Figure 1.1. Energy harvesting from wind, solar, vibration, and thermal energy for self-powered systems 20

Figure 1.2. Working mechanism of triboelectric nanogenerator 22

Figure 1.3. The four-working mode of triboelectric nanogenerator (a) contact-separation mode... 23

Figure 1.4. Schematic diagrams of charge transfer: electron transfer mechanism 25

Figure 1.5. Schematic diagrams of the electron-cloud potential-well model for electron transfer 26

Figure 1.6. Schematic diagrams of ion transfer model (contact electrification in ionic polymers) 28

Figure 1.7. Schematic diagrams of ion transfer model (contact electrification between nonionic polymers) 28

Figure 1.8. Schematic diagrams of charge transfer: material transfer mechanism 29

Figure 1.9. Triboelectric series of different polymers 31

Figure 1.10. Schematic diagrams of triboelectric nanogenerator withequations for output performance 34

Figure 1.11. Different types of polarization as a function of frequency in polymers (Pint:... 37

Figure 1.12. Dipolar polarization and its effect in fluorinated polyurethanes 38

Figure 1.13. Ionic polarization and its effect in ionic polyurethanes and poly(ionic liquids) 38

Figure 2.1. Synthesis of thermoplastic polyurethane (TPU) 46

Figure 2.2. Synthesis of PDMS based fluorinated thermoplastic polyurethane (PDMS-FTPUs) 47

Figure 2.3. Biodegradable and flexible TPU; (a) Schematic illustration for thermoplastic... 51

Figure 2.4. FT-IR spectra of (a) TPU and (b) PDMS-TPUs 52

Figure 2.5. (a) FT-IR of PDMS-TPUs (NH3 stretching vibration peak), (b) FT-IR of PDMS-... 53

Figure 2.6. (d) Schematic illustration of intermolecular interaction in PDMS-TPUs chain 55

Figure 2.7. DSC thermograms of (a) TPU-HD and (b) PDMS-TPUs 56

Figure 2.8. (a) Full XPS spectra of TPU-HD, PDMS-TPU-HD, and PDMS-TPU-DFOD. (b)... 59

Figure 2.9. Contact angle of TPU and PDMS-TPUs 60

Figure 2.10. Mechanical property of designed TPUs: Tensile stress-strain behavior of TPU and... 62

Figure 2.11. Mechanical property of designed TPUs: Photo images of PDMS-TPU-DFOD at... 63

Figure 2.12. Mechanical property of designed TPUs: Stress-strain hysteresis loops of the cyclic... 65

Figure 2.13. Mechanical property of designed TPUs: Robustness test of TPU, PDMS-TPU-... 66

Figure 2.14. Working mechanism of PDMS-FTPU based triboelectric nanogenerator 68

Figure 2.15. Output performance of TPU with different ratios of PDMS diol.. 71

Figure 2.16. Output performance oi TENGs; (a) Output voltage (Voc) and (b) current (Isc)...[이미지참조] 73

Figure 2.17. Output performance of PDMS-TPU-DFOD under (a-b) different frequency and... 74

Figure 2.18. Comparison of triboelectricity between designed TPUs and other polymers... 75

Figure 2.19. Current (Isc) of TPU and PDMS-TPUs TENG with other polymers (Nylon, PET, PTFE) 76

Figure 2.20. Output performance of TPU and PDMS-TPUs (with PTFE, under 2Hz, 10N) 77

Figure 2.21. Power density of TPU and PDMS-TPU-HD and PDMS-TPU-DFOD based TENG... 79

Figure 2.22. (a) Voc of TENG before and after 100 times cycling bending test, (b) Stability... 80

Figure 2.23. (a) Circuit diagram of charging a capacitor using a TENG, (b) Measured voltages... 81

