Stable cage for photocatalyst in plastics enables conversion of low density polyethylene to photodegradable plastics with visualizable stable stage

Converting conventional plastics into photodegradable plastics using photocatalysts as additives shows promise to develop degradable plastics sustainably and efficiently. However, inhibiting the degradation performance of the photocatalyst visually during usage of plastics remains challenging. We propose constructing a photocatalyst with a visualizable stable stage by using a complex of I^-/I₂, α-cyclodextrin, and hydroxyethyl cellulose as the stable cage to modify TiO₂. The stable cage possessing blue color inhibits the photocatalytic performance under illumination forming stable stage. After specific illumination periods, the stable cage changes to white and the photocatalytic performance starts. The photocatalyst is then added to low density polyethylene forming photodegradable plastics with a visualizable stable stage. The complex consumes photogenerated electrons and holes via I₅^-/I₃^- interconversion. During illumination, the evolution of the complex's band energy is crucial for controlling photocatalytic performance. This work paves the way to converting 99 % of plastics in the market into usable photodegradable plastics.