Title : Synthesis of comb type fluorine containing siloxane polymers and solid polymer electrolyte membranes on their basis
Energy conversion and energy storage are becoming more and more important in today’s society due to the increased demand for stationary and mobile power. In particular, electrochemical energy conversion and storage devices using battery technologies have recently attracted attention worldwide in terms of technology development and commercialization.
For example, lithium-ion batteries have been considered one of the most promising energy con¬version and storage devices due to their intrinsic advantages such as high energy density, high efficiency, superior rate capability, and long cycling life compared with other batteries.
It is well known that polysiloxanes are characterized with very low glass temperatures such as Tg = -123oC for polydimethylsiloxane, very high free volume and high segmental mobility and present best matrix for Li-ion transportation. The high solubility of the corresponding salt in the polymer is another one factor for achievement of high ion-conductivity. This condition is created by introduction to the polymer-electrolyte main chain or side group of such „host“donor group, as ester oxygen imide group, halogen, especially fluorine groups. Formation of the grid like structures increases the mechanical properties of polymer-electrolytes. Among organosilicon compounds, the combtype polymers with donor fragments at silicon atoms are of interest.
The aim of presented work is synthesis of D4 R type methyltetrafluoroorganocyclo¬tetrasiloxane with 184.108.40.206-tetra¬fluoropropyl propionate side group at silicon atoms, via hydrosilylation reaction of 220.127.116.11-tetrahydro18.104.22.168-tetramethylcyclotetrasiloxane (D4 H) with 22.214.171.124-tetrafluoropropyl acrylate in the presence of platinum catalysts at 80-900C temperature. Determination of structure and composition of obtained addition adduct is carried out by FTIR and 1 H, 13C, and 29Si NMR spectroscopy. The polymerization reaction of D4 R type methyltetrafluoroorganocyclotetrasiloxane in the presence of anhydrous powder-like Potassium hydroxide and tetramethylammonium fluoride, at 90-100oC temperature has been studied. The structure, composition and properties of obtained comb-type polymers was de¬termined using DSC, GPC, WAX, SEM, FTIR and NMR spectral methods of analysis.
Via Sol-gel reaction of hydroxyl terminated comb-type polymers and tetraethoxysilane doped with 5-20 mas.% Lithium salts, lithium triflate or Lithium bis(trifluoromethanesulfonyl)imide, transparent solid polymer electrolyte membranes is obtained.
By electrical impedance spectroscopy the ion conductivity of solid polymer electrolyte membranes is determined and the ionic conductivity of solid polymer electrolyte membranes at 25oC changes in the range 1.2x10-6 - 6.2x10-8 Siem¬ens/ cm.
Acknowledgments: The financial support of the Georgian National Science Foundation and Technology Centre in Ukraine, STCU-2016-16 (6301), is gratefully acknowledged.
Audience Take Away:
- By us will be first presented the synthesis of new type fluorine containing organocyclotetrasiloxanes; investigation polymerization reactions of organocyclotetrasiloxanes in the presence of various catalysts; investigation of sol-gel reactions of obtained comb-type polymers with regular arrangement of side groups; obtaining solid polymer electrolyte membranes on the base of Lithium salt: Lithium triflate and Lithium bis(trifluoromethanesulfonyl) imide and investigation of their ion-conductivity.
- For obtaining of comb-type polymers with regular arrangement of electro donor side groups they will use suggested by us this method.
- This suggested way of synthesis of comb-type polymers with regular structure for obtaining of solid PE membranes will be used by another researcher in their research and teaching, which will be make their research more efficient, informative and interesting.