Figure 2.24. Dielectric constant of TPU and designed TPUs 83

Figure 2.25. Surface roughens of TPU and designed TPUs 85

Figure 2.26. SEM images of TPU and PDMS-TPUs 86

Figure 2.27. Surface potential of TPU and designed TPUs measure by KPFM 88

Figure 2.28. Biodegradability of TPU and designed TPUs; (a) Remaining weight of TPU and... 90

Figure 2.29. Remaining weight of TPU and designed TPUs as a function of degradation time... 91

Figure 2.30. Biodegradability of TPU and designed TPUs; (a) Biodegradable TENG based on... 93

Figure 2.31. Output performance of PDMS-TPU-DFOD based TENG 94

Figure 2.32. Cell viability test of (a) TPU and modified TPUs and (b) chain extender HD and DFOD 96

Figure 3.1. ¹H NMR spectra of imidazolium ionic liquid diol (IL diol) 101

Figure 3.2. Design of ionic polyurethane-based TENG (IPU-based TENG) (a) Schematic... 105

Figure 3.3. Synthetic route of IPUs for friction layer 106

Figure 3.4. Synthetic route of IPU-Mg for electrode 107

Figure 3.5. FT-IR spectra of (a) IPUs with different IL diol ratio and (b) IPUs with different... 111

Figure 3.6. ¹³c NMR spectra of PCL-PU (IL 0) and PCL-IPU (IL 2) 112

Figure 3.7. AFM images of IPUs for surface morphology 113

Figure 3.8. Young's modulus of the IPU (a) depends on IL diol ratio and (b) depends on the... 114

Figure 3.9. Electrical resistivity and resistance of IPU-Mg as a function of the Mg mass fraction 116

Figure 3.10. (a) Schematic illustrations of IPU based TENG (Contact area: 3x3 cm²,... 118

Figure 3.12. Output performance of IPU-based TENG: (a) Open-circuit voltage, (b) short-... 121

Figure 3.13. Output performance of IPU-based TENG: (a) Open-circuit voltage, (b) short-... 121

Figure 3.14. Comparison of power density of IPU-based TENGs as a function of externally... 122

Figure 3.15. (a) Open-circuit voltage, (b) short-circuit current and (b) power density of... 123

Figure 3.16. Output performance of IPU-based TENG: Long-term stability of PCL530-IPU... 125

Figure 3.17. Open-circuit voltage and short-circuit current of PCL530-IPU (IL 1, F)-based... 126

Figure 3.18. (a) Circuit diagram of charging a capacitor using the IPU-based TENG (b) Circuit... 127

Figure 3.19. (a) Circuit diagram of TENG connections with LEDs, (b) PCL530-IPU (IL 1, F)-... 128

Figure 3.20. (a) Open-circuit voltage and (b) short-circuit current of IPU-based TENG with... 129

Figure 3.21. Open-circuit voltages of IPUs-based TENGs contact with Nylon and triboelectric series 130

Figure 3.22. Surface potential of IPUs measured by KPFM (a) depends on IL diol ratio and (b)... 132

Figure 3.23. Electrical conductivity of IPUs as a function of the frequency 133

Figure 3.24. Schematic diagram showing leakage current according to IL concentration 134

Figure 3.25. Surface potential change of IPUs over time following friction with AFM tip 137

Figure 3.26. The effect of charge diffusion on IPUs according to time 138

Figure 3.27. Dielectric constant of IPUs with different ratio of IL diol 139

Figure 3.28. Scheme of IPU-based triboelectric nanogenerator (a) pristine PU (PCL-PU (IL 0))... 140

Figure 3.29. Dielectric constant of IPUs with different type of chain extender and molecular... 141

Figure 3.30. Schematic representation of the self-healing mechanism of IPUs and OM images... 143

Figure 3.31. OM images of self-healable PCL530-IPU (IL 1, F) in various healing temperature 144

Figure 3.32. Differential scanning calorimetry (DSC) of (a) IPUs with different ratio of IL diol... 146

Figure 3.33. OM images of self-healable IPUs with different ratio of IL diol at 75 ℃ 147

Figure 3.34. OM images of self-healable IPUs with different type of chain extender and... 148

