Approaches to achieve stable perovskite nanocrystals (PNCs) of interest, in particular those with large structural anisotropy, through protective coating of the inorganic shell at as ingle-nanocrystal (NC) level are comparatively few and limited in scope.R eported here is ar obust amphiphilicdiblock-copolymer-enabled strategy for crafting highly-stable anisotropic CsPbBr 3 nanosheets (NSs) by in situ formation of au niform inorganic shell (1st shielding) that is intimately ligated with hydrophobic polymers (2nd shielding). The dualprotected NSs displaya na rray of remarkable stabilities (i.e., thermal, photostability,m oisture,p olar solvent, aliphatic amine,etc.) and find application in white-light-emitting diodes. In principle,b ya nchoring other multidentate amphiphilic polymer ligands on the surface of PNCs,f ollowed by templated-growth of shell materials of interest, ar ich variety of dual-shelled, multifunctional PNCs with markedly improved stabilities can be created for use in optics,o ptoelectronics,a nd sensory devices.
Larger QDs result in a higher polymerization rate and a better fit of Mn,GPC with Mn,theoretical for PET-RAFT polymerization using CdSe QDs photocatalysts.
An unconventional but facile approach to prepare size-tunable core/shell ferroelectric/polymeric nanoparticles with uniform distribution is achieved by metal-free atom transfer radical polymerization (ATRP) driven by visible light under ambient temperature based on novel hyperbranched aromatic polyamides (HBPA) as a functional matrix. Cubic BaTiO3/HBPA nanocomposites can be prepared by in-situ polycondensation process with precursors (barium hydroxide (Ba(OH)2) and titanium(IV) tetraisopropoxide (TTIP)) of ferroelectric BaTiO3 nanocrystals, because precursors can be selectively loaded into the domain containing the benzimidazole rings. At 1200 °C, the aromatic polyamide coating of cubic BaTiO3 nanoparticles are carbonized to form carbon layer in the inert environment, which prevents regular nanoparticles from gathering. In addition, cubic BaTiO3 nanoparticles are simultaneously transformed into tetragonal BaTiO3 nanocrystals after high temperature calcination (1200 °C). The outer carbon shell of tetragonal BaTiO3 nanoparticles is removed via 500 °C calcination in air. Bi-functional ligand can modify the surface of tetragonal BaTiO3 nanoparticles. PMMA polymeric chains are growing from the initiating sites of ferroelectric BaTiO3 nanocrystal surface via the metal-free ATRP technique to obtain core/shell ferroelectric BaTiO3/PMMA hybrid nanoparticles. Changing the molar ratio between benzimidazole ring units and precursors can tune the size of ferroelectric BaTiO3 nanoparticles in the process of polycondensation, and the thickness of polymeric shell can be tailored by changing the white LED irradiation time in the organocatalyzed ATRP process. The dielectric properties of core/shell BaTiO3/PMMA hybrid nanoparticles can be also tuned by adjusting the dimension of BaTiO3 core and the molecular weight of PMMA shell.
Tetraphenylethylene (TPE)-functionalized nitroxide/alkoxyamine realized the “in situ observation” of the NMP process for both homogeneous and heterogeneous polymerization systems.
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