A lipase from Thermomyces lanuginosus and cutinases from Thermobifida fusca and Fusarium solani hydrolysed poly(ethylene terephthalate) (PET) fabrics and films and bis(benzoyloxyethyl) terephthalate (3PET) endo-wise as shown by MALDI-Tof-MS, LC-UVD/MS, cationic dyeing and XPS analysis. Due to interfacial activation of the lipase in the presence of Triton X-100, a seven-fold increase of hydrolysis products released from 3PET was measured. In the presence of the plasticizer N,N-diethyl-2-phenylacetamide (DEPA), increased hydrolysis rates of semi-crystalline PET films and fabrics were measured both for lipase and cutinase. The formation of novel polar groups resulted in enhanced dye ability with additional increase in colour depth by 130% and 300% for cutinase and lipase, respectively, in the presence of plasticizer.

Alkaline and enzymatic hydrolyzes of poly(ethylene terephthalate) fabrics (PET) were mechanistically compared based on released degradation products (HPLC‐UV‐RI) and changes in surface properties [hydrophilicity, cationic dyeing, X‐ray photoelectron spectroscopy (XPS)]. Enzymatic hydrolysis led to an increase in the amount of hydroxyl and carboxyl groups on the surface resulting in an enhanced water absorption and dyeability. Enzymes partially adsorbed to PET fabrics during hydrolysis were completely removed by subsequent extraction according to XPS analysis. In contrast to the enzyme treatment, alkaline hydrolysis did not lead to an increase of hydroxyl and acid groups according to XPS while both treatments caused a substantial increase in hydrophilicity and were more effective on amorphous fibers. Alkaline hydrolysis led to a greater increase in the K/S value after cationic dyeing due to enlarged surface area. Consequently, ESEM‐images demonstrated that alkaline treatment drastically affected the surface morphology of the polymer resulting in crater‐like structures of the fibers, whereas after enzymatic treatment the morphology of the fibers remained unchanged. To reach similar benefits in hydrophilicity, drastically higher amounts of degradation products were released during alkaline hydrolysis as also indicated by >6% weight loss compared to <1% after enzyme treatment. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6435–6443, 2008

Recently the potential of enzymes for surface hydrophilisation and/or functionalisation of polyethyleneterephthalate (PET) and polyamide (PA) has been discovered. However, there was no correlation between enzyme class/activity (e.g. esterase, lipase, cutinase) and surface hydrolysis of these polymers and consequently no simple assay to estimate this capability. Enzymes active on the model substrates bis (benzoyloxyethyl) terephthalate and adipic acid bishexyl-amide, were also capable of increasing the hydrophilicity of PET and PA. When dosed at the identical activity on 4-nitrophenyl butyrate, only enzymes from Thermobifida fusca, Aspergillus sp., Beauveria sp. and commercial enzymes (TEXAZYME PES sp5 and Lipase PS) increased the hydrophilicity of PET fibres while other esterases and lipases did not show any effect. Activity on PET correlated with the activity on the model substrate. Hydrophilicity of fibres was greatly improved based on increases in rising height of up to 4.3 cm and the relative decrease of water absorption time between control and sample of the water was up to 76%. Similarly, enzymes increasing the hydrophilicity of PA fibres such as from Nocardia sp., Beauveria sp. and F. solani hydrolysed the model substrate; however, there was no common enzyme activity (e.g. protease, esterase, amidase) which could be attributed to all these enzymes.