Structure−Activity Relationship of New Nonlinear Optical Organic Materials Based on Push−Pull Azo Dyes. 3. Guest−Host Systems

Abstract

Several new push−pull azobenzene dyes with different electron-withdrawing groups, steric hindrance, and hydrogen-bonding capabilities were dispersed in poly(N-methacryloyl-N‘-phenylpiperazine), a glassy polymer matrix. After orientation by corona poling, the second harmonic generation (SHG) signals of the guest−host systems were measured as a function of time and temperature and fitted with Kohlrausch−Williams−Watts (KWW) stretched exponentials. The variations of their nonlinear susceptibilities at time zero and in their relaxation behavior were correlated with the changes of the chromophore chemical structure. Rigid rod structures always presented the best orientability and stability of the nonlinear optical properties.

Nonlinear optical properties of some side chain copolymers based on benzoxazole containing chromophores

“…22 The latter values are shown in Table III. Only for samples PId and PIIId good short term persistence of the SHG was obtained, while in the other cases stronger randomization processes did not allow a good stability of the NLO signal.…”

Synthesis and nonlinear optical properties of side chain liquid crystalline polymers containing azobenzene push–pull chromophores

“…It has been previously reported that N ‐methacryloyl‐ N ′‐phenylpiperazine and N ′‐phenylazophenyl derivatives are not prone to polymerize by a free radical polymerization 17. The steric hindrance of the N,N ‐dialkylmethacrylamide group was claimed as the reason for this failure of the polymerization.…”

Synthesis and structural characterizations of [chromophore]+‐saponite/polyurethane nanocomposites

“…Good thermal stability of the synthesized PU made it suitable to be used as the polymer matrix for NLO chromophores. However, the T g of the guest–host NLO polymer decreases as the chromophore content increases 35, 36. This implies that a plasticizing effect was present in the NLO‐active guest–host polymer.…”