| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2006: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 2005: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Research Abstract |
As a part of our continuous efforts to the development of highly ordered hierarchical structures from amino acid-based polymers and intelligent hybrid materials with characteristic stimuli-responsive properties, we conducted the synthesis of polyacrylamides having amino acid moieties by reversible addition-fragmentation chain transfer (RAFT) polymerization. Various acrylamides, such as N-acryloyl-L-phenylalanine methyl ester (A-Phe-OMe), N-acryloyl-L-phenylalanine (A-Phe-OH), and N-acryloyl-L-proline methyl ester (A-Pro-OMe), were selected as amino acid-containing monomers. The RAFT polymerization of these monomers using suitable chain transfer agents allowed the synthesis of well-defined amino acid-based polymers with pre-determined molecular weights, narrow molecular weight distributions, and characteristic stimuli-responsive properties.
Controlled radical polymerization of A-Phe-OH having the carboxylic acid moiety was attained via direct RAFT polymerization without protection chemis
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try. The resulting poly(A-Phe-OH) was a weak polyelectrolyte, in which the degree of ionization of carboxylic acids could be easily controlled by the pH value. Poly(A-Pro-OMe) and the random copolymers exhibited a characteristic Lower Critical Solution Temperature (LCST = 15-45 ℃) in aqueous solution. The RAFT polymerization procedure could be extended to the synthesis of well-defined block copolymers derived from various amino acids and controlled architectures. Characteristic chiroptical property, assembled structures, and thermally induced phase separation behavior of the block copolymers were evaluated using various methods. Since specific intra-and intermolecular interactions via hydrogen-bonding and ionic complexation, hydrophilicity/hydrophobicity, and chirality may be manipulated by the nature of the amino acid moieties, the self-organization of the well-defined polymers can provide a viable route to the production of tailored amino acid-based materials with unique intelligent properties for various applications. Less
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