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Tailoring Linear and Nonlinear Optical Properties of a Side‐Chain Liquid Crystalline Azo‐Polymethacrylate
Author(s) -
Alicante Raquel,
Cases Rafael,
Villacampa Belén,
Oriol Luis
Publication year - 2010
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.201000238
Subject(s) - birefringence , materials science , irradiation , second harmonic generation , anisotropy , side chain , annealing (glass) , refractive index , homeotropic alignment , spectroscopy , optics , liquid crystal , polymer chemistry , polymer , optoelectronics , composite material , laser , physics , nuclear physics , quantum mechanics
The molecular orientation in a side‐chain liquid crystalline azopolymer with push–pull chromophores ( Pol‐PZ‐CN ) is studied by UV‐vis spectroscopy, refractive index and second harmonic generation measurements. Fresh films show homeotropic arrangement, but irradiation with polarized light induces “in‐plane” birefringence, which is enhanced by subsequent thermal annealing up to values as high as 0.34. The nonlinear response of Corona poled films with “in‐plane” anisotropy is governed by three independent NLO d ij coefficients, evidencing symmetry different from the usual ( C ∞v ). For irradiated films, stable values d 31 = 1.4, d 32 = 0.9 and d 33 = 11 pm·V −1 are measured at 1.9 µm. A noticeable higher d 31 / d 32 ratio is obtained for preirradiated and annealed films. The proposed two‐step method consisting of light irradiation and heating is an effective strategy to tailor the polar molecular orientation of nonlinear liquid crystalline azopolymers.