The reversible addition fragmentation chain transfer (RAFT) polymerization of styrene in alcohol/water mixture mediated with the poly(N-isopropylacrylamide) trithiocarbonate macro-RAFT agent (PNIPAM-TTC) is studied and compared with the general RAFT dispersion polymerization in the presence of a small molecular RAFT agent. Both the homogeneous/quasihomogeneous polymerization before particle nucleation and the heterogeneous polymerization after particle nucleation are involved in the PNIPAM-TTC-mediated RAFT polymerization, and the two-stage increase in the molecular weight (M n ) and nanoparticle size of the synthesized block copolymer is found. In the initial homogeneous/quasi-homogeneous polymerization, the M n and nanoparticle size slowly increase with monomer conversion, whereas the M n and particle size quickly increase in the subsequent heterogeneous RAFT polymerization, which is much different from those in the general RAFT dispersion polymerization. Besides, the PNIPAM-TTC-mediated RAFT polymerization runs much faster than the general RAFT dispersion polymerization. This study is anticipated to be helpful to understand the polymer chain extension through RAFT polymerization under dispersion conditions.
Tanshinones act as common inhibitors to inhibit the aggregation of both hIAPP and Aβ, disaggregate preformed hIAPP and Aβ amyloid fibrils, and protect cells from hIAPP- and Aβ-induced toxicity.
Development of advanced fluorescent materials for constructing a secure and unclonable encryption is urgently required; however, their application in anti-counterfeiting applications is a great challenge. In this work, we proposed and synthesized a new type of upconversion nanoparticles@carbon dots@meso-SiO 2 nanohybrids by integrating two fluorescent materials of lanthanide-doped NaYF 4 upconversion nanoparticles (UCNPs) and carbon dots (CDs) into mesoporous silica (mSiO 2 ) to produce a novel sandwichlike core−shell structure and a dualmode fluorescence from UCNPs and CDs. By tailoring the UCNP core of different upconversion luminescence, all three kinds of dual-mode luminescent UCNPs@ CDs@mSiO 2 nanohybrids exhibited typical RGB upconversion luminescence under a 980 nm laser and blue downconversion luminescence under a 365 nm UV light. Due to strong the hydrophilic nature of the nanohybrids, they can be further fabricated into environmentally benign luminescent inks for creating highly secured, fluorescent-based, three-dimensional anti-counterfeiting barcodes via inkjet printing. The resultant UCNPs@CDs@ mSiO 2 inks with a dual-mode and tunable luminescence nature endow the inkjet-printing barcodes with an extremely high encoding capacity and high security. Such dual-mode fluorescent inks and barcodes are simple to fabricate, easy to view, efficient for coding, and difficult to clone, thus making them promising nanomaterials for anti-counterfeiting applications.
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