This paper presents a novel process to fabricate piezoelectric films from polyvinylidene fluoride (PVDF) polymer using integrated fused deposition modeling (FDM) 3D printing and corona poling technique. Corona poling is one of many effective poling processes that has received attention to activate PVDF as a piezoelectric responsive material. The corona poling process occurs when a PVDF polymer is exposed to a high electric field created and controlled through an electrically charged needle and a grid electrode under heating environment. FDM 3D printing has seen extensive progress in fabricating thermoplastic materials and structures, including PVDF. However, post processing techniques such as poling is needed to align the dipoles in order to gain piezoelectric properties. To further simplify the piezoelectric sensors and structures fabrication process, this paper proposes an integrated 3D printing process with corona poling to fabricate piezoelectric PVDF sensors without post poling process. This proposed process, named ‘Integrated 3D Printing and Corona poling process’ (IPC), uses the 3D printer’s nozzle and heating bed as anode and cathode, respectively, to create poling electric fields in a controlled heating environment. The nozzle travels along the programmed path with fixed distance between nozzle tip and sample’s top surface. Simultaneously, the electric field between the nozzle and bottom heating pad promotes the alignment of dipole moment of PVDF molecular chains. The crystalline phase transformation and output current generated by printed samples under different electric fields in this process were characterized by a Fourier transform infrared spectroscopy and through fatigue load frame. It is demonstrated that piezoelectric PVDF films with enhanced β-phase percentage can be fabricated using the IPC process. In addition, mechanical properties of printed PVDF was investigated by tensile testing. It is expected to expand the use of additive manufacturing to fabricate piezoelectric PVDF-based devices for applications such as sensing and energy harvesting.

No abstract

Bis-cyclometalated iridium complexes with electron-rich ancillary ligands exhibit high phosphorescence quantum yields in the deep red region.

Here we report five blue-phosphorescent platinum bis-phenylacetylide complexes with an investigation of their photophysical and electrochemical attributes.T hree of the complexes (1-3)a re of the general formula cis-Pt(CNR) 2 (C CPh) 2 ,i nw hichC NR is av ariably substituted isocyanide and CCPh is phenylacetylide. These isocyanide complexess erve as precursors for complexes of the general formula cis-Pt(CNR)(ADC)(CCPh) 2 (4 and 5), in which ADC is an acyclic diaminocarbene installed by amine nucleophilic addition to one of the isocyanides. All of the complexes exhibitd eep blue phosphorescence with l max~4 30 nm in poly(methyl methacrylate)(PMMA) thin films. Whereas isocyanide complexes 1-3 exhibit modestp hotoluminescence quantum yields(F PL), incorporation of one acyclic diaminocarbene ligandr esults in at hree-fold to 16-fold increasei nF PL while still maintaining an identicaldeep blue color profile.