Single Particle Semi‐Reversible Solvatochromic Sensor

Abstract A semi‐reversible solvatochromic sensor is presented using polydiacetylene@polydimethylsiloxane (PDA@PDMS) core–shell particles fabricated via a co‐flow microfluidic method. Exposing these particles to specific volumes and types of solvents triggers the migration of unpolymerized 10,12‐pentacosadiynoic acid (PCDA) monomers from the PDA core to the PDMS shell, enabling distinctive semi‐reversible color‐change patterns in both regions during repeated cycles of UV exposure and solvatochromism. The solvent‐induced response of PDA@PDMS varies according to solvent permeability and solvent‐mediated PCDA transport efficiency, which are influenced by PDMS swelling, solvent boiling point, and PCDA solubility. Compared to bare PDA particles and PDA/PDMS composite particles, PDA@PDMS exhibits superior solvent differentiation through distinct solvatochromic responses across a range of solvents. These PDA@PDMS core–shell particles offer a robust platform for real‐time, precise multi‐solvent detection, with significant potential for analytical and environmental monitoring applications.