Insights into the Chain and Local Mobility of Some Aromatic Polyamides and Their Influence on the Physicochemical Properties

• Published in: Macromolecular chemistry and physics Vol. 215; no. 16; pp. 1573 - 1587
• Main Authors: Damaceanu, Mariana-Dana, Rusu, Radu-Dan, Cristea, Mariana, Musteata, Valentina-Elena, Bruma, Maria, Wolinska-Grabczyk, Aleksandra
• Format: Journal Article
• Language: English
• Published: Weinheim Blackwell Publishing Ltd 01.08.2014; Wiley; Wiley Subscription Services, Inc
• Subjects: Applied sciences; Aromatic polyamides; chain and local movement; Chain mobility; Correlation analysis; Dielectric relaxation; Electrical, magnetic and optical properties; Exact sciences and technology; Fluorination; gas permeability; Naphthalene; Organic polymers; Permeability; Physicochemistry of polymers; Polyamide resins; polyamides; Polymers; Properties and characterization; sub-glass relaxations; wetting properties; Transport properties; Nylon; wetting properties; Fluorine containing polymer; Aromatic polymer; Experimental study; Molecular relaxation; chain and local movement; Dielectric relaxation; Gas permeability; Wettability; polyamides; sub-glass relaxations; Surface properties; Selective permeability; Activation energy; Comparative study
• ISSN: 1022-1352; 1521-3935
• DOI: 10.1002/macp.201400213

This study refers to the relationship between the macromolecular structure of two aromatic fluorinated polyamides and their physical properties, with emphasis on the overall and local chain mobility and their influence upon thermal transitions, dielectric relaxations, and gas permeability/selectivity. One polyamide contains naphthalene and 1,3,4‐oxadiazole units in the main chain, while the other is based on an aromatic asymmetrical diamine containing a phenoxy‐substituted benzophenone segment. Free‐standing, tough, and defectless films, having a hydrophobic character are prepared from these polymers and used afterward for various measurements. The polyamide films show excellent thermal stability, their decomposition starting around 400 °C. The dielectric spectroscopy data corroborate the dynamic‐mechanical analysis, showing distinct γ and β sub‐glass relaxations, which are discussed in correlation with the chemical structure of each polymer. The permeability of several gases through these membrane‐forming materials are measured and discussed with respect to the structural variations in the polyamide repeating unit. Correlations between the structural features and some of the properties of aromatic fluorinated polyamide are studied, which can be understood by investigating the influence of the polymeric architecture on the chain mobility. In particular, the effect of the chemical structure on thermal transitions and resistance, dynamic mechanical behavior, dielectric relaxations, molecular disorder, wetting characteristics, and gas permeation of these polymers is studied.