Design,Synthesis And Properties Of Fluorinated Block Copolymers

The segments of different nature are linked together by covalent bonds,so the incorporation of the fluoromonomer into the block polymer is expected to impart excellent properties to the polymer,and has broad application prospects,and has been widely concerned.In this paper,a series of well-defined,molecular weight controlled ABA tri-block copolymers were synthesized by reversible addition fragmentation chain transfer polymerization(RAFT)method,and were self-assembled to hydrophobic ordered porous polymer films.The prepared films were investigated for the application of microspheres and microfibers.(1)In this paper,a series of molecular chain transfer agents of different molecular weights,PtBA-CTA were synthesized by using S,S’-bis(a,a’-methyl-α"-acetic acid)trithiocarbonate(CTA)as the initial chain transfer agent.Further,a series of ABA-type triblock copolymers PtBA-b-PTFEA-b-PtBA(Mn=14900～27000 g·mol-1,Mw/Mn=1.09-1.28),fluorine content=15.3～23.0 wt-%),PtBA-b-PHFBA-b-PtBA and PtBA-b-PFNEMAs-b-PtBA with controlled structure and narrow molecular weight distribution were obtained respectively by RAFT polymerization of trifluoroethyl acrylate(TFEA),hexafluorobutyl acrylate(HFBA)and 2-(perfluorooctyl)ethyl methacrylate(FAEM).The chain structure and component of PrBA-b-PTFEA-b-PtBA、PtBA-b-PHFBA-b-PtBA and PtBA-b-PFAEM-b-PtBA tri-block copolymers were characterized by 1H NMR,19F NMR,GPC,FT-IR,UV and elemental analysis.(2)The self-assembly behavior of different molecular weight triblock polymers PrBA-b-PTFEA-b-PtBA in THF/H2O was investigated by dynamic self-organized precipitation(D-SORP).The polymers PtBA-b-PTFEA-b-PtBA with different molecular weights can self-assemble in THF/H2O(v:v=7:3)to form micelles with uniform particle size and morphology.(average particle size=365.7～536.7 nm,particle size distribution=0.134～0.159).(3)A porous polymer film with hydrophobicity was prepared by static breathing diagram using PtBA32-b-PTFEA42-b-PtBA32 as a film-forming material.The influence of polymer concentration,ambient temperature and cast film volume on the surface morphology,pore size and regularity of the pores of the porous membrane were investigated.The morphology and hydrophobic properties of the polymer porous membrane were analyzed by SEM and static water contact angle test.It was found that film have a hydrophobic angle of more than 90°,which proves that a hydrophobic porous film is obtained.(4)PrBA-b-PTFEA-b-PtBA hydrophobic microspheres and microfibers were prepared by electrospinning.The influence of spinning solution concentration,voltage and molecular weight on the fiber morphology were investigated.The morphology and surface element distribution of the fiber were tested by SEM and EDX,and the hydrophobicity was studied by static water contact angle test.The results show that the obtained electrospun fiber has a hydrophobic angle of up to 133°and good hydrophobic effect.