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以偶氮二异丁腈为引发剂,含二甲氨基查尔酮基团的三硫代碳酸酯为链转移剂,在四氢呋喃溶剂中将N-异丙基丙烯酰胺(NIPAM)通过可逆加成断裂链转移(RAFT)自由基聚合制备了具有智能荧光特性的含二甲氨基查尔酮端基的聚N-异丙基丙烯酰胺(PNIPAM-DMAC),并通过红外光谱、核磁共振氢谱和紫外-可见光谱对其结构进行表征.研究了PNIPAM-DMAC聚合物的温敏性以及溶剂极性、温度、分子识别三重敏感的荧光特性.结果表明,PNIPAM-DMAC聚合物的低临界溶解温度(LCST)比聚N-异丙基丙烯酰胺(PNIPAM)聚合物低,且随着PNIPAM-DMAC聚合物分子量的降低、聚合物水溶液浓度的减小和α-环糊精(α-CD)的加入,其LCST温度均升高.随着溶剂极性的增加,PNIPAM-DMAC聚合物的荧光峰值波长基本上随着溶剂极性的增大而红移,荧光强度出现极小值和极大值,在甲醇和水中几乎无荧光,具有溶剂极性敏感的荧光特性;随着温度升高,PNIPAM-DMAC聚合物水溶液荧光强度显著增强,同时伴随荧光发射光谱的蓝移现象,且荧光随温度交替改变而呈现出可逆变化,具有可逆的温度“开/关”特性;α-CD的添加使得PNIPAM-DMAC聚合物水溶液的荧光强度增强,荧光峰值波长轻微蓝移,具有分子识别敏感的荧光特性.
Using azobisisobutyronitrile as initiator and trithiocarbonate containing dimethylamino chalcone group as chain transfer agent, N-isopropylacrylamide (NIPAM) was synthesized by reversible addition in tetrahydrofuran solvent Poly (N-isopropylacrylamide) with dimethylamino-chalcone end groups (PNIPAM-DMAC) with intelligent fluorescent properties was prepared by RAFT free radical polymerization and characterized by IR, 1H NMR and UV-Vis spectra were used to characterize the structure of the PNIPAM-DMAC. The thermosensitivity of the PNIPAM-DMAC polymer and the triple sensitive fluorescence properties of the solvent polarity, temperature and molecular recognition were investigated. The results showed that the low critical solution temperature LCST) is lower than that of the poly N-isopropylacrylamide (PNIPAM) polymer, and as the molecular weight of the PNIPAM-DMAC polymer decreases, the concentration of the aqueous polymer decreases and the addition of α-cyclodextrin (α-CD) , The LCST temperature increased.With the increase of the solvent polarity, the fluorescence peak wavelength of the PNIPAM-DMAC polymer basically red-shifted with the increase of the solvent polarity, and the fluorescence intensity showed a minimum value and a maximum value, Almost no fluorescence in methanol and water, with solvent polarity-sensitive fluorescence properties With the increase of temperature, the fluorescence intensity of PNIPAM-DMAC polymer aqueous solution significantly increased, accompanied by the blue shift of fluorescence emission spectra, and the fluorescence changed reversibly with the change of temperature, with reversible temperature “ON / OFF ”. The addition of α-CD enhanced the fluorescence intensity of the aqueous solution of PNIPAM-DMAC polymer with a slight blue-shift of the fluorescence peak wavelength and possessed the fluorescence characteristics of molecular recognition sensitivity.