The role of intermolecular interactions in polyaniline/polyamide-6,6 pressure-sensitive blends studied by DFT and ^sup 1^H NMR

• Published in: European polymer journal Vol. 85; p. 588
• Main Authors: Lopes, Eluise S, Domingos, Eloílson, Neves, Rodrigo S, Romão, Wanderson, de Souza, Kátia R, Valaski, R, Archanjo, Braulio S, Souza Jr, Fernando G, Silva, Alexander M, Kuznetsov, Alexei, Araujo, Joyce R
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier BV 01-12-2016
• Subjects: Carbonyl groups; Carbonyls; Chains (polymeric); Composite materials; Conducting polymers; Conductivity; Density functional theory; Differential scanning calorimetry; Electrical resistivity; Enthalpy; Heat measurement; Mechanical analysis; Nitrogen atoms; NMR; Nuclear magnetic resonance; Polyanilines; Polymer blends; Polymer matrix composites; Polymers; Scanning electron microscopy; Sensitivity; Spectrum analysis; Thermal analysis
• ISSN: 0014-3057; 1873-1945

The aim of this work was to understand the electrical-mechanical response of polyaniline-thermoplastic blends measured under dynamic conditions and to evaluate the effectiveness of this conducting blend as a pressure sensor. The studied composite materials were based on conducting blends composed of polyaniline, as the conducting phase, dispersed into an insulating thermoplastic polymer, polyamide-6,6. The compression sensitivity (conductivity changes response) of these materials was investigated. The range of polyaniline content in the studied blends was from 50 to 92 wt.%, as estimated from melting enthalpies of temperature-modulated differential scanning calorimetry measurements. PA-6,6/PAni blend with 92 wt.% PAni showed the highest electrical conductivity (6 x 10-5 S cm-1) due to the presence of positively charged nitrogen atoms (N+) evidenced by XPS, as well as the highest compression sensitivity (25% MPa-1), attributed to the interconnected conducting network formed in PAni phase, as disclosed by SEM images. The first-principles calculations based on the density functional theory (DFT) were used to describe the interactions between NH-C=O and H-N-phenyl segments of the PA-6,6 and PAni chains, respectively. -1H Nuclear Magnetic Resonance spectra showed good agreement with the theoretical model through the observation of chemical shifts related to the chemical interaction between H from amine-N of PAni and carbonyl groups of PA-6,6.