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Nucleobase‐Mediated Stereospecific Radical Polymerization and Combination with RAFT Polymerization for Simultaneous Control of Molecular Weight and Tacticity
Author(s) -
Tao Youhua,
Satoh Kotaro,
Kamigaito Masami
Publication year - 2011
Publication title -
macromolecular rapid communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 154
eISSN - 1521-3927
pISSN - 1022-1336
DOI - 10.1002/marc.201000614
Subject(s) - polymerization , tacticity , reversible addition−fragmentation chain transfer polymerization , polymer chemistry , monomer , radical polymerization , polymer , chemistry , chain growth polymerization , thymine , living polymerization , chain transfer , materials science , organic chemistry , dna , biochemistry
A highly soluble thymine‐based compound (1‐octyl thymine), having an array of hydrogen bonding sites with an ADA sequence (A and D: proton acceptor and donor sites, respectively), was used to mediate the stereospecific radical polymerization of an acrylamide monomer [ N ‐(6‐acetamidopyridin‐2‐yl)acrylamide] possessing the complementary DAD sequence. The thymine derivative interacted with the monomer via the selective 1:1 and strong triple hydrogen‐bonding interaction ( K = 1.1 × 10 3 in CHCl 3 at 20 °C) and mediated the syndiospecific radical polymerization of the monomer to give syndiotactic rich polymers up to r = 84% in CH 2 Cl 2 at −78 °C. A combination with the RAFT polymerization enabled simultaneous control of the molecular weight ( $\overline {M} _{{\rm w}} /\overline {M} _{{\rm n}} $ ≈ 1.5) and tacticity ( r = 73% and 76% at 60 and 20 °C, respectively) of the resulting polymers. Furthermore, the stereoblock polymerization was achieved upon the addition of the thymine‐based mediator during the RAFT polymerization to give the atactic‐syndiotactic stereoblock polymers with controlled molecular weights.