Research On Laccase-catalyzed Chromogenic Polymerization Of Phenol Substrates

Laccases are multicopper oxidoreductases which are capable of forming phenoxyradicals for phenolic compounds to polymerization. Laccase-catalyzed polymerization andfiber dyeing were combined in this work, which makes it is possible to prepare polymeric dyeand dye fibers at the same time, thus a novel biological dyeing method was proposed.Enzymatic polymerization of phenols (catechol, resorcinol and hydroquinone) wascarried out using laccase. The mechanism of polymerization and the structure of the polymerswere evaluated in terms of UV-visible and Fourier transforms infrared (FT-IR) spectra. Themolecular weights of the produced polyphenols were determined with GPC. The resultsshowed that the polymerization of phenols based on laccase-catalyzed can be divided into twostages: in the first stage, the phenolic monomers turned into quinone intermediates by laccasecatalysis; in the second stage, the intermediates formed covalent bonds involvingpolymerization through further oxidization. In the structure of the produced polymers,monomer units linked together with covalent (catechol units were linked together with etherbond, resorcinol and hydroquinone units were linked together with C-C bonds, respectively).The number average molecular weights of the polyphenols ranged from1000to1400Da(corresponding to the degree of polymerization varied from10to12) with a very narrowpolydispersity value of about1.10, showing selective polymerization of phenols catalyzed bylaccase.The polyphenols produced in laccase system were applied to the fabric dyeing in thiswork. The fabric was dyed with three methods, different factors influence on the K/S valueand color fastness were evaluated, which contains the temperature, time, pH and mordant.Experiment results showed that all three methods of dyeing can be obtained excellent rubbingfastness, and the color change of washing fastness is grade3-4, the washing fastness would beimproved by increasing the dyeing temperature. After a comprehensive consideration,one-step method which performed at50℃and pH5for5h is the better choice for thebiological dyeing which based on laccase-catalyzed polymerization. Comparison of threekinds of fabric dyeing effect, linen has better color depth and fastness owe to its ligninstructure which can be catalyzed by laccase. The fabric mordanted with different metal ionsshowed different color indicating that mordant is a great way to create more color.