Solid-state Structure and Formation of Organized Molecular Films for Poly-(N-alkylated benzamides) Containing Various Chain Lengths

We investigated the solid-state structure and formation of organized molecular films for newly synthesized aromatic polyamides having both a rigid main-chain and a flexible side-chain with different lengths by wide angle X-ray diffraction (WAXD), small-angle X-ray scattering (SAXS), and surface pressure-area (π–A) isotherm measurements. The solid-state structure of poly-(N-methylbenzamide) (PABA1) belonged to the monoclinic system, whereas PABA3, PABA4, and PABA5 showed an orthorhombic packing system. PABA7 and PABA8 formed amorphous polymers. In the case of PABA17, a two-dimensional hexagonal lattice was formed as a sub-cell consisting of side chains. These polymer monolayers were highly condensed on a water surface at 15 °C. From these experimental findings, it is concluded that the polymer synthesis method employed in this study can be directly used to control the crystalline morphology (the third order structure of polymers) of polymer monolayers.