Title Page
Abstract
Contents
Chapter 1. Introduction 17
1.1. PEDOT:PSS 17
1.1.1. Structure 17
1.1.2. Synthesis of PEDOT:PSS 19
1.1.3. Properties of PEDOT:PSS 22
1.2. Conductive PEDOT:PSS based nanocomposites 23
1.3. Stretchable and transparent PEDOT:PSS based composites 24
1.4. Shape memory PEDOT:PSS based composites 27
1.5. Research objectives 29
Chapter 2. Conductive PEDOT:PSS based nanocomposite electrode 31
2.1. Preparation of PEDOT:PSS-AgNP nanocomposites 33
2.1.1. Materials 33
2.1.2. In-situ synthesis of PEDOT:PSS-AgNP nanocomposites 33
2.1.3. Electrospinning of PEDOT:PSS-AgNP nanocompsites 34
2.2. Characterization of PEDOT:PSS-AgNP nanocomposites 35
2.3. In-situ synthesis of PEDOT-AgNP nanocomposites 36
2.3.1. Effect of solvent 36
2.4. In situ-synthesis of PEDOT:PSS-AgNP nanocomposites 40
2.4.1. Effect of PSS ion on PEDOT:PSS-AgNP formation 40
2.4.2. Effect of PVP additives on PEDOT:PSS-AgNP formation 43
2.5. Mechanism of PEDOT:PSS-AgNP formation 55
2.6. Application of PEDOT:PSS-AgNP to electrospun microfiber 58
2.7. Summary 61
Chapter 3. Stretchable and transparent PEDOT:PSS-based composite film electrode 62
3.1. Preparation of PEDOT:PSS/PDMS composite film 66
3.1.1. Materials 66
3.1.2. Fabrication of the PEDOT:PSS/PDMS composite film 66
3.2. Characterization of PEDOT:PSS/PDMS composite film 67
3.3. Morphology of PEDOT:PSS/PDMS composite film 67
3.3.1. Formation of bilayer structure 67
3.3.2. Formation of continuous PEDOT:PSS matrix - PDMS island structure 79
3.4. Electro-mechanic al and optical properties of PEDOT:PSS/PDMS composite film 95
3.5. Summary 105
Chapter 4. Shape memory PEDOT:PSS-based composite film 107
4.1. Preparation of PEDOT:PSS/epoxy composite film 109
4.1.1. Materials 109
4.1.2. Plasma treatment of PP substrate 109
4.1.3. Fabrication of PEDOT:PSS/epoxy composite film 111
4.2. Characterization of PEDOT:PSS/epoxy composite film 111
4.3. Surface modification through air plasma treatment 112
4.4. Morphology of PEDOT:PSS/epoxy composite film 118
4.4.1. Effect of plasma treated PP substrate 118
4.4.2. Effect of weight ratio 127
4.5. Shape memory PEDOT:PSS/epoxy composite film 131
4.6. Summary 137
Chapter 5. Conclusions 138
Reference 140
Korean abstract 155
Table 2-1. Composition of samples for synthesizing PEDOT:PSS-AgNP nanocomposites 34
Table 3-1. Surface energies of PEDOT:PSS and PDMS 77
Table 4-1. Surface energy of standard liquids 114
Table 4-2. Contact angle and surface energy of components of polymer blend 118
Table 4-3. Electrical and shape memory characterization according to plasma treatment time 136
Figure 1-1. Hierarchical structure of PEDOT/PSS. (a) specific sequence of monomer units (primary structure), (b) poly-ion complex (secondary structure), (c) colloidal... 18
Figure 2-1. Characterization of synthesized PEDOT-AgNP nanocomposites according to solvent, (a) XRD analysis and (b) FT-IR 38
Figure 2-2. FT-IR analysis of 3,4-ethylenedioxythiophene(EDOT) 39
Figure 2-3. Characterization of nanocomposites synthesized in acetonitrile as solvent with or without PSS- ion (a) FT-IR analysis, (b) XRD analysis, and (c) TGA analysis. 43
Figure 2-4. Characterization of nanocomposites synthesized in acetonitrile as solvent with or without PVP. (a) XRD analysis, (b) FT-IR analysis, and (c, d) TGA analysis. 47
Figure 2-5. TEM images of PEDOT:PSS-AgNP nanocomposites; (a, b) without PVP and (c, d) with PVP. 50
Figure 2-6. XPS analysis of PEDOT:PSS-AgNP nanocomposites with and without PVP. 52
Figure 2-7. XPS analysis of PEDOT:PSS-AgNP nanocomposites with and without PVP. (a) XPS S2p core-line spectra without PVP and (b) XPS S2p core-line spectra... 54
Figure 2-8. Schematic illustration of synthesis mechanism of PEDOT:PSS-AgNP nanocomposites according to additives. (a) Without PVP and (b) with PVP. 57
Figure 2-9. Surface morphology of fiber containing PEDOT:PSS-AgNP nanocomposite according to UV irradiation time. 59
Figure 2-10. UV-vis spectroscopy of fiber containing PEDOT:PSS-AgNP nanocmoposites to confirm silver reduction according to UV irradiation time. 60
