Synthesis and characterization of well-defined optically active methacrylic diblock copolymers

A new, simple, and cost-effective approach toward the development of well-defined optically active diblock copolymers based on methacrylate monomers is described for the first time. Starting from the low-cost optically active (S)-(?)-2-methyl-1-butanol, a new optically active methacrylic monomer, namely, (S)-(+)-2-methyl-1-butyl methacrylate [(S)-(+)-MBuMA], was synthesized. Reversible addition fragmentation chain transfer polymerization was then used for preparing well-defined poly[(S)-(+)-MBuMA] homopolymers and water-soluble diblock copolymers based on [(S)-(+)-MBuMA] and the hydrophilic and ionizable monomer 2-(dimethyl amino)ethyl methacrylate (DMAEMA). The respective homopolymers and diblock copolymers were characterized in terms of their molecular weights, polydispersity indices, and compositions by size exclusion chromatography and 1H NMR spectroscopy. Polarimetry measurements were used to determine the specific optical rotations of these systems. The structural and compositional characteristics of micellar nanostructures possessing an optically active core generated by p((S)-(+)-MBuMA)-b-p(DMAEMA) chains characterized by predetermined molecular characteristics may be easily tuned to match biological constructs. Consequently, the aggregation behavior of the p[(S)-(+)-MBuMA]-b-p[DMAEMA] diblock copolymers was investigated in aqueous media by means of dynamic light scattering and atomic force microscopy, which revealed the formation of micelles in neutral and acidified aqueous solutions.