Preparation, Morphology And Property Of Hybrid Poly(Acrylic Acid) Microgels Via Miniemulsion Polymerization

Polymer microgels have become a hot research topic in the field of materials and are widely used in biological materials, drug controlled release, intelligent separation, catalysis, oil exploitation and other fields due to their excellent performance. The structure and size of microgels have an important influence on their function. PAA microgels contain a large number of carboxyl groups, and have good biocompatibility and pH responsiveness. In recent years, the researchers prepared multi-sensitive PAA hybrid microgels by using temperature sensitive monomers, magnetic nanoparticles and other nanoparticles. However, the monomer AA has high reaction activity, and PAA has good solubility in common polar organic solvents and easy to form macroscopic gel by hydrogen bonding. So it’s hard to prepare PAA mircogels by conventional emulsion polymerization. In this paper, PAN hybrid microspheres with uniform size were synthesized via miniemulsion polymerization, and then PAA hybrid microgels with cross-linked structure were obtained from the PAN hybrid microspheres under the basic conditions. The main contents are as follows:In the first chapter, the research progresses of polymer microgels in the recent years were summarized. Especially PAA microgels, as a pH sensitive microgels have wide application prospect in biological materials, medicine and so on. The preparation and modification methods of PAA microgels were also introduced.In the second chapter, PAN nanoparticles and magnetic Fe3O4/PAN hybrid nanoparticles were synthesized via miniemulsion polymerization method using AN, DVB and MPS modified FesO4 as main materials. Then PAA microgels and magnetic Fe3O4/PAN hybrid microgels were obtained from the nanoparticles under the basic conditions. This study investigated the effects of emulsifier type and cross-linker DVB contents on the morphology of PAN nanoparticles. The pH-responsive property of PAA microgels was investigated by measuring the swelling-deswelling behavior of PAA microgels under different pH buffer solutions. The results showed that PAN nanoparticles were regular spherical particles and have uniform size when using SDS as anionic emulsifier and with high content of DVB. PAA microgels were regular spherical particles and demonstrated excellent pH-responsive properties in different pH buffer solutions. The saturation magnetization values of the magnetic Fe3O4/PAN hybrid nanoparticles and magnetic Fe3O4/PAA hybrid microgels were 21.6 and 19.3 emu/g, and the hybrid microgels have good magnetic responsibility.In the third chapter, SiO2/PAN hybrid hollow microspheres were synthesized via in situ Pickering mini emulsion polymerization method using AN, DVB, MPS and TEOS as main materials, and then the PAA hollow microgels were obtained from SiO2/PAN hybrid hollow microspheres under the basic conditions. Furthermore, the magnetic SiO2/PAN hybrid hollow microspheres and magnetic PAA hybrid hollow microgels were obtained by the introduction of MPS modified Fe3O4. The results showed that SiO2/PAN hybrid microspheres were irregular spherical particles, and have obvious hollow structure; PAA hollow microgels were smooth and regular spherical particles, due to the removal of SiO2 nanoparticles after the hydrolysis recations. The saturation magnetization value of suppermagnetic Fe3O4/PAA hybrid microgels was 10.2 emu/g.In the fourth chapter, P(AN-NVCL) hybrid microspheres were synthesized via miniemulsion polymerization method using NVCL as temperature sensitive monomers, and then P(AA-NVCL) hybrid microgels were obtained from P(AN-NVCL) hybrid microspheres under the basic conditions. The structure, morphology and property of the products were characterized by Fourier-transformed infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), laser particles size analyzer and so on. The results showed that P(AA-NVCL) hybrid microgels were regular spherical particles with narrow size distribution. The hybrid microgels demonstrated excellent responsive properties in different pH buffer solutions and different temperature. The VPTT of microgels were in the range of 35～45℃.