Bhattacharyya Arpan, Sanyal Milan K, Mogera Umesha, George Subi J, Mukhopadhyay Mrinmay K, Maiti Santanu, Kulkarni Giridhar U
Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata, 700 064, India.
Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore, 560064, India.
Sci Rep. 2017 Mar 21;7(1):246. doi: 10.1038/s41598-017-00309-2.
Self assembled nanofibers derived from donor-acceptor (D-A) pair of dodecyl methyl viologen (DMV) and potassium salt of coronene tetracarboxylate (CS) is an excellent material for the development of organic electronic devices particularly for ultrafast response to relative humidity (RH). Here we have presented the results of in-situ grazing incidence small angle x-ray scattering (GISAXS) measurements to understand aridity dependent self reorganization of the nanofibers. The instantaneous changes in the organization of the nanofibers was monitored with different equilibrium RH conditions. Additionally formation of nanofibers during drying was studied by GISAXS technique - the results show two distinct stages of structural arrangements, first the formation of a lamellar mesophase and then, the evolution of a distorted hexagonal lattice. The RH dependent GISAXS results revealed a high degree of swelling in the lattice of the micelles and reduction in the distortion of the hexagonal structure with increase in RH. In high RH condition, the nanofibers show elliptical distortion but could not break into lamellar phase as observed during formation through drying. This observed structural deformation gives insight into nanoscopic structural changes of the micelles with change in RH around it and in turn explains ultrafast sensitivity in its conductivity for RH variation.
由十二烷基甲基紫精（DMV）和蒄四羧酸钾盐（CS）的供体-受体（D-A）对自组装而成的纳米纤维是开发有机电子器件的优良材料，尤其对相对湿度（RH）具有超快响应。在此，我们展示了原位掠入射小角X射线散射（GISAXS）测量结果，以了解纳米纤维与干燥度相关的自重组。在不同的平衡相对湿度条件下监测纳米纤维组织的瞬时变化。此外，通过GISAXS技术研究了干燥过程中纳米纤维的形成——结果显示出两个不同的结构排列阶段，首先是层状中间相的形成，然后是扭曲六方晶格的演化。与相对湿度相关的GISAXS结果表明，随着相对湿度的增加，胶束晶格出现高度膨胀，六方结构的扭曲程度降低。在高相对湿度条件下，纳米纤维呈现椭圆形扭曲，但不会像干燥过程中形成时那样分解成层状相。观察到的这种结构变形揭示了胶束的纳米级结构变化及其周围相对湿度的变化，进而解释了其电导率对相对湿度变化的超快敏感性。
