Synthesis of Highly Monodisperse Surface-Functional Microspheres by Photoinitiated RAFT Dispersion Polymerization Using Macro-RAFT Agents

Highly monodisperse PMMA microspheres have been synthesized by photoinitiated RAFT dispersion polymerization in the presence of a Macro-RAFT agent and a small molecular RAFT agent. A particle yield of over 90% was achieved within 3 h under UV irradiation at room temperature. The Macro-RAFT agent acts as a stabilizer and stabilizes the particles via formation of block copolymers in situ, and XPS analysis shows that about 29.9% of the particle surface was covered by the stabilizer. Various surface functional microspheres were prepared by using four kinds of Macro-RAFT agents, including poly­(methoxy poly­(ethylene glycol) acrylate)-based trithiocarbonate (P­(mPEGA)-TTC), poly­(methoxy poly­(ethylene glycol) acrylate-<i>co</i>-acrylic acid)-based trithiocarbonate (P­(mPEGA-<i>co</i>-AA)-TTC), poly­(acrylic acid)-based trithiocarbonate (PAA-TTC), and poly­(methoxy poly­(ethylene glycol) acrylate-<i>co</i>-4-vinylpyridine)-based trithiocarbonate (P­(mPEGA-<i>co</i>-4VP)-TTC). Ag/PMMA nanocomposite spheres were prepared using the P­(mPEGA-<i>co</i>-AA)-TTC stabilized microspheres. The PAA-TTC stabilized microspheres showed pH sensitivity. The colloidal stability of the particles prepared by this photoinitiated RAFT dispersion polymerization was also investigated

Phototriggered Base Proliferation: A Highly Efficient Domino Reaction for Creating Functionally Photo-Screened Materials

Phototriggered base proliferation as a highly efficient domino reaction is presented for creating functionally photo-screened materials, providing a strategy for the photopolymerization of shadow areas via chemically diffuse amines toward the nonirradiated areas during polymerization. By integrating proliferated amines with a peroxide initiator (dibenzoyl peroxide, BPO), phototriggered self-propagating polymerization of acrylate monomers in three-dimensional space was achieved. The advantages of this approach lie in its enhanced photosensitivity, increased propagating velocity, and elevated double-bond conversion (90%) while reducing the local high temperature and the minimum BPO concentration that sustain a traveling front. Astonishingly, the propagating velocity and local maximum temperature can be well-modulated by varied BPO concentration and the appropriate amount of BA-BPD (1-(9-fluorenylmethoxycarbonyl)-4-benzylpiperidine) concentration, respectively. Finally, functionally photo-screened material containing carbon nanotubes was successfully prepared by phototriggered base proliferation reactions

Photoinitiated RAFT Dispersion Polymerization: A Straightforward Approach toward Highly Monodisperse Functional Microspheres

A straightforward dispersion polymerization procedure for the synthesis of monodisperse functional polymeric microspheres is proposed in this article. This method overcomes the problems deriving from the highly sensitive nucleation stage by introducing both photoinitiation and a RAFT chain transfer agent to the reaction. The process of the formation and growth of particles in the procedure was investigated and found to be quite different from that in a traditional dispersion polymerization. Various kinds of PMMA-based functional microspheres with high size uniformity were synthesized in a single step by this strategy. The microspheres remained uniform in size, even at concentrations of cross-linker or functional comonomer up to 10 wt %

High-Throughput Screening and Confirmation of 22 Banned Veterinary Drugs in Feedstuffs Using LC-MS/MS and High-Resolution Orbitrap Mass Spectrometry

A new analytical strategy based on liquid chromatography–tandem mass spectrometry (LC-MS/MS) combined with accurate mass high-resolution Orbitrap mass spectrometry (HR-Orbitrap MS) was performed for high-throughput screening, confirmation, and quantification of 22 banned or unauthorized veterinary drugs in feedstuffs according to Bulletin 235 of the Ministry of Agriculture, China. Feed samples were extracted with acidified acetonitrile, followed by cleanup using solid-phase extraction cartridge. The extracts were first screened by LC-MS/MS in a single selected reaction monitoring mode. The suspected positive samples were subjected to a specific pretreatment for confirmation and quantification of analyte of interest with LC-MS/MS and HR-Orbitrap MS. Mean recoveries for all target analytes (except for carbofuran and chlordimeform, which were about 35 and 45%, respectively) ranged from 52.2 to 90.4%, and the relative standard deviations were <15% except for 20% for carbofuran. The decision limits (CCαs) for target analytes in formulated feed were between 2.6 and 23 μg/kg, and the detection capabilities (CCβs) were between 4.2 and 34 μg/kg. The method was successfully applied to screening of real samples obtained from local feed markets and confirmation of the suspected target analytes. It provides a high-throughput, sensitive, and reliable screening, identification, and quantification of banned veterinary drugs in routine monitoring programs of feedstuffs

High-Throughput Screening and Confirmation of 22 Banned Veterinary Drugs in Feedstuffs Using LC-MS/MS and High-Resolution Orbitrap Mass Spectrometry

A new analytical strategy based on liquid chromatography–tandem mass spectrometry (LC-MS/MS) combined with accurate mass high-resolution Orbitrap mass spectrometry (HR-Orbitrap MS) was performed for high-throughput screening, confirmation, and quantification of 22 banned or unauthorized veterinary drugs in feedstuffs according to Bulletin 235 of the Ministry of Agriculture, China. Feed samples were extracted with acidified acetonitrile, followed by cleanup using solid-phase extraction cartridge. The extracts were first screened by LC-MS/MS in a single selected reaction monitoring mode. The suspected positive samples were subjected to a specific pretreatment for confirmation and quantification of analyte of interest with LC-MS/MS and HR-Orbitrap MS. Mean recoveries for all target analytes (except for carbofuran and chlordimeform, which were about 35 and 45%, respectively) ranged from 52.2 to 90.4%, and the relative standard deviations were <15% except for 20% for carbofuran. The decision limits (CCαs) for target analytes in formulated feed were between 2.6 and 23 μg/kg, and the detection capabilities (CCβs) were between 4.2 and 34 μg/kg. The method was successfully applied to screening of real samples obtained from local feed markets and confirmation of the suspected target analytes. It provides a high-throughput, sensitive, and reliable screening, identification, and quantification of banned veterinary drugs in routine monitoring programs of feedstuffs