Give it the plasma treatment: strong adhesion without adhesives
by Staff Writers
Osaka, Japan (SPX) Dec 27, 2018
Polymers containing plastics are essential in modern life. Being lightweight, strong and unreactive, a vast range of technologies depend on them. However, most polymers do not adhere naturally to other materials, so they need adhesives or corrosive chemical treatments to be attached to other materials. This is a problem in areas like food and medicine, where contamination must be avoided at all costs.
A clean way to make industrial polymers adhesive is urgently needed. Now, a team at Osaka University has achieved just that. They have developed a suite of plasma treatments to allow vulcanized rubber and the plastic PTFE (polytetrafluoroethylene) to adhere to one another, or to other materials. The method activates the polymers' surface chemistry, as described in a study in Scientific Reports.
"If you spray PTFE with a plasma of helium at 200 degrees, it can adhere to unvulcanized rubber - this is a technique we developed earlier in our lab," says study lead author Yuji Ohkubo. "But vulcanized rubber presents a greater challenge. In our latest study, we customized a new plasma treatment for vulcanized silicone rubber, making it adhere strongly to PTFE for the first time."
The silicone in question was PDMS (polydimethylsiloxane), a well-known resin. While the key breakthrough in PTFE adhesion was the heat-assisted plasma treatment, the trick with PDMS is to bombard the surface with a plasma jet, by forcing nitrogen/air plasma through a small hole. The jet breaks the silicon-carbon bonds on the surface and converts them to silanol (Si-OH).
Being more reactive than the original silicone surface, these silanol groups can bond with PTFE. Under high pressure, hydrogen bonds form between silanol and the oxygen-containing functional groups on the treated PTFE. Strong covalent bonds (C-O-Si, where C comes from PTFE and Si from silicone) further stitch the two polymers together, even with no adhesive.
Uniting the two materials allows each to enjoy the benefits of the other - the chemical resistance, dirt-repellent and slide-ability of PTFE, and the elasticity of silicone. Opaque PTFE can also be replaced by PFA (perfluoroalkoxy alkane) if transparency is needed. And that's not all - when the reverse side of the PDMS is also plasma-jetted, it can bond to copper and even glass. Like an extremely strong double-sided tape, this three-layer sandwich allows the fluoropolymers to adhere cleanly to other useful materials.
"PDMS is widely used in medicine, for example in microfluidic chips," explains co-author Katsuyoshi Endo. "There could be huge benefits in making both PTFE and PDMS more versatile for medical and food technologies through adhesive-free adhesion. Combined with the lack of any need for volatile chemicals, we hope our method will broaden the horizons for polymers in high technology."
Sustainable 'plastics' are on the horizon
Tel Aviv, Israel (SPX) Dec 27, 2018
A new Tel Aviv University study describes a process to make bioplastic polymers that don't require land or fresh water - resources that are scarce in much of the world. The polymer is derived from microorganisms that feed on seaweed. It is biodegradable, produces zero toxic waste and recycles into organic waste. The invention was the fruit of a multidisciplinary collaboration between Dr. Alexander Golberg of TAU's Porter School of Environmental and Earth Sciences and Prof. Michael Gozin of TAU's S ... read more
|The content herein, unless otherwise known to be public domain, are Copyright 1995-2024 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. General Data Protection Regulation (GDPR) Statement Our advertisers use various cookies and the like to deliver the best ad banner available at one time. All network advertising suppliers have GDPR policies (Legitimate Interest) that conform with EU regulations for data collection. By using our websites you consent to cookie based advertising. If you do not agree with this then you must stop using the websites from May 25, 2018. Privacy Statement. Additional information can be found here at About Us.