Polyrhodanine coated cellulose nanocrystals as optical pH indicators

A simple and green approach to produce cellulose nanocrystal@polyrhodanine (CNC@PR) core-shell nano-particles via in situ polymerization is proposed. The core-shell nanoparticles displayed reversible colour change in response to pH, confirming their utility as optical pH indicators. This property was retained when the nanoparticles were configured into other shapes, such as flat films or hydrogel beads.