Plasma-induced formation

The plasma treatment of a yarn of polymer fibers used for composite reinforcement provides a typical example of the improvement in adherence [78]. The result is an increase in the strength of the final composite, due to the plasma-induced formation of a very thin interphase layer between the fiber and the composite matrix, causing in turn an improved bonding between the two components (see Figure 1.10). 

Z. Li, W.M. Tong, W.F. Stickle, D.L. Neiman, R.S. Williams, L.L. Hunter, A.A. Talin, D. Li, S.R.J. Brueck, Plasma-induced formation of Ag nanodots for ultra-high-enhancement surface-enhanced Raman scattering substrates. Langmuir 23, 5135 (2007)... 

Haslekas C, Breen K, Pedersen KW et al. The inhibitory effect of ErbB2 on epidermal growth factor-induced formation of clathrin-coated pits correlates with retention of epidermal growth factor receptor-ErbB2 oligomeric complexes at the plasma membrane. Mol Biol Cell 2005 16 5832-5842. 

In the absence of Ca2+e, a-LTX only binds to LPH1 and PTPc. Ca2+-independent exocytosis requires the presence of Mg2+ and toxin insertion into the plasma membrane, but these conditions also induce formation of a-LTX channels. Influx of Na+ and efflux of K+ through these channels and associated efflux of small molecules and influx/efflux of water may cause secretion. In addition, transmitter release can be caused by membrane perturbation or direct interaction with secretory machinery. Some secretion may be nonvesicular. Receptor-mediated signaling can cause the activation of PKC in some cells. However, Ca2+-independent release is blocked by La3+, indicating that toxin pores play a crucial role in this release. 

Fig.7 Blood compatibility of PEU surfaces modified by MPEO-derived SMAs. A Simplified cascade model for material-induced blood coagulation highlighting three clotting pathways plasma fibrin formation, platelet aggregation, and hemolysis-inflammation, respectively characterized by B-C...

After a long reaction time, polymers with exceptionally high molecular weight can be synthesized by plasma-induced polymerization. Since only brief contact with luminous gas phase is involved, plasma-induced polymerization is not considered to be LCVD. However, it is important to recognize that the luminous gas phase can produce chemically reactive species that trigger conventional free radical addition polymerization. This mode of material formation could occur in LCVD depending on the processing conditions of LCVD, e.g., if the substrate surface is cooled to the extent that causes the condensation of monomer vapor. 

Certain viruses and bacterial toxins are endocytosed by a specialized pathway that involves invaginations of the plasma membrane known as caveolae. Recent studies have traced out this caveolar endocytic pathway by jointly tagging the cellular machinery with GFP and labeling viruses or bacterial toxins with fluorescent dyes, which enables their dual visualization in real time (23, 24). Such work has revealed several unanticipated properties of this pathway, such as the ability of viruses to induce formation of actin comets that propel virus-containing vesicles (23) and the stable, immobile nature of the caveolar coat that encases these vesicles (24). 

The polymer formation and properties of polymers formed by glow discharge polymerization are controlled by the balance among plasma-induced-polymerization, plasma state polymerization, and ablation. 

Because polymer formation can proceed through more than one major type of reaction, i. e., plasma-induced polymerization and plasma state polymerization, depending on the chemical structure of the monomer and also on the conditions of discharge, such as discharge wattage, flow rate, type of discharge, and geometrical factors of the reactor, the balance between polymer formation (polymerization) and ablation is for most cases extremely complicated. 

The monomer chosen is hexafluoroethane, which cannot be polymerized by plasma-induced polymerization and which cannot be polymerized in a glow discharge imder ordinary conditions presumably because the ablation process associated with the glow discharge is excessive. Attempts have been made to supress the ablation process and to shift the balance between plasma state polymerization, which is assumed to be present, and ablation. However, it has been observed that polymer formation for hexafluoroethane does occur when polyethylene is used as substrate. On the other hand, no polymer formation can be observed either with ESCA or by surface energy analysis when glass is used as a substrate. 

This indicates that ablation is no loiter dominant, and polymer formation prevails. This phenomenon can be explained by postulating that Hg reacts with F atoms emanating from the fluorine containing compound in the glow discharge and forms the more stable HF, which reduces the ablation in a dramatic manner. Because hexafluoroethane does not form a polymer by plasma-induced polymerization, the overall effect can be explained by the balance between plasma state polymerization and ablation. 

Weak discharges are also being used in order to promote polymerization of hydrocarbons and halocarbons. The plasma polymerization proceeds via a chain reaction, initiation of which occurs by electron impact induced formation of free radicals. This subject has recently been summarized in several excellent review articles 152,164-166) reader is referred to them for further information. 

Fire-retardant treatment Hammability of acrylic textiles can be reduced by using (meth)acrylates containing phosphorus monomers known to be effective as flame-retardant compounds (Price et al., 2002). Tsafack et al. (2004) smdied the plasma-grafted thin layer of phosphorus polymer by plasma-induced graft-polymerization. The formation of a characteristic protective char layer during the burning test was observed for the treated compounds whereas the untreated ones burned without residuals (Tsafack et al., 2004). 

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