Preparations And Properties Of Some Magnetic Molecularly Imprinted Polymers Based On Attapulgite/Fe₃O₄ Nanoparticles

Molecular imprinting technique routed in natural antigen/antibody specific recognition mechanism,is a newly-developing method for synthesizing crosslinking polymer material emerging in the 20 thcentury.Because it possesses the characteristics of predictability,selectivity and practicability,its resulting polymer can selectively recognize and adsorb the target molecules.However,due to the limitation of the conventional preparing methods,the resulting polymers has usually some negligible issues,such as the ease of embedding the binding site,tedious time-consuming elution procedure,and low adsorption efficiency.But the surface imprinted means make a good solution to these problems now.In particular,the imprinting polymer film based on magnetic particles carrier not only have large specific surface area and resulting short elution time,but also can be separated quickly under external magnetic filed,which are beneficial to improve separation effect.In the thesis,caffeine and p-hydroxybenzoic acid are respectively chosen as templates to prepare some magnetic molecular imprinted polymers.The full text is divided into five parts as follows.Chapter 1.The mechanism,classification and development process of molecular imprinted technology were introduced in detail,and an advance on synthesis and applications,in environment and food,as well as biomedical analysis,of molecular imprinting polymers were summarized.Chapter 2.The reagents,instruments,experimental and theoretical analysis methods used in this thesis were introduced in detail.Chapter 3.Magnetic molecularly imprinted polymers(MMIPs(CAF))with core-shell structure were prepared using caffeine(CAF)as template,ATP/Fe3O4 as cores,acrylamide(AM)as functional monomer,ethylene dimethacrylate(EGDMA)as linkage agent and azo-iso-butyronitrile(AIBN)as initiator.The morphology and structure of the prepared polymer are characterized by Fourier-transform infrared spectrometer(FT-IR),scanning electron microscope(SEM),thermogravimetric analysis(TGA)and X-ray diffraction(XRD),and its performance of selective recognization and specific adsorption for CAF,as well as thermodynamic and kinetic behaviors of the adsorption process were studied.The results showed that the polymermicrospheres of well-dispersity and uniform size distribution,possessed a high affinity and excellent cyclic application performance for CAF with a maximum adsorption capacity of 2.94 mg/g at 25 ?,and the adsorption process obeyed Langmuir isotherm model and the pseudo-second-order kinetic equation.In addition,the polymer was also successfully applied in adsorption and separation of CAF and resulting spectrophotometric determination of CAF in commercial functional drinks in local supermarket with a high accuracy and selectivity.Chapter 4.Methacrylic acid(MAA)and acrylic amide(AM)were employed simultaneously as double monomers to prepare magnetic molecular imprinted polymers using surface imprinting method for further improving the sorption property of MMIPs(CAF)with single monomer synthesized in the third chapter.The results demonstrated that the prepare double monomers magnetic imprinting polymers(BM-MMIPs(CAF))possessed a better adsorption selectivity and higher adsorption ability than MMIPs(CAF),with a maximum adsorption capacity of 4.36mg/g for CAF at room temperature.At the same time,the thermodynamic and kinetic behaviors of the sorption process and stability of the polymers were also studied.At last,the prepared BM-MMIPs(CAF)was successfully used in pretreatment of the samples in spectrophotometric determination of CAF in commercial functional drinks with a satisfactory result.Chapter 5.Magnetic molecularly imprinted polymers(MMIPs(4-HBA)for p-hydroxybenzoic acid(4-HBA)with core-shell structure were prepared by heat initiation using ATP/Fe3O4 as cores,AM as functional monomer,EGDMA as linkage agent and AIBN as initiator,the crystal structure of Fe3O4 is maintained well in this synthesis process.The obtained stable polymers were spherical particles with pleated rough surface and uniform size distribution,and average diameter was about 1 ?m.Its highest adsorption capacity to 4-HBA was 11.84 mg/g.Especially,the prepared imprinting polymer showed a high adsorption specificity for 4-HBA and could capture selectively the target molecules in presence of most of its structural analogs,such as salicylic acid,sulfonic salicylic acid,benzoic acid,biphenol A,phenol and hydroquinone.