(766b) Microstructure and Mechano-Electrical Property of Ultra-Stretchable Iono-Elastomer Via Small Angle Scattering and Rheology

Ionic liquids and block copolymers are two representative classes of “designer compounds”, which are known for tunability and controllability of their physical and chemical properties via careful selection of their components. Hierarchaically structured functional materials could be synthesized by self-assembly of block copolymer in ionic liquids, where block copolymer can impart mechanical strength to the material via self-assembly into long ranged ordered structure, and ionic liquid can impart electrical conductivity to the system via conmitant free mobile ions.[1] We have demonstrated a simplified two-step manufacturing process to create stretchable materials with tunable conductivity, termed “iono-elasotmer”, applicable for stretchable electronic technologies by self-assembly of concentrated solutions of end-functionalized commercially available, in-expensive triblock copolymer in a protic ionic liquid, followed by micelle corona crosslinking.[2] The resulted materials exhibit an unprecedented combination of high stretchability (elongation at break is 3000% and tensile strength at break is 200 MPa), tunable ionic conductivity and mechano-electrical response. To our knowledge, the strechability is about 10 times higher than reported elastomers. Importantly, the materials conductivity increases with extension, a unique and non-trivial material response, whose origin is postulated to be the microstructural rearrangement of the micelles under uniaxial deformation using in-situ Sentmanat extensional rheometer (SER) and small angle neutron scattering measurement.[3, 4, 5] Based on the unique material property, a strain sensor was developed for capturing range of motions. [5]

References:

[1] Chen, R.; López-Barrón, C. R.; Wagner, N. J. “Self-assembly of block copolymers in ionic liquids”. Book chapter for ACS Symposium Series: “Ionic Liquids: Current State and Future Directions”. In press.

[2] López-Barrón, C. R.; Chen, R.; Wagner, N. J.; Beltramo, P. “Self-assembly of Pluronic F127-diacrylate in ethylammonium nitrate: structure, rheology and ionic conductivity before and after photo-crosslinking”.

Macromolecules, 2016, 49(14), 5179-5189.

[3] López-Barrón, C. R.; Chen, R.; Wagner, N. J. “Ultrastretchable iono-Elastomers with mechanoelectrical Response”. ACS Macro Letter., 2016, 5, 1332-1338.

[4] López-Barrón, C. R.; Chen, R.; Wagner, N. J. Stretchable iono-elastomers with mechano-electrical response, devices incorporating iono-elastomers, and methods of making thereof. PCT/US17/26621, April 7, 2017.

[5] López-Barrón, C. R.; Chen, R.; Wagner, N. J. Cross-linked ionoelastomers with outstanding tensile responses and high ion conductivity. U.S. Patent Serial No. 62/393,133, September 12, 2016.