Synthesis and characterization of novel piezoelectric nitrile copolyimide films for high temperature sensor applications

• Published in: Smart materials and structures 2014-10, Vol.23 (10), p.105015-7
• Main Authors: Maceiras, A, Martins, P, San Sebastián, M, Lasheras, A, Silva, M, Laza, J M, Vilas, J L, Gutierrez, J, Lanceros-Mendez, S, Barandiarán, J M, León, L M
• Format: Article
• Language: English
• Subjects: Anhydrides; Application fields; Applied sciences; Diamines; Differential scanning calorimetry; Exact sciences and technology; General equipment and techniques; high temperature sensor; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Nitriles; Physics; Piezoelectricity; polyimide; Polyimide resins; Polymer industry, paints, wood; Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing; Technology of polymers; Temperature sensors; Thermal stability
• ISSN: 0964-1726; 1361-665X
• DOI: 10.1088/0964-1726/23/10/105015

A series of amorphous polyimides and copolyimides that contained nitrile were obtained by a two-step procedure. The first step consisted of a polycondensation reaction of 4,4'-oxydiphtalic anhydride (ODPA) with one or two aromatic diamines, namely 1,3-Bis-2-cyano-3-(3-aminophenoxy)phenoxybenzene (diamine 2CN) and 1,3-Bis(3-aminophenoxy)benzene (diamine 0CN). In the second step, a thermal cyclodehydration converted each poly(amic acid) or copoly(amic acid) into their corresponding polyimide films. The piezoelectric response was improved after corona poling of the films. A maximum d33 modulus value of 16 pC N−1 was obtained for the polymide with two cyano groups (poly 2CN). The polarization also showed time and thermal stability up to 160 °C. Additionally, the thermal stability of the amorphous polyimides, ( -CN)APB ODPA, was studied by determining the glass transition temperature (T g ) and thermal decomposition through differential scanning calorimetry (DSC) and thermogravimetric analysis (TG), respectively. The high piezoelectric response (1-16 pC N−1), T g (160-180 °C) and degradation temperature (315-450 °C) make such polyamides excellent candidates for use as high temperature sensors.