Horseradish peroxidase-catalyzed poly(ethylene glycol)-templated polymerization of gallic acid to improve the dyeing properties of silk fabrics

Due to the low fastness of natural dyed silk fabrics, their general use is restricted. Therefore, not only an eco-friendly dyeing method, but also a method of increasing the color fastness must be developed. In this paper, gallic acid was synthesized using a new approach and arranged on poly(ethylene glycol) templates using an horseradish peroxide (HRP)-catalyzed oxidative polymerization. The polymerization mechanism was investigated in detail using UV-Vis, FT-IR and HPLC-ESI-MS. The results confirmed that during the catalysis of gallic acid by HRP, the templates promoted the enzymatic polymerization in terms of the amount of poly(gallic acid) produced and the degree of polymerization. In addition, the dyeing properties and color fastness were investigated using the K/S value and AATCC fastness test, respectively. Upon analyzing the color depth, the K/S value of the silk fabric dyed using PEG as a template was significantly higher than that in absence of PEG. The silk fabric dyed in presence of PEG showed higher fastness in all color fastness tests (washing, perspiration, rubbing, water, dry cleaning and light). Moreover, the higher color depth of the poly(gallic acid)/PEG-treated silk fabrics further validated the important role of PEG as a template.