Research on multilayer organic thin film gains much attention for its many applications like optoelectronics, purification membranes, sensor, fuel cell etc. One of the simple and versatile techniques to prepare multilayer thin film is solution based LBL deposition technique.1 In this research, we focus on the synthesis of variable densities polyurea multilayer thin film on solid surface by sequential dipping into the solution of bi-functional 1,3-Phenylene diisocyante (PDI) and tetra-functional Tetrakis (4-aminophenyl) methane (TAM) reactive moieties. (Layer-by-Layer) multilayer growth was inspected by UV-Vis absorption spectroscopy. The linear increase of absorption intensity with deposition cycles represents the multilayer deposition. Three characteristic infrared bands of amide I, amide II and asymmetric (N-C-N) stretching band, confirmed the formation polyurea networks. XPS studies also unveiled the formation of polyurea networks. The structural periodicity was measured with GI-SAXS technique. It was found that the structural periodicity enhanced along with layer growth at surface normal (qz) direction on substrate surface. This result indicates that a threshold thickness is required to get molecular ordering at surface normal direction. Film thickness and film mass density were measured by X-ray reflectivity (XRR). It revealed that film mass density increased significantly with layer growth. While, 10 cycles film exhibits linear mass density throughout the film. In contrast, 20 and 30 cycles deposition case, film extending away from substrate surface is ca. 16% more dense than film proximate to the surface (Figure 1). This variation of mass density can be explained by different degree of cross-linking phenomena among film proximate to the surface and extending away to the surface. References: (1) Lee, B. H.; Ryu, M. K.; Choi, S. Y.; Lee, K. H.; Im. S.; Sung, M. M. J. Am. Chem. Soc. 2007, 129, 16034.

Synthesis of multilayer organic thin film with variable densities by layer-by-layer (LBL) deposition technique

251st National Meeting (2016)

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