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Asymmetric anionic polymerization of 2,7‐bis(4‐ t ‐butylphenyl)fluoren‐9‐ylmethyl methacrylate and photoinduced structural transition of the obtained polymer
Author(s) -
Watanabe Kento,
Sakamoto Takeshi,
Nakano Tamaki
Publication year - 2011
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/chir.20953
Subject(s) - polymerization , chemistry , monomer , polymer chemistry , polymer , chirality (physics) , circular dichroism , methacrylate , copolymer , photochemistry , crystallography , organic chemistry , chiral symmetry breaking , physics , quantum mechanics , nambu–jona lasinio model , quark
2,7‐Bis(4‐ t ‐butylphenyl)fluoren‐9‐ylmethyl methacrylate (BBPFMMA) was synthesized as a new candidate of a bulky monomer suitable for asymmetric anionic polymerization (IUPAC nomenclature: asymmetric helix‐chirogenic polymerization ) leading to a preferred‐handed helical, optically active polymer. The new monomer was polymerized using the complex of 9‐fluorenyllithium and (S) ‐(+)‐1‐(2‐pyrrolidinylmethyl)pyrrolidine in toluene at −78°C. As opposed to the original intention to obtain a polymethacrylate, the monomer seemed to undergo structural transition (decomposition) giving 2,7‐bis(4‐ t ‐butylphenyl)dibenzofulvene and the obtained polymer was most probably a terpolymer of BBPFMMA, 2,7‐bis(4‐ t ‐butylphenyl)dibenzofulvene, and methacrylic acid. The obtained polymer showed circular dichroism (CD) spectra, indicating that chirality had been introduced to the copolymer chain during the course of polymerization . On photo irradiation, the polymer underwent a structural transition involving a remarkable decrease in apparent molecular weight measured by size‐exclusion chromatography (SEC) and changes in FT‐IR spectral patterns. However, the CD spectrum of the polymer was not obviously altered by irradiation, indicating that polymer chirality is not affected by light. Chirality, 2011. © 2011 Wiley Periodicals, Inc.