In cascade microreactor systems, a series of star polymers , in which poly(di(ethylene glycol) ethyl ether acrylate-co-oligoethylene glycol acrylate) served as the thermoresponsive arm and poly(N, N-dimethylaminoethyl acrylate) as the pH-responsive arm, were successfully prepared via the RAFT arm-first method. Results showed that the compositions of star products were close to the designed feed ratios, and the lower critical solution temperature (LCST) was affected by the arm composition and the external pH. Due to the more compact structure, star polymers had a smarter temperature response than the linear chains. Moreover, the Au nanoparticles formed by coordination reduction of star products could be efficiently applied in the 4-nitrophenol catalytic reduction process, and the reaction rate was affected by the arm composition, pH and temperature. This research demonstrated that polymer products with particular functions could be customized by tailoring the polymer structures in a facile microflow polymerization mode.
Developing water-soluble fluorescent probes has important scientific and practical significance. In this work, coumarin derivatives bearing -OH were obtained through the classical Knoevenagel reaction firstly. Secondly, -C C- on allyl bromide was introduced into coumarin by Williamson ether formation method. Thirdly, hydrazine hydrate was added to the coumarin derivatives, a polymerizable small molecular coumarin fluorophore containing probe was obtained successfully. And, the -COOH on di-thioester underwent an esterification reaction with –OH groups on β-cyclodextrin(β-CD) to prepare oligomer based reversible addition-fragmentation chain transfer(RAFT) reagents. Finally, three copolymer probes β-CD-PMAA-Coumarin, β-CD-PMAm-Coumarin, and β-CD-PHEMA-Coumarin were prepared via RAFT polymerization , in which C C-coumarin was used as the functional monomer and methacrylamide(MAm)/methacrylic acid (MAA)/hydroxyethyl methacrylate (HEMA) as the main monomers. The MALDI-TOF mass tests showed that the macromolecular level probes were successfully prepared. These polymer probes have molecular weights up to 5.4 kDa and have narrow molecular weight distributions (PDI≤1.31). With the assistance of water-soluble long-chained PMAm/PMAA/PHEMA and hydrophilic β-CD, the coumarin containing macromolecular fluorescent probes could be dissolved in water readily. These water soluble polymer fluorescent probes could recognize Fe 3+ /Fe 2+ and Cu 2+ ions with high sensitivity. The detection limit of Fe 3+ could be as low as 0.34 μM. This study successfully developed a promising technique for producing highly selective, fully water-soluble fluorescent macromolecular probes.
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