1 The Danish Polymer Centre, Department of Chemical and Biochemical Engineering, Technical University of Denmark2 Department of Chemical and Biochemical Engineering, Technical University of Denmark3 Department of Energy Conversion and Storage, Technical University of Denmark4 Lund University5 Lund University
Novel triblock copolymers based on central poly( ethylene glycol) ( PEG) or poly( ethylene glycol-co-propylene glycol) (PEGPG) blocks with poly( pentafluorostyrene) (PFS) outer blocks were prepared by Atom Transfer Radical Polymerization (ATRP) with polydispersities on the order of 1.2 - 1.3. The bromoisobutyrate functionalized polyether macroinitiators with molecular masses (M-n) of approx. 10 000 enabled the addition of between 15 and 39 wt.% flanking PFS as found by H-1 NMR. In a similar fashion monomethoxy PEG ( MPEG, Mn 5 000) was added 50 wt.% PFS. Polymer electrolytes were prepared by complexing lithium bis( trifluoromethylsulfonyl) imide salt with the block copolymers and the liquid PEGPG precursor. The crystallinity and the melting points of the salted MPEG-b-PFS and triblock copolymers were found by DSC to be substantially suppressed. Short PFS blocks (T-g 33 degreesC) and the salted PEGPG blocks (T-g -65 degreesC) were immiscible and resulted in phase separation providing an elastomeric material in form of a physically cross-linked polyether network, even when the PFS block consisted of only about four monomer units. The salted triblock copolymers of PEGPG demonstrated conductivities of 10(-5.1) to 10(-4.9) S cm(-1) at 20 degreesC.
Journal of Materials Chemistry, 2004, Vol 14, Issue 19, p. 2902-2908