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The investigation of poly(propylene glycol) (PPG)-based
waterbornepolyurethane (WPU(PPG)) consisting of PPG,
dimethylolpropionic acid (DMPA)and isophorone diisocyanate
(IPDI) as solid polymer electrolyte has beendone in this thesis.
The swelling behavior of WPU(PPG) impregnated with 1 M
lithiumperchlorate (LiClO4) in propylene carbonate (PC) solution
was first studied,because the extent of liquid electrolyte is
considered to be responsible forthe ionic conductivity of
polymer electrolytes. Afterwards, conductivitiesof the
corresponding WPU(PPG) electrolytes were obtained by using
alternatingcircuit (AC) impedance. A good conductivity of
10-2~10-3 S/cm can be achievedfor WPU(PPG) electrolyte
containing 84% LiClO4/PC, which possesses a poormechanical
strength. On the other hand, the composite electrolyte (CE),by
means of mixing WPU(PPG), PEO and LiClO4/PC, which contains
littleLiClO4/PC, possessing both a high conductivity of ca. 10-3
S/cm and a goodmechanical strength. Furthermore, in order to
clarify the interaction between WPU(PPG) andLiClO4 for its
further application, fourier-transform infrared spectroscopy(
FTIR), X-ray photoelectron spectroscopy (XPS), differential
scanningcalorimetry (DSC), and electrochemical impedance
spectroscopy (EIS) wereutilized to monitor the phase change of
this WPU with the doped LiClO4concentration. Significant changes
occur in the FTIR spectrum of the WPUwith the added salt
concentration above 1 mmol/g WPU, indicating that aninteraction
with the lithium cation within the hard segment and between
thehard and soft phases occurs. The soft segment Tg increases
with increasingLiClO4 through the examination of DSC. XPS
results reveal that the componentof nitrogen polaron sites (N+)
increases with increasing LiClO4, and that thesaturation level
of salt doping is evidenced by the mole ratio of componentC-O to
C=O; meanwhile, a rearrangement in long chain of the soft domain
hasalso been observed when this WPU is doped with LiClO4. EIS
results indicatean increase in bulk conductivity as the salt
concentration is increased. Thepresent study concluded that the
characteristic phase separation of the WPUis altered as a result
of the interaction of lithium cations within the polarhard
domains, and that the phase intermixing is promoted by the
coupling ofthe hard and soft phases.
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