Molecular Level Ordering of Poly(4-(4-vinylphenylpyridine)) and Dicarboxylic Acids by Hydrogen Bonding

Abstract

In this study, supramolecular aggregates ordered at a molecular-level were prepared by hydrogen-bonded self-assembly of poly(4-(4-vinylphenylpyridine)) (P4VPPy) and 1,1´-ferrocene dicarboxylic acid (FDA) in a polar solvent. Anionic polymerization of the monomer 4-(4vinylphenylpyridine) (4VPPy) synthesized via Suzuki coupling reaction led to the amorphous polymer P4VPPy with controlled molecular weight. Co-dissolving P4VPPy and FDA in DMSO resulted in hydrogen bond formation between pyridine groups and carboxylic acid groups. This was confirmed by Fourier-Transform Infrared spectroscopy(FT-IR) and X-ray Photoelectron Spectroscopy(XPS). The crystalline morphology of resulting thin films were investigated by High Voltage Electron Microscope(HVEM) coupled with X-ray Diffraction(XRD). The comprehensive analyses of the ordered patterns in HRTEM, FFT images and the crystalline patterns in XRD spectra reveal that hydrogen bonding assisted self-assembly of P4VPPy and FDA results in precise arrangements of the polymer chains and FDA molecules leading to a highly ordered material with face-centered cubic (FCC) crystal structure. Furthermore, 2,6-naphthalenedicarboxylic acid (NTDA), 1,4-benzenedicarboxylic acid (BZDA) and 1,2-ethanedicarboxylic acid (EDA) were also used in this study to investigate the effects of dicarboxylic acids in the ordering of materials.