Molecularly Engineered Intrinsically Healable and Stretchable Conducting Polymers

Advances in stretchable electronics concern engineering of materials with strain-accommodating architectures and fabrication of nanocomposites by embedding a conductive component into an elastomer. The development of organic conductors that can intrinsically stretch and repair themselves after mechanical damage is only in the early stages yet opens unprecedented opportunities for stretchable electronics. Such functional materials would allow extended lifetimes of electronics as well as simpler processing methods for fabricating stretchable electronics. Herein, we present a unique molecular approach to intrinsically stretchable and healable conjugated polymers. The simple yet versatile synthetic procedure enables one to fine-tune the electrical and mechanical properties without disrupting the electronic properties of the conjugated polymer. The designed material is comprised of a hydrogen-bonding graft copolymer with a conjugated backbone. The morphological changes, which are affected by the composition of functional side chains, and the solvent quality of the casting solution play a crucial role in the synthesis of highly stretchable and room-temperature healable conductive electronic materials

Effects of Alkali Cations and Halide Anions on the Self-Assembly of Phosphatidylcholine in Oils

The interactions between ions and phospholipids are closely associated with the structures and functions of cell membrane. Instead of conventional aqueous systems, we systematically investigated the effects of inorganic ions on the self-assembly of lecithin, a zwitterionic phosphatidylcholine, in cyclohexane. Previous studies have shown that addition of inorganic salts with specific divalent and trivalent cations can transform lecithin organosols into organogels. In this study, we focused on the effect of monovalent alkali halides. Fourier transform infrared spectroscopy was used to demonstrate that the binding strength of the alkali cations with the phosphate of lecithin is in the order Li⁺ > Na⁺ > K⁺. More importantly, the cation–phosphate interaction is affected by the paired halide anions, and the effect follows the series I^– > Br^– > Cl^–. The salts of stronger interactions with lecithin, including LiCl, LiBr, LiI, and NaI, were found to induce cylindrical micelles sufficiently long to form organogels, while others remain organosols. A mechanism based on the charge density of ions and the enthalpy change of the ion exchange between alkali halides and lecithin headgroup is provided to explain the contrasting interactions and the effectiveness of the salts to induce organogelation