Author(s)

Kewen Fu^1,2, Jian Li^1,2, Dongkai Qin^1,2, Luwei Shi^1,2, Xiangyu Ni^1,2, Kaikai Zhao^1,2, Dequan Xu^2,3*, Ailin Yuan^1,2, Chunling Zheng^1,2*

¹College of Food Science and Light Industry, Nanjing Tech University, Nanjing, China.
²Institute of Textile Auxiliary and Ecological Dyeing Finishing, Nanjing Tech University, Nanjing, China.
³College of Chemistry and Chemical Engineering, Wuhan Textile University, Wuhan, China.

The dyeing temperature of natural dye lac red on two kinds of natural protein fibers was studied, and the interaction between dyestuff and fiber was discussed through thermodynamic study and density functional theory (DFT) calculation. The optimum temperature for lac red dyed silk was 60˚C and wool showed a better response at 90˚C. The thermodynamics study revealed good Nernst isotherm and Freundlich adsorption models respectively, and the lac dye adsorption processes were both spontaneous and exothermic. The potential interaction of Laccaic acid A with the external environment by electrostatic potential and atomic charge distribution was first explored. With molecular simulation, Laccaic acid A and glycine composed 8 stable complexes. Then, typical hydrogen bonds, bond length, and binding energy, etc. were analyzed. The results revealed lac red on silk and wool fabric mainly depended on the weak hydrogen bonds and van der Waals force which determined the low dye fastness.

Natural Dye, Lac Red, Wool, Silk, Dyeing Thermodynamics, DFT Calculation, Wavefunction

Fu, K. , Li, J. , Qin, D. , Shi, L. , Ni, X. , Zhao, K. , Xu, D. , Yuan, A. and Zheng, C. (2022) Dyeing Thermodynamics and Supramolecular Structure of Lac Red on Protein Fibers. Journal of Textile Science and Technology, 8, 89-106. doi: 10.4236/jtst.2022.82008.