Multiple Sensitivity Of Polymer / Inorganic Composite Microgel Preparation And Adsorption Properties

Sensitive polymer microgels have been attracted a great attention in the biomolecule adsorption and separation among their many application fields. As moderate mild separation materials, polymer microgels possess several advantages over other kinds of adsorption materials, because of their high surface area, excellent surface property, good capacity of containing water, flexibility structure and less stimulation to the tissue. Meanwhile, they have better biocompatibility, controllability and designability. The structures and the chemical compositions of the used polymer microgels can be designed according the desired biommolecule and the separation condition, and easily controlled adsorption/desorption by means of changing the external stimulus. Up to now, the sensitive microgels used for protein separation are almost organic/organic composite materials. Besides, the studies concerning inorganic-oxide composite materials based on the microgel template method are mainly silica, zinc oxide, titanium dioxide and magnetic oxides. To the best of our knowledge, the synthesis of sensitive composite microgels containing zirconia has not been reported except our group.Based on our group's previous research work, this thesis mainly studies on the design preparation, and adsorption properties of multi-sensitive polymer/zirconia composite microgels. This work involves two aspects below:(1) The P(NIPAM-co-MAA) polymer microgels with thermo-and pH sensitive were prepared by the inverse suspension polymerization technique using N-isopropylacrylamide (NIPAM) and methacrylic acid (MAA) as the monomers. The P(NIPAM-co-MAA)/ZrO2 polymer/oxide composite microgels were in situ synthesized using the polymer microgel template method, ZrOCl2·8H2O as the reaction precursor. The P(NIPAM-co-MAA)/ZrO2 composite microspheres were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), X-ray powder diffraction (XRD) and thermogravimetric analysis (TGA). BSA as the model protein, the adsorption capability of P(NIPAM-co-MAA)/ZrO2 microspheres to BSA was studied by changing the ZrO2 amount, temperature and pH. The results showed that the inner walls of P(NIPAM-co-MAA)/ZrO2 polymer/inorganic composite microspheres became thicker and dense with the increasing of ZrO2 content. The adsorption capability of P(NIPAM-co-MAA)/ZrO2 composites to BSA greatly enhanced comparing with that of the pure polymer microgels, and the adsorption capability to BSA increased with the increasing ZrO2 contents in the composites. In addition, the amount of adsorbed BSA on P(NIPAM-co-MAA)/ZrO2 composite microspheres was larger under the high temperature and weak acidic conditions.(2) The P(NIPAM-St)/P(NIPAM-co-MAA) copolymer microgels with core-shell structure were prepared by two-step method, the emulsifier-free emulsion polymerization and the seed polymerization emulsion polymerization techniques. The P(NIPAM-St)/P(NIPAM-co-MAA)/ZrO2 polymer/inorganic composite microgels with the core-shell structure were controllably and easily obtained by using P(NIPAM-St)/P(NIPAM-co-MAA) as template and ZrOCl2 as precursor. The structure, morphology and size of P(NIPAM-St)/P(NIPAM-co-MAA)/ZrO2 composite microgels were characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM), Fourier transform infrared (FT-IR), and thermogravimetric analysis (TGA). In addition, the thermo-sensitivity of the prepared composite microgels was determined by means of laser particle size analyzer and turbidimetric method, respectively. The results of the BSA adsorption indicated that the adsorption capability of P(NIPAM-St)/P(NIPAM-co-MAA)/ZrO2 composite microgels to BSA are remarkably increased comparing with that of the pure polymer microgels. Moreover, the amount of adsorbed BSA markedly enhanced under the high temperature and the weak acidic conditions. According to the above results, the composite microgels could controllably realize adsorption or desorption of protein by simply adjusting environment temperature.