Synthesis and electro‐optical properties of novel Y‐type polyurethanes containing dioxynitrostilbene

Abstract

3,4-Di-(2 -hydroxyethoxy)-4 -nitrostilbene (2) was prepared by the reaction of 2-iodoethanol with 3,4-dihydroxy-4 -nitrostilbene. Diol 2 was condensed with 2,4-toluenediisocyanate, 3,3 -dimethoxy-4,4 -biphenylenediisocyanate and 1,6-hexamethylenediisocyanate to yield novel Y-type polyurethanes 3-5 containing dioxynitrostilbene as a non-linear optical (NLO)-chromophore. Polymers 3-5 were soluble in common organic solvents, such as acetone and DMF. These polymers showed thermal stability up to 280 • C in TGA thermograms with T g values in the range of 100-143 • C in DSC thermograms. The approximate lengths of aligned NLO-chromophores of the polymers estimated from AFM images were around 2 nm. The SHG coefficients (d 33 ) of poled polymer films were around 4.5 × 10 −8 esu. Poled polymer films had improved temporal and long-term thermal stability owing to the hydrogen bonding of urethane linkage and the main-chain character of the polymer structure, which are acceptable for NLO device applications.

Molecular design, synthesis, and electro‐optic properties of novel Y‐type polyesters with high thermal stability of second harmonic generation

“…Thus, we obtained a new type of NLO polyester having the advantages of both main‐chain and side‐chain NLO polymers: stabilization of dipole alignment and good solubility. These polyesters exhibit good thermal and solubility properties as in the Y‐type polyurethanes24 and T‐type polyimides 25…”

Synthesis and electro‐optic properties of novel polyurethane containing the nitrophenylazoresorcinoxy group

“…Physically crosslinked systems via hydrogen bonds have advantages such as homogeneity and good processability relative to chemically crosslinked systems, which suffer from significant optical loss and poor solubility. Recently we prepared novel polyurethanes containing dioxynitrostilbene, and dioxybenzylidenemalononitrile as NLO chromophores , . The resulting polymers exhibit high thermal stability of second harmonic generation (SHG), which stems from the stabilization of dipole alignment of the NLO chromophore.…”

Preparation and electro‐optic properties of novel Y‐type polyimides with highly enhanced thermal stability of second harmonic generation

“…Main‐chain NLO polymers have good thermal stability of dipole alignments, but they often do not dissolve in organic solvents, and their intractability makes them unusable to fabricate stable noncentrosymmetric films. Recently we prepared novel Y‐type NLO polyurethanes and polyesters with enhanced thermal stability of second harmonic generation (SHG) 28, 29…”