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Methacrylic polymers containing permanent dipole azobenzene chromophores spaced from the main chain: synthesis and characterization
Author(s) -
Altomare Angelina,
Andruzzi Luisa,
Ciardelli Francesco,
Gallot Bernard,
Solaro Roberto
Publication year - 1998
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/(sici)1097-0126(199812)47:4<419::aid-pi78>3.0.co;2-m
Subject(s) - azobenzene , methacrylate , monomer , photochromism , polymer chemistry , materials science , chromophore , polymer , glass transition , photopolymer , moiety , thermotropic crystal , methacrylic acid , radical polymerization , photochemistry , chemistry , organic chemistry , composite material , liquid crystalline
Three photochromic monomers containing a permanent dipolephotochromic azobenzene group separated from the methacryloyl moietyby a polymethylene spacer, namely4‐(4‐oxy‐4′‐cyanoazobenzene)but‐1‐ylmethacrylate,6‐(4‐oxy‐4′‐cyanoazobenzene)hex‐1‐ylmethacrylate, and8‐(4‐oxy‐4′‐cyanoazobenzene)oct‐1‐ylmethacrylate, were synthesized in three steps starting from4‐cyanoaniline. These monomers were homopolymerized andcopolymerized with an optically active monomer,(−)‐menthyl methacrylate, in the presence ofAIBN as a radical initiator. The polymeric materials, having a molarcontent of photochromic units comprised between 5 and 100% andmolecular weights of about 15000, were characterized by an almostrandom distribution of monomeric units and a glass transitiontemperature ranging from 35 to 131°C. Polymer samples having acontent of aromatic units larger than 75% were characterized bya thermotropic liquid crystalline structure, as evidenced by opticalmicroscopy, X‐ray diffraction and DSC measurements.Two‐dimensional correlations spectroscopy (COSY)allowed an appreciable contribution by intramolecular charge transfermesomers to the electronic distribution of the azobenzene chromophoreto be highlighted. © 1998 Society of Chemical Industry