High Molecular Orientation in Mono- and Trilayer Polydiacetylene Films Imaged by Atomic Force Microscopy

Template Growth of Nanocrystalline PbS, CdS, and ZnS on a Polydiacetylene Langmuir Film: An In Situ Grazing Incidence X‐ray Diffraction Study

“…These unique templates are attractive for the growth of ordered inorganic nanocrystalline materials at the air/solution interface because of their amphiphilic nature, chemical and mechanical stability, structural anisotropy, and unique optical and electrical properties. [4][5][6][7] Various techniques were used to determine the 2D crystal structure of PDA, including electron diffraction (ED) carried out in a transmission electron microscope, [8,9] atomic force microscopy (AFM), [10] Fourier transform IR (FTIR) spectroscopy [11] and synchrotron grazing incidence X-ray diffraction (GIXD). [12,13] It was found that PDA can exist in two chromatic phases, whose ordered crystalline parts differ by the packing of the amphiphilic tails, while the conjugated backbone spacing remains nearly constant for both structures (ca.…”

Material Anisotropy Revealed by Phase Contrast in Intermittent Contact Atomic Force Microscopy

“…PDA monolayer films were prepared on a mica substrate using a Langmuir deposition technique [12]. PDA monolayers exhibit strong anisotropy that is correlated with their aligned polymer backbone structure [ Fig.…”

“…1(a) inset] [12][13][14][15]. For example, friction measured with LFM is 3 times larger when sliding perpendicular vs parallel to these backbones [12][13][14][15], which is likely due to anisotropy in the monolayer's inelastic shear deformation modes [13].…”

“…Islands of multilayer PDA are also visible. The monolayer regions are polycrystalline, and each domain can be identified by the orientation of the striations visible in the phase image along which the PDA backbones lie [12,17]. The typical phase f in Fig.…”

Directional shear force microscopy

“…We use a Langmuir-Blodgett monolayer of the conjugated polymer polydiacetylene ͑PDA͒ that has been transferred to an atomically flat SiO 2 substrate. 15 AFM measurements showed that the PDA exhibits friction anisotropy that correlates with the direction of its polymer backbones that run parallel to the surface in domains ͑Ͼ100 m 2 ͒ with different in-plane orientations. 4 Details concerning the structure of these films are reported elsewhere, 4,15 but for the present purpose we note that the AFM friction force is highest ͑lowest͒ when scanning perpendicular ͑parallel͒ to the FIG.…”