Preparation Of Bimodal Open-porous Hydrophilic Polystyrene Monoliths Via RAFT And Their Separation Application

With the rapid development of biological science and technology,biotechnology products play an increasing role in people’s daily life,such as food,medical treatment,disease surveillance and so on.The separation of biomacromolecules with complex structure is usually characterized with high difficulty,high cost and low activity recovery.Organic polymer monolithic columns have been widely used in the separation of biological macromolecules.However,the current organic polymer monolithic columns are difficult to take into account biocompatibility,mechanical strength and separation efficiency.In order to improve this situation,amphiphilic diblock glycopolymer(ADG)was first synthesized by reversible additionfragmentation chain transfer(RAFT)polymerization.Then,ADG and PF127 were used as oilphase surfactant and waterphase surfactant,respectively.Bicontinuous medium internal phase emulsion(MIPE)was prepared by synergistic assembly of the two surfactant at the oil/water interface.A bimodal open-porous polystyrene monoliths(BOPM)was finally prepared by RAFT emulsion polymerization using ADG as Macro RAFT agent.This paper is divided into three parts.The first part is the synthesis of ADG.Firstly,sugar-containing monomer(SDAGLu)was synthesized by Williamson etherification of diacetone-D-glucose with 4-chloromethylstyrene.Next,diblock polymer(PSPSDAGLu)was synthesized through two-step RAFT polymerization.ADG was finally obtained by the hydrolysis of PS-PSDAGLu.A series of ADG with different hydrophilic-lipophilic balance(HLB)values were obtained by adjusting the feeding ratios.The composition of ADG was characterized by infrared absorption spectroscopy and nuclear magnetic resonance hydrogen spectroscopy.Finally,the critical micelle concentration of ADG was determined by surface tensiometer,and it was determined that the reverse micelle structure could be formed at lower concentration.The second part is to prepare the BOPMs.Bicontinuous MIPE was first formed with the cooperation assembly of ADG and PF127 at the oil/water interface.Then,the BOPMs were prepared in one step through RAFT emulsion polymerization of MIPEs.The optimal conditions are as follows: stable bicontinuous MIPE can be obtained when the amount of water phase is 50 wt% of the emulsion,and the optimal HLB values of ADG range from 3 to 6;the amount of ADG in the oil phase is in the range of 10-15wt%.There is a certain relationship between the amount of PF127 and the HLB value of ADG.They work together for the adjustment process of the emulsion,forming a mosaic structure by the interaction of hydrogen bonding at the oil/water interface,thus stabilizing the oil-water interface.The results of mercury porosimetry and BET adsorption analysis show that the prepared monolithic columns have bimodal pore size distributions.The static water contact angle analysis proves that the participation of ADG can effectively mask the hydrophobic surface of the traditional polystyrene monolithic column skeleton and therefore improve its biocompatibility.In the third part,according to the hydrophilic characteristics of sugar-containing polymers on the surface of the BOPM,it was directly used as a hydrophilic interaction chromatograph(HILIC)y for the separation of glycoproteins.In addition,DEAE modified BOPM was further used as an anion exchange column,and the ion exchange capacity was determined to be 1.53 mmol/m L.Its rapid separation performance for mixed proteins was examined and verified by SDS-PAGE.The results show that DEAE-BOPM can quickly separate mixed proteins under high flow rate,and it has excellent mechanical strength and good mass transfer efficiency.The above results show that the hydrophilic bicontinuous polystyrene monolithic columns as prepared are expected to be widely used in the field of biological macromolecule separation.