Near-infrared (NIR) photoinduced
chemical processes are highly
attractive for specific applications owing to the deep penetration
of NIR into the nontransparent materials including biological and
synthetic materials. Robust NIR photoinduced atom transfer radical
polymerization (photoATRP) was achieved using upconversion nanoparticles
(UCNPs) as an internal light converter to turn a 980 nm NIR light
to the wavelength of UV/vislight. This NIR photoATRP was capable of
polymerizing both hydrophobic and hydrophilic monomers at a low loading
of ppm concentrations of the CuBr2/tris(2-pyridylmethyl)amine
catalyst under the irradiation of a 980 nm NIR light (4 W/cm2) and UCNPs with reusable performance, providing well-defined polymers
with predetermined molecular weight, low dispersity, and excellent
chain-end fidelity. The switching of light “on/off”
showed an excellent temporal control of the polymerization. The NIR
photoATRP exhibited excellent penetrations through several visible
light-proof barriers using NIR light, and it may provide future directions
of photopolymerization in nontransparent systems, especially biological
systems containing photosensitive moieties.
A rapid oxygen-initiated and -regulated controlled radical polymerization was conducted under ambient temperature and atmosphere. The reaction between triethylborane and oxygen provides ethyl radicals, which initiate and mediate the radical polymerization. The controlled radical polymerization was achieved using RAFT chain transfer agents (CTA) without any process of removing oxygen, providing well-defined polymers with almost full conversion (>95 %) in a short period (15 min). High-throughput screening was used to discover the suitable conditions for various CTA and monomers. To show the versatility of this method, a polymer library containing 25 well-defined polymers with different compositions (block and statistical copolymers) and molecular weights were synthesized in 1 h via high-throughput synthesis technique. A polymer-painting technique was developed using this method, forming films with spatial control and excellent control in molecular weight and dispersity.
An environmentally friendly nanoparticle-supported catalyst was successfully prepared via in situ ionic complexation between imidazolium-based polymer ionic liquid (PIL) and poly(l-prolinamide-co-MAA). The physical and chemical properties of the obtained nanoparticles were characterized by TEM, FTIR, XPS, and static water contact angle experiments. The surface properties of the nanoparticle were found to significantly affect the catalytic performance. The nanoparticle with PIL outer facilitated the adsorption of reaction substrate in it. As a result, the catalytic system catalyzed the asymmetric Aldol reaction and multicomponent reaction in pure water efficiently. The catalytic system was able to be reused and recycled five times, and with no discernible loss in catalytic activity and enantioselectivity. These findings suggest that nanoparticles based on PIL may provide a new approach for preparing high performance supported catalysts for organic reactions in water. This technology also addresses issues associated with mass transfer in pure water reactions.
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