Photothermal Polymer Nanocomposites of Tungsten Bronze Nanorods with Enhanced Tensile Elongation at Low Filler Contents

Abstract

We present polymer nanocomposites of tungsten bronze nanorods (TBNRs) and ethylene propylene diene monomers (EPDM). The combination of these components allows the simultaneous enhancement in the mechanical and photothermal properties of the composites at low filler contents. The as-synthesized TBNRs had lengths and diameters of 14.0 ± 2.4 nm and 2.5 ± 0.5 nm, respectively, and were capped with oleylamine, which has a chemical structure similar to EPDM, making the TBNRs compatible with the bulk EPDM matrix. The TBNRs absorb a wide range of near-infrared light because of the sub-band transitions induced by alkali metal doping. Thus, the nanocomposites of TBNRs in EPDM showed enhanced photothermal properties owing to the light absorption and subsequent heat emission by the TBNRs. Noticeably, the nanocomposite with only 3 wt% TBNRs presented significantly enhanced tensile strain at break, in comparison with those of pristine EPDM, nanocomposites with 1 and 2 wt % TBNRs, and those with tungsten bronze nanoparticles, because of the alignment of the nanorods during tensile elongation. The photothermal and mechanical properties of these nanocomposites make them promising materials for various applications such as in fibers, foams, clothes with cold weather resistance, patches or mask-like films for efficient transdermal delivery upon heat generation, and photoresponsive surfaces for droplet transport by the thermocapillary effect in microfluidic devices and microengines.

Transparent and photochromic poly(hydroxyethyl acrylate–acrylamide)/WO3 hydrogel with antibacterial properties against bacterial keratitis in contact lens

“…In most cases, the W metal loss feature at ∼43 eV may overlap WO 3 4f peaks at ∼37 eV, this could be the reason for the difference in the W4f spectra of p(HEA‐AAm)/WO 3 and p(HEA‐AAm)/b‐WO 3 hydrogels. Moreover, these intense peaks and well separated peaks correspond to the variable W 6+ , W 5+ , and W 4+ oxidation states in tungsten metal 61 (Figure S4(b)). The C1s scan spectra revealed a strong peak at ∼284 eV which could be due to CC/CH bonds; while the weak peak at ∼287 or ∼288.84 eV could be attributed to C═O, CO/CN bonds in the monomers, HEA/AAm (Figure S4(c)) 62 .…”

Functional Fibers, Composites and Textiles Utilizing Photothermal and Joule Heating

“…At a 7 wt % concentration of WO 2.72 , the polymer nanocomposites presented a photothermal temperature increase of up to 120 • C, with an extremely high heating rate of approximately 100 • C/min under IR irradiation at a power of 150 W ( Figure 2). Park et al reported polymer nanocomposite films of tungsten bronze nanorods (TBNRs, Na 0.33 WO 3 ) and ethylene propylene diene monomer (EPDM) [83]. TBNRs with a 14-nm length, a 2-to 3-nm width, and an oleyl amine surface capping layer were synthesized via one-pot solvothermal decomposition of ammonium metatungstate hydrate.…”

“…Conjugated polymers that have π-delocalization along their conjugated backbones have been one of the most useful semiconductors for optoelectronic devices such as light-emitting diodes [84], thin-film transistors [85], and photovoltaic cells [86]. In particular, when the structural units of both a donor and an acceptor comprise a repeating unit of the conjugated polymers, intramolecular charge transfer exists from the donor structure unit to the acceptor unit, thereby suppressing charge recombination between electrons and holes and light emission [82][83][84][85][86][87][88]. The subsequent intra-and intermolecular charge transfer processes emit heat rather than light, thus making the donor-acceptor-type conjugated polymers ideal materials for photothermal energy conversion applications [64,[87][88][89][90][91][92][93][94].…”

“…HR-TEM images of (a) Na 0.33 WO 3 TBNRs, (b) EPDM/TBNR nanocomposites with 3 wt % TBNR, (c) an optical image of an arm with a patch of a nanocomposite film with 3 wt % TBNRs under NIR irradiation by a medical NIR lamp, (d) NIR images of the arm at 0 and 10 min under NIR irradiation, and (e) photothermal temperature increases of the skin and patch including 3-wt % Na 0.33 WO 3 TBNRs under NIR light irradiation for 10 min, followed by temperature decreases after turning off the light. Reproduced from Ref [83]…”

Fabrication of polyester fabrics with tungsten bronze nanorods and a silane coupling agent for improved thermal storage and washing durability

“…Photothermal materials, including conductive, semiconductor, and magnetic materials, such as tungsten bronze and graphene oxide, absorb energy and convert it into heat when irradiated with long-wavelength near-infrared (NIR, 780–3000 nm) waves. These materials have a lower energy level than ultraviolet or visible light; hence, they can absorb NIR waves, with long wavelengths, which are harmless to the human body (Jeon et al, 2019 ). Tungsten trioxide (WO 3 ) is not suitable for NIR absorption; however, since alkali metal ions (M = Li + , Na + , K + , Cs +) are incorporated into the crystal structure of WO 3 , a part of the W 6+ in the crystal is reduced to W 5+ to form a conduction band.…”