Figure 3.35. Self-healing efficiency of IPUs at 75℃ for 1 hour (a) depends on IL diol... 149

Figure 3.36. (a) Output performance of the PCL530-IPU (IL 1, F)-based TENG before... 150

Figure 3.37. Remaining weight of IPU-based TENGs over time in PBS (at 37 ℃) 153

Figure 3.39. Photo images of IPU-based TENG according to degradation time(~300 days) 155

Figure 3.40. (a) Variation in open-circuit voltage and (b) short-circuit current of... 156

Figure 4.1. Overview concept and material design of the poly(ionic liquids)-based triboelectric... 169

Figure 4.2. Overview concept and material design of the poly(ionic liquids)-based triboelectric... 169

Figure 4.3. Synthetic scheme of polycations: (a) PMA (+), (b) PMA (+) imi (x＝95, 90, 80, or... 170

Figure 4.4. Synthetic scheme of polyanions: (a) PMA (-), (b) PMA (-) imi, (c) PS (-) (x＝95,... 171

Figure 4.5. Actual ratios of PMA-based polycations and polyanions determined by ¹H-NMR:... 172

Figure 4.6. Tribopolarity changes in PMA-based PIL - polycation and polyanion variants: (a)... 175

Figure 4.7. Tribopolarity changes in PMA-based PIL - polycation and polyanion variants:... 176

Figure 4.8. Tribopolarity changes in PMA-based PIL - polycation and polyanion variants:... 176

Figure 4.9. Output performance and electric properties of PMA-based PIL-polycation and... 178

Figure 4.10. Output performance and electric properties of PMA-based PIL-polycation and... 179

Figure 4.11. Output performance of PMA-based PIL (with PET) (a) Open-circuit voltage and... 180

Figure 4.12. Output performance of PMA-based PIL (with PI) (a) Open-circuit voltage and (b)... 180

Figure 4.13. Output performance of PMA-based PIL (with PFA) (a) Open-circuit voltage and... 181

Figure 4.14. Dielectric constant of PMA (+) at 3Hz 183

Figure 4.15. Dielectric constant of PMA (-) at 3Hz 183

Figure 4.16. Output performance and electric properties of PMA-based PIL-polycation and... 184

Figure 4.17. Schematic diagram showing leakage current according to IL concentration 185

Figure 4.18. Working mechanism of poly(ionic liquids)-based TENG, (a) Migration and... 187

Figure 4.19. Working mechanism of poly(ionic liquids)-based TENG (a) Migration and... 187

Figure 4.20. Changes in tribopolarity due to ion exchange and backbone modification in... 189

Figure 4.21. The output signal characteristics of a PMA-based imidazole PIL-triboelectric... 190

Figure 4.22. The output signal characteristics of a PS-based polyanion-triboelectric... 190

Figure 4.23. Changes in tribopolarity due to ion exchange and backbone modification in... 191

Figure 4.24. Changes in tribopolarity due to ion exchange and backbone modification in... 192

Figure 4.25. Changes in tribopolarity due to ion exchange and backbone modification in... 192

Figure 4.26. Output performance of PMA-based imidazole PIL (with Nylon) (a) Open-circuit... 193

Figure 4.27. Output performance of PMA-based imidazole PIL (with PET) (a) Open-circuit... 193

Figure 4.28. Output performance of PMA-based imidazole PIL (with PI) (a) Open-circuit... 194

Figure 4.29. Output performance of PMA-based imidazole PIL TENG (with PFA) (a) Open-... 194

Figure 4.30. Output performance of PS-based polyanioin TENG (with Nylon) (a) Open-circuit... 195

Figure 4.31. Output performance of PS-based polyanioin TENG (with PET) (a) Open-circuit... 195

Figure 4.32. Output performance of PS-based polyaniom TENG (with PI) (a) Open-circuit... 196

Figure 4.33. Output performance of PS-based polyanioin TENG (with PFA) (a) Open-circuit... 196