Synthesis And Dielectric Properties Of Bilaterally Fluorinated Polyolefin-Polyacetylene Block Copolymers

Advanced polymer-based insulating materials with high energy storage density have developed fast in the recent years due to the huge potential of application.Using the third Grubbs' catalyst(Ru-III),poly[bis-3,5-(3',5'-bis(trifluoromethyl)biphenyloxy methyl)-phenyl norbornene pyrrolidine]-block-poly[4-(3',5'-bis(trifluoromethyl)biphenyl formate)-1,6-heptadiyne](PBTNPm-b-PFBHDn)was synthesized by ROMP-MCP process,and characterized subsequently.High dielectric constant of 30 at 1 k Hz-1 MHz with a low loss of 0.05 was achieved for PBTNP100-b-PFBHD25.In order to overcome the film defects caused by excessive rigid structure,polycyclooctene(PCOE)flexible chain was introduced into the copolymer backbone.The achieved P(BTNP100-coCOE100)-b-PFBHD25 displayed a high dielectric constant of 23,low dielectric loss of <0.003,and enhanced energy density of 4.52 J cm-3 at 165 MV m-1.Continuously,poly[N-2,3,4,5,6-pentafluorophenyl-norbornene-pyrrolidine]-block-poly[4-(3',5'-bis(trifluoromethyl)biphenyl formate)-1,6-heptadiyne](PFPNP-b-PFBHD)and poly[N-2,3,5,6-tetrafluoro-4-(3',5'-bis(trifluoromethyl)biphenyloxy)-phenyl norbornene pyrrolidine]-block-poly[4-(3',5'-bis(trifluoromethyl)biphenyl formate)-1,6-heptadiyne](PTBNP-b-PFBHD)were synthesized,which were characterized subsequently.DLS and TEM tests unveiled that the copolymers had unique morphology of alternating gray and black concentric circles.PFPNP100-b-PFBHD25 and PTBNP100-b-PFBHD25 displayed dielectric constant of 8 and 15,low dielectric loss of <0.003,and enhanced energy density of 11.45 J cm-3(450 MV m-1)and 4.99 J cm-3(284 MV m-1).Comparing the dielectric properties of the block copolymers,it was found that both polar groups and well-defind nanostructure had a great contribution to the dielectric properties.