Iron-catalyzed Green Electrochemically Mediated Atom Transfer Radical Polymerization And Design Of PEO-based Block Copolymer

Atom transfer radical polymerization(ATRP)is one of the fastest growing fields in polymer science.Various well-defined homopolymer or copolymer with low polydispersity can be compounded.However,current chemical industrial have brought great environment hazards.Therefore,researchers are committed to the concept of green chemistry.Iron catalysts are widely used in the ATRP system because of the low toxicity,low price,abundant reserves and good biocompatibility.In Iron-based ATRP system,organic ligands not only promote the dissolution of iron salts in organic media,but also adjust the redox potential of metal centers.However,organic ligands lead to unavoidable pollution and increase the difficulty in separating metal catalyst complexes,which makes ATRP violate the principle of environmental friendliness.In order to build a green ATRP system,this article has carried out the following work:(1)Five polar solvents,NMP,DMF,DMI,MeCN and PEG200 were studied in the iron-catalyzed eATRP system.The results show good controllability in five polar solvents,which show that the polar solvents have strong coordination with iron catalyst in the eATRP system.NMP exhibits the fastest polymerization rate because the methyl group in NMP increases the ability of the amide group to coordinate with iron salt.Compared to phosphorus-containing or nitrogen-containing complexes,these polar solvents are inexpensive and low toxicity,which is of great significance for the idea of green chemistry.(2)PEO-based block copolymers were prepared by iron-catalyzed ATRP with ligand-free.The system contains three components: monomer,macroinitiator PEO-Br,and iron catalyst.PEO-Br with different molecular weight show good controllability,which indicate that PEO-Br not only have initiation effect,but also coordinate with Fe catalyst.Although polar solvents are inexpensive,they still contain a little toxicity and are volatile.In this section,we constructed ligand-free ATRP system,which is in accordance with green chemistry.Block copolymers prepared by ATRP without ligands are successfully used in polymer electrolytes.Polymer electrolyte membranes with good electrical conductivity can be obtained at room temperature.