Study Data from University of Warwick Provide New Insights into Chalcogens [A Solid-State Nuclear Magnetic Resonance Study of Post-Plasma Reactions in Organosilicone Microwave Plasma-Enhanced Chemical Vapor Deposition (PECVD) Coatings]
By a News Reporter-Staff News Editor at Life Science Weekly -- New research on Chalcogens is the subject of a report. According to news reporting originating in Coventry, United Kingdom, by NewsRx journalists, research stated, "Plasma-polymerized organosilicone coatings can be used to impart abrasion resistance and barrier properties to plastic substrates such as polycarbonate. Coating rates suitable for industrial-scale deposition, up to 100 nm/s, can be achieved through the use of microwave plasma-enhanced chemical vapor deposition (PECVD), with optimal process vapors such as tetramethyldisiloxane (TMDSO) and oxygen."
The news reporters obtained a quote from the research from the University of Warwick, "However, it has been found that under certain deposition conditions, such coatings are subject to post-plasma changes; crazing or cracking can occur anytime from days to months after deposition. To understand the cause of the crazing and its dependence on processing plasma parameters, the effects of post-plasma reactions on the chemical bonding structure of coatings deposited with varying TMDSO-to-O-2 ratios was studied with Si-29 and C-13 solid-state magic angle spinning nuclear magnetic resonance (MAS NMR) using both single-pulse and cross-polarization techniques. The coatings showed complex chemical compositions significantly altered from the parent monomer. Si-29 MAS NMR spectra revealed four main groups of resonance lines, which correspond to four siloxane moieties (i.e.; mono (M), di (D), tri (T), and quaternary (Q)) and how they are bound to oxygen. Quantitative measurements showed that the ratio of TMDSO to oxygen could shift the chemical structure of the coating from 39% to 55% in Q-type bonds and from 28% to 16% for D-type bonds. Post-plasma reactions were found to produce changes in relative intensities of Si-29 resonance lines. The NMR data were complemented by Fourier transform infrared (FTIR) spectroscopy. Together, these techniques have shown that the bonding environment of Si is drastically altered by varying the TMDSO-to-O-2 ratio during PECVD, and that post-plasma reactions increase the cross-link density of the silicon oxygen network. It appears that Si H and Si OH chemical groups are the most susceptible to post-plasma reactions. Coatings produced at a low TMDSO-to-oxygen ratio had little to no singly substituted moieties, displayed a highly cross-linked structure, and showed less post-plasma reactions."
According to the news reporters, the research concluded: "However, these chemically more stable coatings are less compatible mechanically with plastic substrates, because of their high stiffness."
For more information on this research see: A Solid-State Nuclear Magnetic Resonance Study of Post-Plasma Reactions in Organosilicone Microwave Plasma-Enhanced Chemical Vapor Deposition (PECVD) Coatings. ACS Applied Materials & Interfaces, 2014;6(11):8353-8362. ACS Applied Materials & Interfaces can be contacted at: Amer Chemical Soc, 1155 16TH St, NW, Washington, DC 20036, USA. (American Chemical Society - www.acs.org; ACS Applied Materials & Interfaces - www.pubs.acs.org/journal/aamick)
Our news correspondents report that additional information may be obtained by contacting C.J. Hall, University of Warwick, Dept. of Phys, Coventry CV4 7AL, W Midlands, United Kingdom. Additional authors for this research include T. Ponnusamy, P.J. Murphy, M. Lindberg, O.N. Antzutkin and H.J. Griesser (see also Chalcogens).
Keywords for this news article include: Europe, Coventry, Chalcogens, United Kingdom, Nanotechnology, Emerging Technologies, Chemical Vapor Deposition
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