title: Photopiezoelectric composites of azobenzene-functionalized polyimides and polyvinylidene fluoride.
abstract: Light is a readily available and sustainable energy source. Transduction of light into mechanical work or electricity in functional materials, composites, or systems has other potential advantages derived from the ability to remotely, spatially, and temporally control triggering by light. Toward this end, this work examines photoinduced piezoelectric (photopiezoelectric) effects in laminate composites prepared from photoresponsive polymeric materials and the piezoelectric polymer polyvinylidene fluoride (PVDF). In the geometry studied here, photopiezoelectric conversion is shown to strongly depend on the photomechanical properties inherent to the azobenzene-functionalized polyimides. Based on prior examinations of photomechanical effects in azobenzene-functionalized polyimides, this investigation focuses on amorphous materials and systematically varies the concentration of azobenzene in the copolymers. The baseline photomechanical response of the set of polyimides is characterized in cantilever deflection experiments. To improve the photomechanical response of the materials and enhance the electrical conversion, the polyimides are drawn to increase the magnitude of the deflection as well as photogenerated stress. In laminate composites, the photomechanical response of the materials in sequenced light exposure is shown to transduce light energy into electrical energy. The frequency of the photopiezoelectric response of the composite can match the frequency of the sequenced light exposing the films.
authors.affiliation: Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, OH, 45433, USA; Azimuth Corporation, 4134 Linden Avenue, Dayton, OH, 45432, USA.
authors.forename: Jeong Jae
authors.initials: JJ
authors.lastname: Wie
authors.forename: David H
authors.initials: DH
authors.lastname: Wang
authors.forename: Vincent P
authors.initials: VP
authors.lastname: Tondiglia
authors.forename: Nelson V
authors.initials: NV
authors.lastname: Tabiryan
authors.forename: Rafael O
authors.initials: RO
authors.lastname: Vergara-Toloza
authors.forename: Loon-Seng
authors.initials: LS
authors.lastname: Tan
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: White
mesh_terms: D001391:Azo Compounds / Q000737:chemistry*; D007094:Imides / Q000737:chemistry*; D055595:Mechanical Phenomena; D058105:Polymerization; D011145:Polyvinyls / Q000737:chemistry*; D013314:Stress, Mechanical; D005465:Fluorocarbon Polymers
chemical_list: D001391:Azo Compounds; D007094:Imides; D011145:Polyvinyls; C024865:polyvinylidene fluoride; D005465:Fluorocarbon Polymers; C009850:azobenzene
keywords: azobenzene; energy harvesting; piezoelectric polymer polyvinylidene fluoride; polyimide