Preparation Of Macroporous Polystyrene Microspheres With Atom Transfer Radical Polymerization

The rapid development of modern biotechnology industry promotes the development of efficient bioseparation media. As an effective method to solve the problem of stagnant mobile phase mass transfer, the large porous microspheres has attracted increasing attention in recent years owing to their advantages of low operating pressure, high flow velocity, high resolution, and suitable for scale-up. Institute of Process Engineering, Chinese Academy of Sciences has successfully prepared large porous polystyrene(PS) microspheres by surfactant reverse micelles swelling method. Because its non-specific adsorption can cause denaturation of proteins and other biological macromolecules, the strong hydrophobicity of the PS limits the types of media in the separation of biological macromolecules. This paper attempts to take advantage of atom transfer radical polymerization(ATRP) to synthesize amphiphilic diblock glycopolymer macromonomer to replace the surfactant in the original method, which is expected to form gigapore and realize hydrophilization of PS microspheres in one step during the preparation process. The paper studied the ATRP reaction of the hydrophobic polystyrene chain segment and the hydrophilic sugar chains, respectively. We preliminary prepared the amphiphilic diblock macromonomer with hydrophilic lipophilic balance value(HLB) by controlling the reaction conditions, which laid the foundation of preparing hydrophilic gigaporous PS medium.This dissertation includes four parts. The first part is the study of bulk ATRP of styrene. The effects of catalysts, ligands, initiators and temperature on ATRP of styrene were investigated in detail. Controlled/living bulk ATRP of styrene was achieved by using 1-PEBr as initiator, copper(I) bromide as catalyst, and N,N,N,N,N- pentamethyldiethyllenetriamine(PMDETA) as ligand at 90?C. After 4 h, the monomer conversion reached 51.8%, the practical molecular weight of polystyrene coincided well with the theoretical molecular weight of polystyrene, and the molecular weight distribution was 1.15. ATRP reaction kinetics of styrene showed ln(M0/M) is proportion to reaction time. Therefore, we can control the molecular weight of polystyrene by adjusting the reaction time and achieve controllable synthesis of the polystyrene.In the second part we studied the ATRP of MDAGal in the same way and get the optimal reaction condition at the same time. It was found that when 2-Ei BBr was used as initiator, CuBr/PMDETA as catalyze system, and the molecular ratio was 100/5/1/1 the polymerization can be controlled at 50 ℃ and the temperature was 50 ℃.The third part of the papaer is synthesizing diblock copolymer(PS-b- PMDGal) using PMDAGal as macroinitiator and styrene as hydrophobic monomer, and then the double bond was coupled on PS-b- PMDGal to achieve a macromonomer by Williamson reaction. Finally, The protective group, i.e. isopropyl on the the MAGL chain segment was removed by general method to form the hydrophilic segment of diblock polymer with a certain HLB value. The control of feed ratio of diblock can control the molecular weight and HLB value of the amphiphilic diblock sugar macromonmer. Water content method was used to measure the HLB value of diblock copolymer PS-b-PMDAGal.In the fourth part, the macroporous microspheres were prepared by surfactant reverse micelles swelling method. The surface morphology of macroporous microspheres was observed by SEM. Study shows that macroporous polymer microspheres were successfully prepared. The method developed in this study was convenient to prepare microspheres with larger pore size. The hydrophilic macroporous poly(styrene-divinyl benzene) microspheres prepared by surfactant reverse micelles swelling method have a good potentials in separation of biomacromolecules.