AsianScientist (Jan. 7, 2019) – In a study published in the journal Scientific Reports, scientists in Japan report a method to make industrial polymers sticky without the need for adhesives.
Being lightweight, strong and unreactive, polymers such as plastic and rubber are useful in many aspects of modern life. However, these polymers must be treated with corrosive chemicals or adhesives to help them to attach to other materials.
In the present study, researchers led by Assistant Professor Yuji Ohkubo of Osaka University, Japan, found a way to create ‘sticky’ polydimethlysiloxane (PDMS), a silicon-based polymer, and ‘sticky’ plastic polytetrafluoroethylene (PTFE) by modifying the surfaces of both materials.
PTFE was treated with plasma at 200 degrees Celsius, which revealed oxygen-containing functional groups on its surface. On the other hand, PDMS was bombarded with a plasma jet, produced by forcing nitrogen or air plasma through a small hole. The plasma jet breaks the silicon-carbon bonds on the surface and converts them to silanol.
Under high pressure, hydrogen and covalent bonds form between silanol and the oxygen-containing functional groups on the treated PTFE, thereby stitching PDMS and PTFE together even in the absence of adhesives.
The combined materials also display synergistic properties such as increased chemical resistance and better repulsion of dirt. In addition, if polymer manufacturers would like to fabricate a transparent final product, PTFE can be replaced by perfluoroalkoxy alkane.
The team further showed that when the reverse side of the PDMS is also subjected to the plasma jet treatment, it can bond to copper and even glass. Like an extremely strong double-sided tape, this three-layer sandwich allows the polymers to adhere cleanly to other useful materials.
“PDMS is widely used in medicine, for example in microfluidic chips. There could be huge benefits in making both PTFE and PDMS more versatile for medical and food technologies through adhesive-free adhesion,” said study co-author Professor Katsuyoshi Endo of Osaka University.
The article can be found at: Ohkubo et al. (2018) Adhesive-free Adhesion Between Heat-assisted Plasma-treated Fluoropolymers (PTFE, PFA) and Plasma-jet-treated Polydimethylsiloxane (PDMS) and Its Application.
Source: Osaka University.
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