General Conclusions

We have described, in this dissertation, miscibility behavior, interaction mechanism and ionic conductivity of LiClO4/PEO/PCL, LiClO4/MPEG-PCL, and LiClO4/PVP-co-PMMA blends-based electrolyte systems by using DSC, FTIR spectroscopy, solid-state ⁷Li NMR, and ac impedance and made some conclusions as follows:

(a) Although each of the three individual binary pairs, in the LiClO4/PEO/PCL ternary blend, is fully miscible, a closed-loop immiscibility region exists in the ternary blend’s phase diagram. Lithium cation more preferably coordinates with ether oxygen atom of PEO rather than with the carbonyl group of PCL. When LiClO4 salt is added to the PEO/PCL binary blend, the PCL component tends to be excluded, which causes the phase separation of these ternary blend. Moreover, the presence of a small content PCL in the PEO phase is able to retard or inhibit crystallization because PEO and PCL are fully miscible in the amorphous phase at all compositions. This factor is responsible for the observed increase in ionic conductivity of LiClO4/PEO/PCL blend.

(b) The presence of PCL in the MPEG-PCL block copolymer tends to suppress the crystallinity of MPEG as a consequence of the miscibility between MPEG and PCL. Thus, the ionic conductivity of LiClO4/MPEG-PCL blend system at room temperature is higher than that of LiClO4/MPEG-based polymer electrolyte.

Besides, raising the concentration of LiClO4 salt or increasing the length of the PCL block in the LiClO4/MPEG-PCL blend increases the relative intensity of stretching band for the “complexed” carbonyl group in IR spectra. However, the relative intensities of the “complexed” carbonyl and “complexed” ether stretching

groups tend to be changed in different directions for some compositions of the LiClO4/MPEG-PCL blend system when the temperature is increased.

(c) A single Tg was observed for PVP-co-PMMA random copolymers and implied that these copolymers were miscible. In addition, the negative deviation of Tg of PVP-co-PMMA was obtained from DSC analyses because PMMA moiety played an inert diluent role to eliminate the self-association of PVP molecules. For the binary blend of LiClO4/PVP, an unusually phenomenon was observed that the addition of low content of LiClO4 salt tends to reduce the strong dipole-dipole interaction within PVP and leads to the decrease the value of Tg of PVP; then, the further increase of LiClO4 promotes Tg of PVP increasing. Combining the effects of ni and µi on ionic conductivity, consequently, it is reasonable to explain that the maximum ionic conductivity is appearing at LiClO4/VP57 (20/80).

In summary, we found that although a polymer matrix, such as PEO or PVP, is excellent for dissociating lithium salts, the barriers, such as crystallization or strong self-association, may exist to limit the transportation of the dissolved ions.

Interestingly, such barriers may overcome by incorporating other polymers like PCL or PMMA, which even possess less ability to dissolve salts than that of PEO or PVP.

Whether the method of incorporating polymers is through blending or copolymerizing, the resultant materials tend to increase their ionic conductivity while blending with LiClO4 salt. These phenomena can be evidenced by detecting the miscibility behavior and interaction mechanism using DSC, FTIR, and solid-state NMR techniques.

Furthermore, they carry key messages for the ionic conduction process and demonstrate how important it will be in the future to adopt a more fundamental view of solid-state polymer electrolytes.

List of Publications

1. Chen, Hsien Wei; Chiu, Chun Yi; Chang, Feng Chih “Conductivity Enhancement Mechanism of the PEO/Modified-Clay/LiClO₄ Systems”, Journal of Polymer Science: Polymer Physics Edition 2002, 40, 1342.

2. Chen, Hsien Wei; Chiu, Chun Yi; Wu, Hew Der; Shen, I Wen; Chang, Feng Chih

“Solid State Electrolyte Enhancement Based on Poly(ethylene oxide), Poly(oxypropylene) deamine, Mineral Clay and Lithium Perchlorate”, Polymer 2002, 43, 5011.

3. Chen, Hsien Wei; Jiang, Chang Hung; Chiu, Chun Yi; Wu, Hew Der; Chang, Feng Chih “Hydrogen Bonding Effect on the Poly(ethylene oxide), Phenolic Resin, and Lithium Perchlorate-Based Solid-State Electrolyte”, Journal of Applied Polymer Science 2004, 91, 1207.

4. Chiu, Chun Yi; Chen, Hsien Wei; Kuo, Shiao Wei; Chang, Feng Chih

“Investigating the Effect of Miscibility on the Ionic Conductivity of LiClO4/PEO/PCL Ternary Blends”, Macromolecules 2004, 37, 8424.

5. Chiu, Chun Yi; Hsu, Wen Ho; Yen, Ying Jie; Kuo, Shiao Wei; Chang, Feng Chih

“Miscibility Behavior and Interaction Mechanism of Polymer Electrolytes Comprising of LiClO4 and MPEG-block-PCL Copolymers”, Macromolecules 2005, 38, 6640.

6. Chiu, Chun Yi; Yen, Ying Jie; Chang, Feng Chih “Studying the Effect of Complicated Interaction on the Phase Behavior and Ionic Conductivity of PVP-co-PMMA-Based Polymer Electrolytes”, in modified.

7. Yen, Ying Jie; Chiu, Chun Yi; Chang, Feng Chih “Specific Interaction and Miscibility Behavior in Blends of Octa-Phenol-Polyhedraloligomeric silsesquioxane (POSS) with PVP-co-PMMA Copolymers”, in preparation.

Introduction to the Author

English Name: Chiu, Chun Yi Chinese Name: 邱俊毅 Birthday: 1978, 10, 07

Address: 412 台中縣大里市東榮路一段 5 號 E-mail: [email protected]

Education:

1997, 09 ~ 2001, 06 B.S., Department of Applied Chemistry, National Chaio Tung University, Hsinchu, Taiwan, ROC.

2001, 09 ~ 2002, 06 M.S., Institute of Applied Chemistry, National Chaio Tung University, Hsinchu, Taiwan, ROC.

2002, 09 ~ 2005, 09 Ph.D., Institute of Applied Chemistry, National Chaio Tung University, Hsinchu, Taiwan, ROC.