TY - JOUR
T1 - Sub-nanoscale Surface Engineering of TiO2Nanoparticles by Molecular Layer Deposition of Poly(ethylene terephthalate) for Suppressing Photoactivity and Enhancing Dispersibility
AU - La Zara, Damiano
AU - Bailey, Maximilian R.
AU - Hagedoorn, Peter Leon
AU - Benz, Dominik
AU - Quayle, Michael J.
AU - Folestad, Staffan
AU - Van Ommen, J. Ruud
PY - 2020
Y1 - 2020
N2 - In this work, we report molecular layer deposition (MLD) of ultrathin poly(ethylene terephthalate) (PET) films on gram-scale batches of ultrafine particles for the first time. TiO2 P25 nanoparticles (NPs) are coated up to 50 cycles in an atmospheric-pressure fluidized-bed reactor at 150 °C using terephthaloyl chloride and ethylene glycol as precursors. Ex-situ diffuse reflectance infrared Fourier transform spectroscopy, thermogravimetric analysis, and transmission electron microscopy show the linear growth at 0.05 nm/cycle of uniform and conformal PET films, which are unattainable with conventional wet-phase approaches. The sub-nanoscale and nanoscale PET films not only suppress the photocatalytic activity of TiO2 NPs by hindering the access of water and reactant molecules to the TiO2 surface but also improve the dispersibility of TiO2 NPs in both organic and aqueous media. Still, the bulk optical properties, electronic structure, and surface area of TiO2 are essentially unaffected by the MLD process. This study demonstrates the industrial relevance of MLD to simultaneously suppress the photoactivity and enhance the dispersibility of commercial TiO2 P25 nanopowders, which is crucial for their use for example as UV-screening agents in sunscreens and as white pigments in paints. Moreover, by rapidly modifying the surface properties of particles in a controlled manner at the sub-nanometer scale, particle MLD can serve many other applications ranging from nanofluids to emulsions to polymer nanocomposites.
AB - In this work, we report molecular layer deposition (MLD) of ultrathin poly(ethylene terephthalate) (PET) films on gram-scale batches of ultrafine particles for the first time. TiO2 P25 nanoparticles (NPs) are coated up to 50 cycles in an atmospheric-pressure fluidized-bed reactor at 150 °C using terephthaloyl chloride and ethylene glycol as precursors. Ex-situ diffuse reflectance infrared Fourier transform spectroscopy, thermogravimetric analysis, and transmission electron microscopy show the linear growth at 0.05 nm/cycle of uniform and conformal PET films, which are unattainable with conventional wet-phase approaches. The sub-nanoscale and nanoscale PET films not only suppress the photocatalytic activity of TiO2 NPs by hindering the access of water and reactant molecules to the TiO2 surface but also improve the dispersibility of TiO2 NPs in both organic and aqueous media. Still, the bulk optical properties, electronic structure, and surface area of TiO2 are essentially unaffected by the MLD process. This study demonstrates the industrial relevance of MLD to simultaneously suppress the photoactivity and enhance the dispersibility of commercial TiO2 P25 nanopowders, which is crucial for their use for example as UV-screening agents in sunscreens and as white pigments in paints. Moreover, by rapidly modifying the surface properties of particles in a controlled manner at the sub-nanometer scale, particle MLD can serve many other applications ranging from nanofluids to emulsions to polymer nanocomposites.
KW - improved dispersion
KW - inorganic-organic nanocomposite
KW - molecular layer deposition
KW - organic coating
KW - polyethylene terephthalate
KW - sub-nanoscale
KW - suppressed photoactivity
KW - surface engineering
KW - TiO
UR - http://www.scopus.com/inward/record.url?scp=85091047604&partnerID=8YFLogxK
U2 - 10.1021/acsanm.0c01158
DO - 10.1021/acsanm.0c01158
M3 - Article
SN - 2574-0970
VL - 3
SP - 6737
EP - 6748
JO - ACS Applied Nano Materials
JF - ACS Applied Nano Materials
IS - 7
ER -