The Preparation And Application Of Monodisperse Polystyrene Particles With Functional Brushes

The Uniform hairy microshperes with functional block brushes on the surface were synthesised by RAFT method and the applications were also investigated. It was found that the thiol group modified hairy microshpere can be used in lysozyme refolding. In addition, the triblock brushes with environmental sensitivity can be used to prepare large scale three-Dimensional(3D) regular colloidal crystals.The uniform cross-linked PS particles grafting PNIPA-b-PGMA onto the surface were prepared by Reversible Addition-Fragmentation Transfer (RAFT) technology with three steps. Firstly, the monodisperse cross-linked PS paticles were synthesized by emulsifer-free polymerization. Secondly, the Z group of RAFT agent was anchored on the surface of crosslinked PS particles. Finally, functional monomers NIPA and GMA were added one by one, then the block PNIPA-b-PGMA brush was obtained by UV light-initiated RAFT polymerization. Moreover, DTT was used to modify the microshpere in order to bring in the thiol group. After the preparation, the hairy microshpheres were applied on the refolding of lysozyme. The thiol-group content of brush was considered as the influencing factor to refolding activity, which more thiol group had significantly obvious. Moreover, the thiol-modified microshpere also can be recycled for use. In summary, the thiol-riched hairy microshpere will be an effective agent assisting the refolding of proteins with disulfide bond.The hairy microshperes with PVP-b-PNIPA-b-PAA or PAA-b-PNIPA-b-PVP triblock brushes were synthesized by the same method as mentioned above. It demonstrated that both PVP and PAA brushes are the pH-sensitive. The PVP brush can be collapsed in the base and stretched in the acid. The PAA brush is just the reverse. The second block PNIPA has temperature-sensitive and can be collapsed when temperature is high. In comparison with the primary condition, the thickness of triblock brush is significantly decreased when middle PNIPA block is firstly collapsed and stretched again using the change of temperature because the PVP with postive charge and PAA with negative charge can be absorbed together to form a coil structure. These two hairy microshperes were used to prepare the colloidal crystals. The film-forming characteristics were discussed by changing the brush thickness, temperature and pH value. The results showed that the porosity can be increased by increasing brush thickness. In addition, the high temperature was a negative factor in the film forming.