Synthesis of Janus Polydiacetylene Sensor Particles with Thermochromism and Solvatochromism Properties

Abstract

The first report is presented on the fabrication of anisotropic Janus polydiacetylene (PDA) microparticles with dual colorimetric properties. Spherical proto-PDA particles are initially created by drying an emulsion containing 10,12-pentacosadiynoic acid (PCDA) monomers, followed by UV polymerization. By heating an aqueous dispersion of these PDA particles, the unpolymerized PCDA within the PDA particles is liquefied, inducing partial phase separation and eventually leading to the formation of a Janus morphology composed of proto-PDA and deriv-PDA bulbs. Notably, each bulb of the Janus particles undergoes a blue-to-red transition under thermal stress during the Janus formation process, with subsequent UV irradiation triggering a reversible red-to-blue transition. This reversibility is attributed to the formation of new self-assembled PCDA domains from residual PCDA monomers within the particles. Interestingly, each bulb of the Janus PDA particles exhibits distinct solvatochromic properties. These findings suggest significant potential for Janus PDA particles in advanced sensing technologies, particularly as solvent sensors with enhanced sensitivity and an expanded detection range.