| Molecular imprinting technology(MIT) is one of cross-disciplinary technology which integrates the polymer chemistry, biomimetic biology. It was widely used in biomimetic sensors, chromatographic separation and other fields. Although there had rapid development of MIT in recent years, there are still challenges. It is well-known that the functional monomer and template molecules normally were self-assembled into host-guest complexes via hydrogen bond at room temperature, but the polymerization initiator requires higher temperature, which is likely to affect the association of the hydrogen bond, in the final, the performance of imprinted sites will be affected by the polymerization temperatures. Therefore, the preparation the molecular imprinted polymers at room temperature is the important subject with with great research value and challenges. Visible light activating room temperature RAFT polymerization is a kind of active controlled polymerization methods with some interesting properties, such as environmentally friendly, low-carbon and simple, which provides a powerful tool to the preparation MIPs at room temperature. In this paper, we use 2,4-D as template molecule constructed the MIP via visible light activating room temperature RAFT polymerization. The main results are as follow:(1) The design and synthesis the bifunctional monomers: in order to meet the needs of the template molecules, we designed and synthesized a kind of novel bifunctional monomers which play both as functional monomers and crosslinking agents. 2,2-bis((methacryloyloxy)methyl) propanoic acid(BMPA) and 2,2-bis((methacryloyloxy)methyl) butanoic acid(BMBA) monomers were synthetized by reacting methacryloyl chloride with 2,2-dimethylol propionic acid or 2,2-bis(hydroxymethyl) butyric acid. 1H NMR was used to analysis of the structure the bifunctional monomers.(2) The design of imprinted polymer: we studied the pre-assembly behavior between functional monomers and 2,4-D by UV-vis, which confirmed the ratio between bifunctional monomer and template molecule was 1:4. The adsorption properties of MIPs to 2,4-D were studied, We concluded that the BMPA was the righ bifunctional monomers, the MIP-BMPA adsorbed more 2,4-D. Henece, The optimum ratio of the monomer and the crosslinking agent was 1: 4.(3) The properties of molecular imprinted polymer: we used 2,4-D as the template molecule, BMPA as bifunctional monomer, EGDMA as the crosslinking agent, CESA as RAFT agents, TPO as the initiator and MeOH/H2O(3/1,m/m) as solvent, the MIP was prepared via the visible light activating room temperature RAFT polymerization. Fourier transform infrared spectroscopy, laser particle size analyzer, specific surface area and porosity analysis tools were used to characterize the MIP of structure, particle size, surface area, pore size. The results showed that MIPs were successfully prepared via the visible light activating room temperature RAFT polymerization and there was narrow particle size distribution. The BET surface area was 2.983 m2/g, the average pore size was 3.81 nm. The MIPs of adsorption kinetics, adsorption isotherm performance, equilibrium adsorption properties, selective adsorption properties and recycling experiment were studied by UV-vis spectroscopy and high performance liquid chromatography. The results showed that the adsorption kinetics of MIPs followed pseudo-first reaction kinetic model. The Scatchard analysis showed only one class of binding sites was formed in the MIPs under the concentration 0.05~0.5 mM. Moreover, the selective recognition of MIPs and NIP to 2,4-D was studied, revealed that MIPs showed higher and better selective recognition abilities to 2,4-D. |
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