Structures and Phases of ferroelectric polymers
Xiaojing ZhuSupervisor: Mike John Reece
Emiliano Bilotti
Outlines• Structures and Phases of PVDF
– α phase– αII(δ) phase– β phase– γ phase
• Phases of P(VDF/TrFE)
TT (all-trans)β-PVDFLT-P(VDF/TrFE)
TG+TG- (trans-gauche)α-PVDF
TTTTG+TTTG- (T3G+T3G-)γ-PVDFHT-P(VDF/TrFE)
Conformation of PVDF
Conformation of PVDF from C axis
Fig. Crystal structures of PVDFK.Tahiro et al., Phase Trans, Vol. 18,217(1989)
α Phase
arrows indicate the dipole direction normal to carbon chains
A.J.Lovinger. Ferroelectric Polymers. Science, Vol220:1116(1983)
αII (δ) Phase
A.J.Lovinger. Ferroelectric Polymers. Science, Vol220:1116(1983)
β Phase
F
Figure. β phase structure
Fig2. CF2 group zigzags
A.J.Lovinger. Ferroelectric Polymers. Science, Vol220:1116(1983)Ferroelectric Polymer Book
γ Phase
K.Tahiro et al., Phase Trans, Vol. 18,217(1989)
Conformation of PVDF from a-b plane
Process of PVDF
Form I β Form III γ
Form II α
Form IIp δ
MeltSolution
high-temperature annealing
high-pressure quenching
casting from DMA
slow cooling
slow cooling
drawing
casting from HMPTA casting from
acetone
polingpoling
high-temperature annealing
drawing
Fig. Interconversion between crystal modificationsK.Tahiro et al., Phase Trans, Vol. 18,217(1989)
Phase diagram for VDF/TrFE ratio copolymer(○:melting point;●:crystallization point, Δ:Curie point on heating; :Curie point on ▲cooling; □:ferroelectric-to-anti-ferroelectric transition point)
T. Furukawa .Advances in Colloid and Interface Science.71-72.183-208(1997)
Copolymer P(VDF/TrFE)
Phases of P(VDF/TrFE)
TT IR Spectra
100
60
40
20
0
80
1400 1200 1000 800 600 400Wavenumber/cm-1
Tran
smiss
ion/
%
Fig. infrared spectra of PVDF forms I and III
1280840
510
445
K.Tahiro et al., Phase Trans, Vol. 18,217(1989)
TGTG- in IR Spectra
100
60
40
20
0
80
1400 1200 1000 800 600 400Wavenumber/cm-1
Tran
smiss
ion/
%
Fig. infrared spectra of PVDF forms II and III
796
776 610 532
K.Tahiro et al., Phase Trans, Vol. 18,217(1989)
T3G+T3G- IR Spectra
100
60
40
20
0
80
1400 1200 1000 800 600 400Wavenumber/cm-1
Tran
smiss
ion/
%
Fig. infrared spectra of PVDF forms cast III and III
1134
1115
811
K.Tahiro et al., Phase Trans, Vol. 18,217(1989)