Novel one-step synthesis of solid-state carbonized polymer dots by heating at around melting point of polyethylene terephthalate (PET) bottle plastic waste

Abstract

Production of luminescent carbonized polymer dots (CPDs) in the solid state has been a crucial challenge due to their tendency to self-aggregate, leading to fluorescence quenching and limiting their applicability in the solid state. In this work, we present an environmentally friendly method for producing solid-state CPDs with high photoluminescence (PL) intensity by simple one-step heating method using waste PET bottle plastic as the raw material. Based on the PET thermal analysis, heating temperatures between 200 °C and 300 °C and heating duration were explored. Through systematic experimentation, we discovered that heating temperature and time play a crucial role in controlling PL intensity, ultraviolet–visible (UV–Vis) absorption, carbonization degree, and structure of CPDs. The carbonization of CPDs occurs when the heating temperature exceeds the PET melting point, resulting in strong PL characteristics in the range of 400 and 600 nm. However, when the temperature rises, the PL decreases as the number of oxygen-containing functional groups on the surface of CPDs increases. The optimal conditions for high PL intensity were 260 °C for 2.5 h. Our one-step heating approach provides a cost-effective solution for recycling PET waste, offering promising potential for various applications.