In situ synthesis of polyynes in a polymer matrix by pulsed laser ablation in liquid

TL;DR

This study demonstrates a novel in situ method for synthesizing stable polyynes within a PVA matrix using pulsed laser ablation in liquid, with potential for advanced material applications.

Contribution

It introduces a single-step PLAL process to produce stable polyynes in PVA, enhanced by Ag colloids for SERS, and shows long-term stability of polyyne nanocomposites.

Findings

Polyynes are successfully synthesized in PVA via PLAL.

Polyynes in nanocomposites remain stable for at least 11 months.

Adding Ag colloids enhances SERS detection and stability.

Abstract

Polyynes are finite chains formed by sp-hybridized carbon atoms with alternating single and triple bonds and displaying intriguing electronic and optical properties. Pulsed laser ablation in liquid (PLAL) is a well assessed technique for the physical synthesis of hydrogen-capped polyynes in solution, however, their limited stability prevents further exploitation in materials for different applications. In this work, polyynes in poly(vinyl alcohol) (PVA) were produced in a single-step PLAL process by ablating graphite directly in aqueous solution of PVA, investigating the role of polymer concentration. The presence of PVA solution, as a participating medium for PLAL, is shown to favour the formation of polyynes. The addition of Ag colloids to the aqueous PVA/polyynes solution allowed surface-enhanced Raman spectroscopy (SERS) measurements, carried out both on liquid samples and on free-standing nanocomposites, obtained after solvent evaporation. We show that polyynes in the nanocomposite remain stable at least for 11 months, whereas the corresponding PVA/Ag/polyynes solution displayed a strong polyyne reduction already after 3 weeks. These results open the view to further characterizations of the properties of polyyne-based films and materials.