In Situ Ultraviolet Polymerization Using Upconversion Nanoparticles: Nanocomposite Structures Patterned by Near Infrared Light

Abstract

In this paper, we report an approach to polymerization of a nanocomposite containing UV-polymerizable organic material and inorganic, NaYbF4:Tm3+ core-based nanoparticles (NPs), which are optimized for upconversion of near infrared (NIR) to ultraviolet (UV) and blue light. Our approach is compatible with numerous existing UV-polymerizable compositions and the NaYF4: Yb, Tm3+ core-based NPs are much more stable against harsh conditions than NIR organic photo-initiators proposed earlier. The use of a core-shell design for the NPs can provide a suitable method for binding with organic constituents of the nanocomposite, while maintaining efficient NIR-to-UV/blue conversion in the NaYbF4 core. The prepared photopolymerized transparent polymer nanocomposites display upconversion photoluminescence in UV, visible and NIR ranges. We also demonstrate a successful fabrication of polymerized nanocomposite structure with millimeter/submillimeter size uniformly patterned by 980 nm irradiation of inexpensive laser diode through a photomask.

Tunable Quantum Photoinitiators for Radical Photopolymerization

“…Upconverting nanoparticles (UCNPs) are luminescent materials that are capable of emitting higher energy, lower wavelength photons on absorption of lower energy, higher wavelength incident light [ 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 ]. This photophysical phenomenon, which is referred to as photon upconversion, is based on an anti-Stokes process and involves sequential absorption of two or more low-energy photons, which enables the population of real, intermediate excited electronic states, followed by emission of a single high-energy photon.…”

“…Liu et al reviewed several strategies to increase up conversion luminescence efficiency, such as energy transfer modulation, surface passivation, host lattice manipulation, photonic crystal engineering, broadband sensitization, and surface plasmonic coupling. Rationally designed nanohybrids of UCNPs with enhanced photocatalytic activity behave as effective panchromatic radical photoinitiators [ 31 , 32 , 33 , 34 ].…”

“…Loir et al indicated that two pathways exist for initiation in quantum PIs, which involve surface mediated hole transfer ( Figure 1 ) [ 10 ]. Typical quantum PIs can be classified as semiconductor nanoparticles (NPs), such as TiO 2 , ZnO, and CdS NPs [ 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 ]; hybrid photoinitiators, including composites of metal nanoparticles (MNPs)/silanized metal (organic PIs, MNPs), fluorescent dyes, oligomeric silsesquioxane, and parent PIs, [ 17 ] semiconductor NPs (metal/graphene oxide) [ 18 , 19 , 20 , 21 , 22 , 23 ], and organometallic nanoparticles; panchromatic photoinitiators, namely upconverting nanoparticles (UCNPs) [ 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 ] and plasmonic nanoparticle composites (e.g., Ag@SiO 2 @UC@BFO–Au core@triple-shell); near-infrared photoinitiators, such as luminescent lanthanides (e.g., Ln 3+ , Yb 3+ , Er 3+ , and Ho 3+ ) and doped nanomaterials in a crystalline host lattice (NaYF 4 ); [ 31 ] magnetic nanoparticles, such as Fe 2 O 3 ; and metal core-shell nanoparticles (e.g., Ag@AgCl nanocubes) [ 35 , 36 ]. Figure 2 describes the polymerization of acrylic acid sodium (AAS) using the Ag@SiO 2 @UC@BFO-Au photoinitiator.…”

“…In general, nanoscale PIs are efficient for photo-curable polymerization applications in aqueous solutions and ultraviolet light (UV)-dependent stereolithography 3D printing [ 17 , 25 ]. They have superior conversion rates, a low risk of migration, exceptional cross-linking behavior, and good compatibility with aqueous media, owing to a large absorbance cross-section in UV–Vis region [ 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 ]. Quantum PIs enable the migration issue to be minimized due to their higher molecular weights.…”

Real-Time Imaging of Short-Wave Infrared Luminescence Lifetimes for Anti-counterfeiting Applications

“…RENPs provide a number of unique features for anti-counterfeiting and security applications, such as a color-tunable UC/DC luminescence with long decay time and excellent stability. In addition, RENPs can feasibly be introduced into polymeric/polymerizable materials for UC/DC PL pattern fabrication or transferred to the ink-like solutions compatible with commercially available inkjet printers for further pattern printing (da Luz et al, 2015;You et al, 2015;Jee et al, 2020). Among all the RENPs, Yb 3+ /Er 3+ doped UC nanoparticles have been widely recognized, extensively studied, and used in various applications due to their bright UC/DC emission.…”