Vigilancia Tecnológica

The grafting of N-(4-hydroxyphenyl)-3,4,9,10-perylenetetracarboxylic-3,4-anhydride-9,10-imide (4) and N-(4-hydroxyphenyl)-1,4,5,8-naphthalenetetracarboxylic-1,8-anhydride-4,5-imide (8) onto low-molecular-weight chitosan (5) was performed. The fluorescence, stability, electroactivity, conductivity, and solubility properties of the grafted chitosan polymer 9 were highly enhanced compared to the original chitosan. The weight-average molecular weight (Mw) of 19,800 g/mol was obtained. Grafted chitosan has even more excellent thermal stability with a higher initial decomposition temperature of 285 °C and char yield at 900 °C up to 73%. The fluorescence quantum yield efficiencies for polymer 9 are very high in all studied solvents (70% in CH3CN). The polymer showed five stepwise, fast, reversible one-electron reductions in electrochemical investigations due to the conductive fluorophores 4 and 8. The HOMO/LUMO levels were calculated as ??5.56 and ??4.14 eV, corresponding to the low band gap of 1.42 eV. The spectroelectrochemistry investigations confirmed the nature of the electron transfers. The morphological characterization using AFM, SEM, and TEM methods indicated a highly crystalline character of the grafted chitosan. The modified chitosan has the potential to be applied in various organic photonics and as a significant substrate material.

Graphical abstract Grafted chitosan polymers combining high crystalline character and excellent fluorescence, electroactivity and conductivity are promising candidates for photonic applications