Copper ions reinforced flexible carboxymethylcellulose/polyethyleneimine composite films with enhanced mechanical properties, UV-shielding performance, thermal stability, solvent resistance, and antibacterial activity.

A composite film (CMC/PEI) consisting of anionic carboxymethylcellulose (CMC) and cationic polyethyleneimine (PEI) can be easily produced through the solution casting method using self-assembly based on electrostatic interaction and hydrogen bonding. Subsequently, the resulting CMC/PEI polyelectrolyte composite film with a network structure was crosslinked with divalent Cu2+ ions through ionic and coordination bonds, resulting in a strengthened Cu(II)@CMC/PEI film. The composite film was characterized based on its structural, surface, thermal, UV protection, antibacterial, and degradation aspects. The results demonstrated this film has impressive mechanical properties, remarkable solvent resistance, good antibacterial properties, and excellent UV-shielding performance by completely blocking ultraviolet light with wavelengths below 360 nm. These properties can be attributed to the presence of Cu2+ ions and PEI in the film. This work is valuable for the development of novel UV-shielding materials and should contribute to the design of carboxymethylcellulose composite films with desirable properties and exceptional performance.

Improved Singlet Oxygen Production by Synergistic Effect via a Dual-Core Photosensitizer Doped Polymer Fibrous Films: Synthesis and Performance.

Singlet oxygen (1O2) is a common reactive oxygen species that has found wide application in wastewater processing, photochemical synthesis, and photodynamic therapy. In this paper, a dual-core metal [a Re(I)-based component and a Gd(III)-based component] photosensitizer was synthesized and doped into polymer fibrous films for 1O2 generation. Here the Re(I)-based component is responsible for the photosensitizing reaction which directly transformed 3O2 to 1O2, while the Gd(III)-based component served as an auxiliary part that assisted the transformation from 3O2 to 1O2 via synergistic effect by its triplet excited ligands. The photophysical parameters of this photosensitizer (denoted as Re-Gd) and its fibrous films (denoted as Re-Gd@PVP) were carefully recorded, discussed, and compared. It was found that the excited state lifetime and photostability of Re-Gd were both improved after being doped into fibrous films, favoring 1O2 generation. The 1O2 generation performance comparison between Re-Gd in the solid state, in solution, and fibrous films suggested that 1O2 generation performance was indeed improved by the electrospinning films. In addition, the positive factor of synergistic effect on improving 1O2-producing efficiency was confirmed by comparing Re-Gd@PVP films with reference films with a single-core metal photosensitizer having no synergistic effect.