ISMSM Image(s) of the Month!

On left, graph with two lines: one red and decreasing, one black and increasing, both near linear. On right, models of HOMO and LUMO orbitals.

Rameswar Bhattacharjee and Miklos Kertesz have discovered a continuous topological transition in ethynyl-linked acene π-conjugated polymers. The work was reported in Chemistry of Materials.
The topological transition for ethynyl-linked acene π-conjugated polymers has been described as occurring between two difference chemical compositions [Cirera, B. et al. Tailoring topological order and π- conjugation to engineer quasi-metallic polymers. Nat. Nanotechnol. 2020, 15 (6), 437−443.], which therefore is not really a transition in the usual sense. However, as a function of the continuous variable of mechanical strain along the polymer chain, Bhattacharjee and Kertesz have shown that at a critical strain value the system undergoes a topological transition from a trivial phase (Zak number = 0) to a non-trivial phase (Zak number = 1), the latter displaying localized spin states at the termini of the polymer chain. The figure below shows the behavior of the bandgap (in red) as a function of strain (ε), and on the right, the level crossing that accompanies this transition. The underlying mechanism is tied to the change of the bond length alternation (BLA, in black) along the polymer chain.

Upcoming Events

All Upcoming Events

View our most recent ISMSM Story!

Institute for Soft Matter News

Celebrating ISM Day 2023

September 26th, 2023

Researchers from ISM and affiliates gathered to discuss current research and future opportunities. …

Graphic with yellow arrow demonstrating dielectric continuum and structures of the different ion-pair complexes mentioned

Recent Research from Prof. Weiss

July 20th, 2023

A recent publication from ISM members investigating the dependence of proton transfer in ionomers on the dielectric constant of the solvent. …