CONTROLLED SYNTHESIS OF POLYACRYLAMIDES CONTAINING AMINO ACID MOIETIES VIA RAFT AND THEIR STUMULI-RESPONSIVE PROPERTIES

1However, there is still a large gap between the performance and architectures of most synthetic polymers and biologically produced polymers. The desirable requirement is to develop synthetic methods to control the sequence and composition of amino acids, chain chirality, conformation, amphiphilicity, and chain length. It is also important to produce polymers possessing narrow chain length distributions, which can assemble linear macromolecules into precisely defined nanostructures. We here report controlled synthesis of polyacrylamides having amino acid moieties in the side chains by reversible addition-fragmentation chain transfer (RAFT) polymerization. Three acrylamides, N-acryloyl-Lphenylalanine methyl ester (A-Phe-OMe), N-acryloyl-L-phenylalanine (APhe), and N-acryloyl-L-proline methyl ester (A-Pro-OMe), were selected as amino acid-containing monomers (Figure 1). The amino acid functionality and chirality in the well-defined polymer chains can enhance the potential to produce highly ordered hierarchical structures, such as α-helices and βsheets, scaling from a few nanometers to several microns. So-called “intelligent” or “smart” materials that can sense signals and produce a definite dynamic response in the form of a change in shape, size, or structure, is another central to developments in various scientific fields. The poly(A-Phe) obtained in this study is a week polyelectrolyte, in which the degree of ionization of carboxylic acids can be easily controlled by the pH value. While, poly(A-Pro-OMe) exhibits a characteristic LCST (Lower Critical Solution Temperature) in aqueous solution. Our attention was focused on amino-acid based polymers with not only well-defined architectures but also characteristic stimuli-responsive properties.