Monomer-deficient

As shown in Figures 5.10 and 5.11, in the monomer-deficient region the value of A becomes independent of WjFM. Therefore, the normalized deposition rate for this region can be written as... 

By virtue of Eq. (5.4), the value of B is expected to be larger where M is larger however, an exact estimate of the value of B is difficult to make because of the transition region from the energy-deficient region to the monomer-deficient region. 

An interesting correlation is found, however, between the value of (WIFM)c, the critical WjFM value above which plasma polymerization can be considered in the monomer-deficient region, and the nature of the monomers. In Figure 5.15 values of (WIFM)c, are plotted against values of total bond energy divided by the molecular weight of the corresponding monomer. 

It is also important to recognize the domain in which a plasma polymerization is carried out under a given set of operational conditions. The value of WjFM alone does not identify whether a plasma polymerization is in the energy-deficient or the monomer-deficient region. A crude estimate of the domain might be made by the parameter WjFM)la( if the value of a were known for the reactor. The following conditions can be used for this purpose ... 

Based on WjFM, the material formation in LCVD can be divided into two regimes an energy-deficient regime and a monomer-deficient regime. In the energy-deficient domain, ample monomer is available but the power input rate is insufficient. In this domain, the deposition rate increases with the power input. In the monomer-deficient (power-saturated) domain, sufficient discharge power is available but the monomer feed-in rate is the determining factor for the deposition. 

The decline of deposition rate with increasing flow rate seen in Figure 8.2 is due to the fact that the increase of flow rate at a fixed W decreases the value of WjFM. In the low-IF case, the decrease of WjFM crosses the borderline of two domains, i.e., from the energy-deficient domain to the monomer-deficient domain. It is important to note that these two domains cannot be identified based simply on the value of operational parameters. The domain can be identified only by the dependence of the deposition rate on operational parameters WjFM as depicted in Figure 8.3. The critical value of WjFM at which the domain changes is dependent on the nature of organic molecules as described in Chapter 5. 

As the power input is increased (at a given flow rate), the domain of plasma polymerization approaches the monomer-deficient one, which can be recognized by the asymptotical approach of D.R. value to a horizontal line as the power input increases. In the monomer-deficient domain, the deposition rate (plateau value) increases as the flow rate is increased and shows a linear dependence on the monomer feed-in rate at a given discharge power and the system pressure (Fig. 8.2), i.e.,... 

Plasma polymerization is system dependent, and a monomer does not yield a well-defined polymer that can be identified by plasma polymerization. Plasma polymers formed at the high WjFM end of the power-deficient domain as well as in the monomer-deficient domain are tight three-dimensional amorphous networks, that do not contain discernible functional groups (type A plasma polymers). 

In plasma polymerization, the dependence of the deposition rate on the operating condition varies based on the domain of the plasma polymerization as described in Chapter 8. There are three domains energy-deficient domain, transitional domain, and monomer-deficient domain. They are classified based on the dependence of the normalized deposition rate, DjFM, on the normalized energy input parameter, WjFM, where D is the deposition rate. 

The carbon Is spectra were deconvoluted into six peaks using a nonlinear least-squares curve-fitting program. Peaks centered at 293.3, 291.2, 289.5, 288.3, 286.6, and 285.0 eV are due to CF3, CF2, CF-CF , CF, C-CF , and C, respectively. Large numbers of CF3 and CF2 groups and small numbers of C group are present in the polymer prepared in the monomer-deficient (energy-saturated) domain, and the F/C ratios are approximately 1.6. 

L-C (large reactor, center position) monomer-deficient domain for all operating conditions,... 

However, these findings are in contradiction to the generally observed trend that CF3 and CF2 are found in the deposition that is formed with short kinetic pass length, which often occurs in the energy-deficient domain. In the monomer-deficient domain, C-CF - and C-rich structures with low F/C values are obtained. These discrepancies may be explained by consideration of the following factors. 

Figure 34.21 shows a very important correlation between the deposition characteristics and the membrane performance shown as the same function of Wj FM. The deposition plot (Fig. 34.21a) typically shows three regions the power-deficient region at low values of WjFM, the monomer-deficient region at high values of WjFM, and a transition region that is intermediate between the two deficient regions as described in Chapter 8. 

Figure 35.1 depicts the dependence of the deposition rate on the discharge parameter WjFM. The figure is essentially the same as Figure 8.3 and, if plotted using D.R./ FM, the same as Figure 8.4. Such a plot is necessary to identify the domain of LCVD, namely, the energy-deficient domain or monomer-deficient domain. Based on this figure, 2.6GJ/kg (energy-deficient domain) and 21.8GJ/kg (monomer-deficient domain) were selected for analysis of coating characteristics.

The value of W/FM necessary to bring the plasma polymerization system into the monomer-deficient region is proportional to the value of the total bond... 

The relationship given by Eq. (4) is valid only in the monomer-deficient domain. The further increase of the... 

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