The effect of ion energy upon the chemical structure of triglyme and E2OV plasma polymerised films.
Barton, David; Fraser, Stuart; Short, Robert D.; Bradley, James W.
American Physical Society, 55th Gaseous Electronic Conference,
October 15-18, 2002,
Minneapolis, MN, Meeting ID GEC02, abstract #WF1.004
Using energy resolving plasma mass spectrometry, QCM deposition rate monitoring and XPS samples, we have studied the effect of ion energy upon derived polymer film properties. The polymers are produced in a 13.56MHz RF plasma reactor, at a pressure of 50mTorr, and a generator output of 5W. The films are deposited onto a specially designed substrate, behind which are placed the diagnostics. By applying an RF bias to the substrate, which is phase and amplitude matched to the RF potentials in the plasma, we can manipulate the ion energy between set limits. These limits are the time average potential differences Vp-Vsb, down to the DC minimum of Vp-Vf. The subscripts refer to the plasma (p), self bias (sb) and floating (f) potentials respectively. An important feature of this technique is that the bulk plasma is undisturbed, so that ion energy is the only parameter under investigation. Using the monomers triglyme and E20V, chosen for their biological anti-fouling properties, we demonstrate the ability to manipulate film properties by selective control of plasma ion energies
it says it is a meeting abstract. that's not a publication i think.
The plasma polymerization of acrylic acid has been probed by means of mass spectrometry (neutrals and positively charged species) and ion energy spectroscopy. The interpretation of mass spectra is facilitated by the comparison of mass spectra obtained from plasmas of a 13C-labeled acrylic acid (with the label at the carboxyl C) and plasmas of an unlabeled acrylic acid. Mass spectrometry of the neutrals shows that under the action of plasma, even at low plasma power inputs, P, there is substantial fragmentation of the acrylic acid. Fragmentation is homolytic at the carboxyl functional group, and this is attributed to energy transfer from electrons. In the positive ion mass spectrometry, oligomers of the series (nM + H)+ as high as n = 4 were detected. Low ion energies were measured at low P and are consistent with minimal fragmentation on arrival at a self-biased surface. On the basis of these measurements, we speculate that at low P, gas-phase cationic oligomers may be responsible for up to 50% of the deposit's total mass. Grafting of “intact” acrylic acid accounts for the remaining mass, and the two processes (gas-phase oligomerization and grafting) give rise to a highly functionalized plasma polymer, containing predominately carboxyls. Irrespective of the exact weighting given to these alternative mechanisms, it is the abundance of intact acrylic acid which determines the extent of functional group retention. It follows that as P increases and the amount of intact acrylic acid declines steeply, high levels of functional group retention cannot be achieved
Fourier transform infrared spectroscopy of azide and cyanate ion pairs in AOT reverse micelles
Owrutsky, Jeffrey C.; Pomfret, Michael B.; Barton, David J.; Kidwell, David A.
Journal of Chemical Physics, Volume 129, Issue 2, pp. 024513-0245
13-10 (2008).
Evidence for ion pair formation in aqueous bis(2-ethylhexyl) sulfosuccinate (AOT) reverse micelles (RMs) was obtained from infrared spectra of azide and cyanate with Li+, Na+, K+, and NH4+ counterions. The anions' antisymmetric stretching bands near 2000 cm-1 are shifted to higher frequency (blueshifted) in LiAOT and to a lesser extent in NaAOT, but they are very similar to those in bulk water with K+ and NH4+ as the counterions. The shifts are largest for low values of wo=[water]/[AOT] and approach the bulk value with increasing wo. The blueshifts are attributed to ion pairing between the anions and the counterions. This interpretation is reinforced by the similar trend (Li+>Na+>K+) for producing contact ion pairs with the metal cations in bulk dimethyl sulfoxide (DMSO) solutions. We find no evidence of ion pairs being formed in NH4AOT RMs, whereas ammonium does form ion pairs with azide and cyanate in bulk DMSO. Studies are also reported for the anions in formamide-containing AOT RMs, in which blueshifts and ion pair formation are observed more than in the aqueous RMs. Ion pairs are preferentially formed in confined RM systems, consistent with the well established ideas that RMs exhibit reduced polarity and a disrupted hydrogen bonding network compared to bulk water and that ion-specific effects are involved in mediating the structure of species at interfaces.
WTF? You just posted two papers that have absolutely nothing to do with each other. Is there supposed to be some point here? Do you even understand what these papers are about, and what important result the authors are trying to communicate?
I guess I'll ask again, since you didn't answer my question. Is there supposed to be some point here? Do you even understand what these papers are about, and what important result the authors are trying to communicate? If there is a point, please explicitly explain it rather than hinting around about people "sharing the same water cooler".