Colorimetric transition pathway mapping in polydiacetylene by hyperspectral microscopy

Abstract

The structural variance of polydiacetylene (PDA) at the nanoscale even under the same fabrication conditions is one of the origins of its poor reproducibility in chemo/biosensing. In this work, we present a spatial map of such structural distributions within a single crystal by taking an advantage of the recent development of hyperspectral microscopy in visible wavelength. Hyperspectral microscopy provides the distribution of absorption spectra at the spatial resolution of the standard optical microscopy. By track-ing the blue-to-red transition via this technique, we found that the heat application leaves a fingerprint in the transition pathways.

Dual nano-friction force microscopy/fluorescence microscopy imaging reveals the enhanced force sensitivity of polydiacetylene by pH and NaCl

“…the hydrogen bonding in the headgroup 14 , the van der Waals attraction forces between the alkyl chains 15 ) favor planarization, whereas the others (e.g. the electrostatic repulsion in the headgroups 16 , the entropy 17 ) encourage the de-planarization or the twist. For example, the shortening of alkyl chain adjacent to the acidic headgroup causes a marked increase in the thermochromic transition temperature, whereas a reduction of the alkyl tail results in the opposite effect in thermochromism attributed to the reduction of alkylalkyl interaction 18 .…”