Micropatterning of the Ferroelectric Phase in a Poly(vinylidene difluoride) Film by Plasmonic Heating with Gold Nanocages

Abstract

Polymer thin films with patterned ferroelectric domains are attractive for ab road range of applications, including the fabrication of tactile sensors,i nfrared detectors, and non-volatile memories.H erein, we report the use of gold nanocages (AuNCs) as plasmonic nanostructures to induce af erroelectric-paraelectric phase transition in ap oly(vinylidene fluoride) (PVDF) thin film by leveraging its photothermal effect. This technique allows us to generate patterned domains of ferroelectric PVDF within just afew seconds.The incorporation of AuNCs significantly enhances the pyroelectric response of the ferroelectric film under near-infrared irradiation. We also demonstrate the use of such patterned ferroelectric films for near-infrared sensing/imaging.Photothermal conversion based on plasmonic nanostructures has been explored to induce localized heating of the host medium, which is highly attractive for ab road range of applications,i ncluding biomedicine, [1] steam generation, [2] optofluidics, [3] and acceleration of chemical reactions. [4] The heat transfer from ap lasmonic nanoparticle to the host medium starts with the absorption of photons by localized surface plasmon resonance (LSPR) and the conversion of part of the photon energy into heat, which is then transferred to the surrounding medium. [5] Previous studies have demonstrated the use of such plasmonic heating to induce phase transitions in water, [2b] thermoresponsive copolymers, [6] and phase-changing materials. [7] These plasmon-assisted phase transitions in the host media can lead to various interesting physical changes in material properties,o ffering ap owerful approach to design and fabricate functional devices for an array of applications.Ferroelectric polymers have attracted much interest as the next-generation piezo/pyroelectric materials owing to their feasibility in terms of solution processing, flexibility,low cost, and non-toxicity.P oly(vinylidene fluoride) (PVDF), one of the most commonly used ferroelectric polymers,possesses a, b,a nd g phases. [8] Its piezo/pyroelectric properties have enabled the fabrication of film-based tactile sensors,infrared detectors,e nergy-harvesting devices,a nd non-volatile memories.T orealize these applications,itiscritical to pattern the ferroelectric phase (either b or g)rather than the paraelectric a phase.T hus far,s uch patterning has mainly been achieved by irradiation etching [9] and imprinting lithography. [10] The former method may deteriorate the ferroelectric properties whereas it is not easy to obtain af reestanding and smooth polymer film using imprinting lithography without requiring multiple steps.P VDF generally exhibits ap hase transition from the ferroelectric to the paraelectric phase when heated to temperatures near its melting point or the ferroelectric Curie temperature (ca. 170 8 8C). [11] As an alternative approach, Wegener et al. reported the patterning of aP VDF film by scanning af ocused laser beam across the top aluminum electrode. [12] This method successfully generated depolar...

Enhancing the tactile and near-infrared sensing capabilities of electrospun PVDF nanofibers with the use of gold nanocages

“…For the AuNC/PVDF nanofibers, the strong absorption in the range of 300−500 nm can be attributed to PVDF and/or the nanofiber morphology. 17…”

“…8–11 In addition, the polymer chains can also be aligned to obtain the β phase when PVDF is dissolved in a mixture of acetone and N, N-dimethylformamide (DMF), and electrospun into nanofibers by leveraging the strong electrical field and mechanical stretching force associated with electrospinning. 12–14 Moreover, it has been reported that the incorporation of nanoparticles made of materials such as Ag, 15,16 Au, 17–19 and ZnO 20 could play a positive role in aligning the polymer chains and thus enhancing the piezoelectric response. It was proposed that the strong electrostatic interactions between the positively charged nanoparticles and the negatively charged fluorine atoms in the polymer backbone could produce interfacial polarization on the crystalline phase to facilitate the formation of the β phase.…”

Pyroelectric waste heat energy harvesting using the Olsen cycle on Pb(Zr, Ti)O3-Pb(Ni, Nb)O3 ceramics

“…To date, various structural designs of pyroelectric materials (e.g., micropatterning and microchannels) using micromanufacturing and/or sand blasting techniques have been proposed to enhance heat transfer by convection or radiation in PVDF thin films 64,65 and PZT ceramics [66][67][68][69][70][71][72] in order to improve the energy conversion efficiency of materials and devices. Note that reducing the sample thickness should not change the energy per volume N D achieved under quasiequilibrium conditions.…”

Reverse Thinking of the Aggregation‐Induced Emission Principle: Amplifying Molecular Motions to Boost Photothermal Efficiency of Nanofibers**

“…We then investigated the photothermal conversion efficiency of BPBBT molecules in core–shell fiber and their durability. The photothermal conversion efficiency could be calculated by following equation: [28] …”