Fe 3+ and Fe 2+ are common metal ions in natural water environments and creatures. The development of water-soluble fluorescent sensors for detecting Fe 2+ /Fe 3+ ions was of great significance. In this work, two kinds of boron fluoride dipyrrole (BODIPY) fluorescent small-molecules were synthesized firstly. One of the small molecules contains a thioester bond that can be used as a chain transfer agent to participate in the polymerization process, and the other contains an unsaturated C = C double bond at the meso position. Through the reversible addition-fragmentation chain transfer polymerization (RAFT) polymerization method, methacrylic acid (MAA) and methacrylamide (MAM) were used as the main monomers, and small molecular fluorescent monomers were introduced to the end of the main chain. In this way, fluorescent macromolecules were obtained. The polymers were water soluble owing to the presence of long enough hydrophilic carboxyl and amide chains. These fluorescent probes exhibit high sensitivity to Fe 2+ /Fe 3+ , good selectivity, and anti-interference of other ions. The detection limit for Fe 2+ was as low as 2.3 × 10 −7 M, and the detection limit for Fe 3+ can reach up to 4.5 × 10 −7 M. The results show that these probes can be used as good sensors to identify Fe 2+ and Fe 3+ . Moreover, the fluorophores could be incorporated into polymer chains as the RAFT reagents and/or functional monomers.
Peijian Sun,Yipeng Wang,Song Yang,Xuehui Sun,Bin Peng,Lining Pan,Yunzhen Jia,Xiaobing Zhang,Cong Nie
Heterocyclic aromatic amine molecularly imprinted polymer nanospheres with surface-bound dithioester groups (haa-MIP) were firstly synthesized via reversible addition-fragmentation chain transfer (RAFT) precipitation polymerization. Then, a series of core-shell structural heterocyclic aromatic amine molecularly imprinted polymer nanospheres with hydrophilic shells (MIP-HSs) were subsequently prepared by grafting the hydrophilic shells on the surface of haa-MIP via on-particle RAFT polymerization of 2-hydroxyethyl methacrylate (HEMA), itaconic acid (IA), and diethylaminoethyl methacrylate (DEAEMA). The haa-MIP nanospheres showed high affinity and specific recognition toward harmine and its structural analogs in organic solution of acetonitrile, but lost the specific binding ability in aqueous solution. However, after the grafting of the hydrophilic shells on the haa-MIP particles, the surface hydrophilicity and water dispersion stability of the polymer particles of MIP-HSs greatly improved. The binding of harmine by MIP-HSs with hydrophilic shells in aqueous solutions is about two times higher than that of NIP-HSs, showing an efficient molecular recognition of heterocyclic aromatic amines in aqueous solution. The effect of hydrophilic shell structure on the molecular recognition property of MIP-HSs was further compared. MIP-PIA with carboxyl groups containing hydrophilic shells showed the highest selective molecular recognition ability to heterocyclic aromatic amines in aqueous solution.Keywords:core-shell;molecularly imprinted polymers;hydrophilic shells;heterocyclic aromatic amines
Nanocapsules made of a cross-linked poly(dodecafluoroheptyl acrylate) shell were successfully synthesized by interfacial RAFT miniemulsion polymerization. The well-defined hollow fluorinated polymer structures were obtained by the subsequent removal of the liquid core materials. The core/shell ratio could be easily tuned up to 1:1 by changing the conditions. In the cases of high core/shell ratio of 1:2 and 1:1, the nanocapsules were severely deformed, which was improved by increasing the cross-linker amount up to 30 wt.-%. It was concluded that the utility of the interfacial RAFT miniemulsion polymerization overcame the thermodynamic and kinetic barriers in a conventional miniemulsion polymerization.
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