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