Figure 2-11. Sheet resistance of fiber containing PEDOT:PSS-AgNP nanocmoposites to confirm silver reduction according to UV irradiation time 60
Figure 3-1. Surface morphology of the PDMS/PEDOT:PSS composite film with a PDMS to PEDOT:PSS weight ratio of 2:1. (a) Scanning electron microscopy... 70
Figure 3-2. Chemical structure of (a) PEDOT:PSS (b) PDMS and (c) Triton X-100 71
Figure 3-3. Cross-sectional SEM images of PDMS/PEDOT:PSS composite films with PDMS to PEDOT:PSS weight ratios of (a) 2:1, (b) 5:1, (c) 10:1, and (d) 15:1.... 74
Figure 3-4. Measured contact angles of distilled water on two substrates: (a) PET film and (b) Teflon film. 75
Figure 3-5. Optical cross-sectional images of free-standing PDMS/PEDOT:PSS composite films with a PDMS to PEDOT:PSS weight ratio of 5:1 prepared using... 78
Figure 3-6. Morphology of the PDMS/PEDOT:PSS composite film with a PDMS to PEDOT:PSS weight ratio of 2:1. (a) SEM images and (b) elemental silicon mapping... 82
Figure 3-7. Surface morphology of the PEDOT:PSS-rich bottom layer in the PDMS/PEDOT:PSS composite film according to the PDMS to PEDOT:PSS weight... 86
Figure 3-8. Characterization of PDMS islands in the bottom layer of the PDMS/PEDOT:PSS composite film: (a) PDMS island diameter distribution, (b)... 88
Figure 3-9. Diameter distribution and average diameter of PDMS islands in the bottom layer of the PDMS/PEDOT:PSS composite film according to the polymer... 89
Figure 3-10. (a) Optical microscopy images of the PDMS/PEDOT:PSS composite film with a PDMS to PEDOT:PSS weight ratio of 5:1 under different strain values.... 93
Figure 3-11. Optical microscopy images of PDMS/PEDOT:PSS composite films with different polymer weight ratios at rest and under 50% strain. (a) 2:1 (b) 5:1 (c)... 94
Figure 3-12. Electrical and optical properties of PDMS/PEDOT:PSS composite films. (a) Sheet resistance according to the weight ratio of PDMS and PEDOT:PSS, (b)... 99
Figure 3-13. Optical microscopy image showing the breakage of the segregated structures of PEDOT:PSS in the PDMS/PEDOT:PSS composite film under 150% strain 100
Figure 3-14. Demonstration of the electrical conductivity and transparency of the PDMS/PEDOT:PSS composite film in the stretched state using a circuit fabricated... 104
Figure 4-1. Schematic illustration of plasma treatment 110
Figure 4-2. FT-IR analysis of plasma treated PP film 113
Figure 4-3. Characterization of air-plasma treated PP substrate (a,b) Contacnt angle(D.I. water) (c) Surface energy 117
Figure 4-4. Surface morphology of the substrate/film interface(bottom layer) in the composite film with PEDOT:PSS to epoxy weight ratio of 1:2 according to air-... 120
Figure 4-5. Cross-sectional morphology of composite film according to plasma treatment time (a) (up) 0min (down) 5min (b) EDS line mapping of S atom (scale... 122
Figure 4-6. Development of continuous PEDOT:PSS matrix/ epoxy island morphology according to thermal curing time in the composite film with... 125
Figure 4-7. Epoxy island size according to thermal curing time in the composite film with PEDOT:PSS to epoxy weight ratio of 1:2 (a) Diameter bigger than 200um (b)... 126
Figure 4-8. Surface morphology inversion of bottom layer in the composite film according to PEDOT:PSS to epoxy in the solution (scale bar: 100um) 128
Figure 4-9. Surface morphology of the bottom layer in the composite film according to epoxy to PEDOT:PSS weight ratio in the solution(left) Optical image (middle)... 130
Figure 4-10. Characterization of epoxy island diameter according to weight ratio (a) size distribution of epoxy island (b) comparison 131
Figure 4-11. Thermomechanical characterization of PEDOT:PSS-epoxy composite film according to plasma treatment time (a) Storage modulus (b) tan δ 133
Figure 4-12. Shape memory effect of PEDOT:PSS composite film (a) Schematic illustration of shape memory behavior (b) Real image of shape memory effect 135
Figure 4-13. Relative resistance change according to shape memory state 136