A two-step process for surface modification of poly(ethylene terephthalate) fabrics by Ar/O2 plasma-induced facile polymerization at ambient conditions

• Surface modification of PET fabrics by APPJ polymerization was achieved.
• The DBD pretreatment increase the linking intensity of the coated polymer on PET.
• Hydrophilicity and dyeing property of modified PET fabrics were both improved.
• The APPJ modification could impart durable hydrophilicity to PET fabrics.

In this paper, a two-step process was explored for the modification of poly(ethylene terephthalate) (PET) fabrics by Ar/O2 plasma-induced polymerization with hexamethylene diamine (HMD) monomer. The first step involved a parallel-plate shape dielectric barrier discharge (DBD) apparatus to modify the PET fabrics. This treatment could introduce some polar groups onto the PET surface, and also simultaneously increased the surface roughness. Thus, this process was very helpful to increase the linking intensity between the fabric substrate and the later polymerized layer. For the second step of the process, an atmospheric pressure plasma jet (APPJ) apparatus with Ar and O2 as working gases was employed to achieve the polymerization with HMD monomer on the fabric surface. The measurement of the plasma gas temperature by infrared thermometry, and the detection of reactive species by optical emission spectroscopy were used for characterizing the polymerization process. It was found that the plasma gas temperature was not higher than 307 K when the applied power was lower than 50 W, and many reactive species (e.g.
• OH,
• H,
• O) existed in the plasma. Field emission scanning electron microscopy images showed that the surface roughness of PET increased greatly with the DBD plasma treatment, and a smooth thin film was formed under the APPJ polymerization with HMD monomer. Fourier transform infrared spectroscopy results indicated that HMD polymer was incorporated into PET fabrics through the formation of new covalent bonds. Chemical composition was analyzed by X-ray photoelectron spectroscopy, and many functional groups (e.g. C–N, O = C–NH) occurred on the PET fabric surface. Meanwhile, the dyeing property of modified PET evaluated by color yield (K/S) analysis was improved obviously.