Study on side-chain second-order nonlinear optical polyimides based on novel chromophore-containing diamines. I. Synthesis and characterization

The facile synthesis and optical nonlinearity of hyperbranched polyaspartimides with azobenzene dyes

“…The longer conjugate length structure with higher rigidity would possibly hinder the close packing of polymer chains. This results in a decrease in intermolecular interactions [51]. According to the literature [52,53], the T g of a polarly functionalized cascade branched polymer mainly depends on the interactions of the end groups.…”

Study on side‐chain second‐order nonlinear optical polyimides based on novel chromophore‐containing diamines. II. Copolyimides possessing direct photolithographic features

“…For all PIs, no obvious absorption peak of the chromophore at about 370 nm was observed, and the cutoff wavelength of the absorption was below 440 nm. The following was one of the advantages of those PIs containing this kind of triazine containing chromophores:38 They all possessed high transparency especially at the possible operating wavelengths of electro‐optic devices.…”

“…Benzophenone‐3,3′,4,4′‐tetracarboxylic dianhydride (BTDA) was prepared from benzophenone‐3,3′,4,4′‐tetracarboxylic acid (industrial product, purchased from Beijing Tar Chemical Co., Beijing, China) by refluxing with an excessive amount of acetic dianhydride for 2 h. 4,4′‐Diamino‐3,3′‐dimethyldiphenylmethane (MMDA) and 4‐nitro‐4′‐[ N ‐(4,6‐di‐4‐aminophenylamino)‐1,3,5‐triazin‐2‐yl]aminoazobenzene (M4) were synthesized in our laboratory and previously reported 37, 38 . N ‐methyl‐2‐pyrrolidone (NMP) and isopropanol (both analytical reagent grade, purchased from Shanghai Reagent Co., Shanghai, China) were dried over molecular sieves before use.…”

Nonlinear optical polyimide/montmorillonite nanocomposites consisting of azobenzene dyes

“…The T d of the polyimide was observed at 373.6 C. In addition, the T g of the polyimide functionalized with DO3 (PIDO3) was observed at 165.3 C, whereas the T d was observed at 240.9 C. As the dyes were covalently attached to the side chain of polyimide, the T g of the polymer decreased significantly. This might be due to the fact that the side-chain dyes prevented tight packing between polymer chains, leading to a decrease in intermolecular interactions [37]. Fig.…”