超支化偶氮大分子重氮盐静电层-层自组装膜的制备及光响应性研究

利用超支化偶氮大分子重氮盐作为聚阳离子,与聚阴离子PSSA进行静电层-层自组装,通过紫外光谱、椭偏仪和原子力显微镜等对体系自组装过程及自组装膜的表面形貌进行了表征.在线偏振488nmAr+激光的作用下,自组装多层膜可产生明显的光致二向色性,其取向有序度约为0.02.在干涉的Ar+激光作用下,多层膜表面可形成规则的表面起伏光栅结构.

Fabrication of Photoresponsive Electrostatic Multilayers Containing Diazonium-Hyperbranched Azo Polymer

A novel hyperbranced azo polymer with terminal diazonium groups was synthesized by step-growth polymerization of 4,4'-diamino diphenyl sulphone's diazonium salts(A_2)and benzene-1,3,5-tricarboxylic acid tri-2-(N-ethylanilino)ethyl ester(B_3)through azo-coupling reaction.4,4'-diamino diphenyl sulphone(0.248 g,1 mmol)was dissolved in a hot homogeneous mixture of glacial acetic acid(7.5 mL)and sulfuric acid(1 mL).Aqueous solution of sodium nitrite(0.166 g,2.4 mmol)in 0.5 mL water was added dropwise into the solution at 0℃ and kept at this temperature for 5 min.The diazonium salt solution of 4,4'-diamino diphenyl sulphone was then added dropwise into the solution of benzene-1,3,5-tricarboxylic acid tri-2-(N-ethylanilino)ethyl ester(0.326 g,0.5 mmol)in 50 mL DMF at 0℃.After the reaction was carried out at 0℃ for 8 h,the solution containing the diazonium-hyperbranched azo polymer was directly used as the polycation solution.The purchased sodium polystrene sulfonate(PSSA)was used as polyanion.Then the multilayer films were prepared by an electrostatic layer-by-layer deposition method.The self-assembly processes and morphologies of surfaces were characterized by UV-Vis spectra,ellipsometer and AFM.A linear increase of absorbance and thickness was observed as the number of the bilayers increased.Dichroism was optically induced in the self-assembly film under the irradiation of a polarized Ar+ laser beam at 488 nm.After 15 min irradiation of the laser beam at an intensity of 80 mW/cm2,the orientation order parameter of the multilayer film obtained was about 0.02.With interfering illumination of Ar+ laser beams for 30 min,significant surface relief gratings formed on the self-assembly multilayer film were observed.The spatial period and height of the obtained SRGs were about 744 nm and 20 nm,respectively.