) block to poly(acrylic acid) (PAA) yielded two chiral amphiphilic diblock copolymers. 7 and 8. Both enantiopure polymers were self-assesmbled separately and then in a 1:1 w/w ratio, and the resulting morphologies characterized using dynamic light scattering, atomic force microscopy, transmission electron miroscopy, and circular dichroism.