Sulfonated penta-block ionomer (SBI) solvent cast film's ion domain spatial arrangement transitioned from random into well-connected lamellar/hexagonal structures. This micro-phase separated morphology was tunable and associated solution properties transitioning from nonpolar cyclohexane/heptane (CH) to polar tetrahydrofuran (THF). The observed morphology changes were characterized using transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS). SAXS revealed that average sulfonated inter-domain spacing increased asymmetrically within the film. For example, solvent cast SBI-H+ film inter-domain spacing changed from 30.8 nm using CH to 43 nm with THF. This lamellar/hexagonal morphology led to a two-fold water uptake increase from 23 wt% to 46 wt%, and an order-of-magnitude proton conductivity improvement from 4.5 mS/cm to 47.8 mS/cm. Ionomeric polymer-metal composite (IPMC) actuation performance was morphology dependent. The film with a random morphology had small actuation displacement with slow bending speed. However, well-connected ion domains enabled rapid and large bending motions.
- Block ionomer morphology
- Ionic/ionomeric polymer-metal composite
- Water uptake and ion conductivity
ASJC Scopus subject areas
- Organic Chemistry
- Polymers and Plastics
- Materials Chemistry