Wawryszyn, M./ Wilhelm, R./ Kim, J./ Zhong, X./ Raymond, J.E./ Thelen, R./ Trouillet, V./ Schwotzer, M./ Bräse, S./ Kim, D.H./ Abbott, N.L./ Lahann, J. (2023)

ACS Appl. Polym. Mater. 2023, 5, 3, 1670-1680, https://doi.org/10.1021/acsapm.2c01477

Abstract

In the past decade, the phosphorescence of metal-free confined polymer structures has generated interest in optoelectronics due to their sustainability, low toxicity, and deployment in sensing applications. Herein, a free-standing array of laterally organized nanofibers was prepared via templated chemical vapor deposition polymerization into a liquid crystalline (LC) phase, and their optical properties were compared to compositionally identical films. The fibers converge into laterally aligned membranes that maintain a high internal order despite the surfaces of the membranes remaining uniform and closed. The membranes consisted of hourglass-shaped nanofibers with features in the micro- and nanometer regime. Free-standing nanofiber membranes differ from polymer films of equivalent chemical composition in several key features: (1) Anisotropic growth of polymer nanofibers with constraint and compliance to an LC template, (2) a high surface-to-volume ratio, and (3) the occurrence of a long-lived emission in the blue region, which persists for multiple seconds after excitation. This study constitutes the first report of long-lived emission from solid-state poly(p-xylylenes) nanofibers. Prospective applications of morphologically controlled polymer arrays with structural luminescence include organic sensors and optoelectronic devices.