Ti and TiO2 magnetron sputtering in roll-to-roll fabrication of hybrid membranes

The large-scale surface modification of polyethylene terephthalate track-etched membranes (TM) using industrial roll-to-roll planar magnetron sputtering of Ti and TiO2 for use in advanced technologies such as separation, biotechnology, and microelectronics was investigated. The Ti and TiO2-Ti coated TM surface characterisation was done using a combination of scanning electron microscopy, atomic force microscopy, contact angle- and scratch adhesion testing. Structural characterisation was done using transmission electron microscopy, energy dispersive x-ray spectroscopy, x-ray photoelectron spectroscopy, and tensile testing. Water permeability and bubble point testing were used to confirm the membrane permeability after surface modification. A tensile test showed that the coated membranes’ strength was within an acceptable range of one another. Magnetron sputtering did not lead to significant changes in the water permeability, nor a notable reduction in the pore diameter of the resulting Ti-TM and TiO2-Ti-TM hybrid membranes. Sputtered coatings on top of the TM surface significantly reduced the water contact angle from 72° for an untreated TM to 33° and 28° for Ti-TM and TiO2-Ti-TM, respectively. This investigation shows that roll-to-roll magnetron sputtering is a viable approach to the large-scale fabrication of hybrid membranes based on TM as model support.