Rapid Realization of Multicolor Room Temperature Phosphorescence of Carbon Dot-Based Composites on Natural Polymer Matrix Platforms

Multicolor room temperature phosphorescence (RTP) carbon dots (CDs) have great application potential in the field of information security encryption, but rapidly realizing multicolor RTP (including long-wavelength RTP) based on natural polymer matrices still has certain challenges. In this work, we reported for the first time that CD-based multicolor RTP composites were composed of two kinds of CDs with different fluorescence (blue and red) synthesized by a microwave solid-phase reaction method and two natural polymer matrixes, carboxymethyl starch sodium (CMSNa) and carboxymethyl chitosan (CMCS), achieved red, orange, yellow, and green RTP emission with lifetimes of 314, 264, 311, and 312 ms, respectively. In the preparation process, the synthesis of CDs and the synthesis of the CMSNa and CMCS matrixes are very simple and fast. In particular, the preparation of natural polymer matrix materials can be completed within 5 min. A series of characterizations and analyses show that the formation of strong hydrogen bond networks with different strengths promotes the multicolor RTP emission of composites based on different CDs. The two different fluorescent CDs and four different RTP composite materials show great application potential in the field of information security.