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Development of solid polymer electrolytes of polyurethane and polyether-modified polysiloxane blends with lithium salts

Wang, Shanshan
http://rave.ohiolink.edu/etdc/view?acc_num=akron1196139638

Abstract Details

2007, Doctor of Philosophy, University of Akron, Polymer Engineering.
Novel flexible solid polymer electrolytes with both high ionic conductivity and good dimensional stability based on thermoplastic polyurethane (TPU)/polyether-modified polysiloxane (PEMPS) electrolytes with various lithium salts were developed. The salts used include lithium chloride (LiCl), lithium perchlorate (LiClO4), lithium bistrifluoromethanesulfonimidate (LiN(SO2CF3)2 [LITFSI] ). These polymer electrolytes were prepared by a solvent-free, in-situ process, instead of the conventional solution casting method. In this process, the monomer, polytetramethylene glycol (PTMG), was the solvent for dissolving lithium salts instead of a highly volatile one. This process included two steps: (a) dissolve lithium salts in PTMG and PEMPS; and (b) add 4,4’-diphenylmethane diisocyanate (MDI), 1,4 butane diol (BDO) to start polymerization of polyurethane. The dissolution of salts in PTMG and PEMPS, the interaction of salt with PTMG and PEMPS, and the miscibility of PTMG/PEMPS were characterized using differential scanning calorimetry (DSC), fourier transform infrared spectroscopy (FTIR), and optical microscopy. The structure of the anion greatly affected the solubility of salts in PTMG and PEMPS. Salts with large anions, such as ClO4- and TFSI-, exhibited better solubility than ones with small anions, such as Cl-. Salts enhanced the compatibility between PEMPS and PTMG. Kinetics studies of polyurethane polymerization using the isothermal calorimetry indicated that the lithium salt slightly retarded the polymerization of TPU due to interaction of lithium ions with hydroxyl groups. Thermogravimetric analysis (TGA) characterization and tensile testing of TPU/PEMPS electrolytes demonstrated good thermal and dimensional stability. Morphological studies of TPU and TPU/PEMPS electrolytes were conducted using optical microscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM). TPU/PEMPS electrolytes exhibit a multiphase morphology with PEMPS dispersed in the TPU matrix. Salt improved compatibility between phases. FTIR studies indicated that lithium salts interacted strongly with the soft and hard segments of TPU as well as the PEMPS. Salt compatibilized these phases. The effects of PEMPS and lithium salts on Tm and the degree of crystallinity of TPU also were investigated by DSC. Ionic conductivity and its temperature dependence of these electrolytes were determined using an LCR meter. A mechanism of ionic conductivity of TPU/PEMPS electrolytes was proposed. Effects of the structure of the anion, salt–polymer interaction, and multiphase morphology on the ionic conductivity were considered.
Kyonsuku Min (Advisor)
382 p.
polymer electrolytes; polyurethane; ionic conductivity; polyether-modified polysiloxane

Recommended Citations

Citations

  • Wang, S. (2007). Development of solid polymer electrolytes of polyurethane and polyether-modified polysiloxane blends with lithium salts [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1196139638

    APA Style (7th edition)

  • Wang, Shanshan. Development of solid polymer electrolytes of polyurethane and polyether-modified polysiloxane blends with lithium salts. 2007. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1196139638.

    MLA Style (8th edition)

  • Wang, Shanshan. "Development of solid polymer electrolytes of polyurethane and polyether-modified polysiloxane blends with lithium salts." Doctoral dissertation, University of Akron, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=akron1196139638

    Chicago Manual of Style (17th edition)

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This open access ETD is published by University of Akron and OhioLINK.