Polymer film deposition

POEA), a conducting polymer. The measurements were carried out using both solution and polymer films deposited by the self-assembly technique (Paterno and Mattoso, 2001). Figure 16.21 presents the Raman spectra of FA, POEA, and POEA/ FA complexes in different concentrations of FA. 

A variation of the experimental methods described above is the xerographic discharge technique which is gaining wide acceptance in the study of polymeric systems. The polymer film deposited on a metallic substrate is corona charged and... 

Nucleation and growth kinetics — Nucleation-and-growth is the principal mechanism of phase transformation in electrochemical systems, widely seen in gas evolution, metal deposition, anodic film formation reactions, and polymer film deposition, etc. It is also seen in solid-state phase transformations (e.g., battery materials). It is characterized by the complex coupling of two processes (nucleation and phase growth of the new phase, typically a crystal), and may also involve a third process (diffusion) at high rates of reaction. In the absence of diffusion, the observed electric current due to the nucleation and growth of a large number of independent crystals is [i]... 

As the presented data are of rather poor quality, we would not like presently to discuss at length the problem we would prefer waiting for other sets of high resolution spectra that are scheduled for the near future (161... However in the meantime, we studied the origin of the HREELS broadening (Fig.7), to discover that other authors (2b.8.111 already stressed upon an influence of the substrate spectra of polymer films deposited onto a metallic substrate are of better quality than when deposited onto silicon or germanium. 

Figure 33.2 shows XPS spectra of the surfaces of the TMS plasma polymer film deposited on (Ar + H2) plasma-pretreated steel (a, b, c) and on O2 plasma-pretreated steel (d, e, f). As shown in the spectra, the surface of the plasma film is functional in nature with functional groups of C-OH, C=0, and Si-OH. Two films basically ended up with the same surface structure. This is also confirmed by XPS analysis of the film during the film aging in air after the film deposition, which indicated that the film surfaces were saturated with a fixed surface structure after a few hours of air exposure [4]. This is due to a well-known phenomenon that the residual free radicals of the plasma polymer surface reacted with oxygen after exposure to air [5]. Curve deconvolution of C Is peaks showed structures of C-Si, C-C, C-0, and C=0. The analysis clearly shows a silicon carbide type of structure, which is consistent with the IR results. The functional surfaces of TMS films provide bonding sites for the subsequent electrodeposition of primer (E-coat). 

Figure 33.2 XPS spectra of surfaces of TMS plasma polymer films deposited on (Ar + H2) plasma pretreated steel (a, b, c) and O2 plasma pretreated steel (d, e, f) adapted from reference [4].

Table XIV. Surface Tensions of Plasma Polymer Films Deposited...

Polymers which are available as powders of suitable aze and density, msy be packed directly in a column without a support for studies in the region of Tg. Hence it is not necessary to dissolve the sample prior to study. While most investigations involve thin polymer films deposited onto some inert support or the walls of a capillary tubing 19), studies have also been made with polymer powders 11, 20-22) or fibers 21). As a result the thermal history of the polymer sample can also be studied. 

Our screening concept is depicted in Fig. 19.2. For simplicity, operation of only one of the sensors from the sensor array is illustrated. An initially clean sensor crystal is exposed to a solvent containing a small amount of polymer followed by sensor withdrawal from the solution (Fig. 19.2a). Quantification of the residual dissolved polymer deposited onto the sensor is done by the measurements of the mass increase of the crystal, which is proportional to the amount of polymer film deposited onto the sensor from a polymer solution. Depending on the solvent-resistance of the polymers, the dissolution rate of polymers in solvents will be different as determined from multiple measurements of deposited polymers during the experiment (Fig. 19.2b). The measurements of frequency changes are done when the sensors are periodically withdrawn from the solvents and the solvents are evaporated. In this way, the measured signal change is indicative of the amount of the deposited material from the solution. 

Eor instance, if one would like to design a suitable redox polymer for a certain enzymatic reaction, it helps to think about the following factors. Eirst, the redox polymer needs to create a three-dimensional network that allows secure immobilization of the enzyme with a reasonable pore size. In addition, fast diffusion of the analyte, products, or counter-ions and fast ET kinehcs need to be ensured. The polymer film deposited as sensing layer creates a diffusion barrier which often prolongs the response time, shifts the linear measuring range, and decreases the sensitivity of the sensor. Second, the redox polymer should create a local... 

In addition, the use of electrodless glow discharge will produce different results than those with internal electrodes. In the former case, rare gases such as He, Ar was introduced from one end of the tubular reactor and the plasma was sustained by a rf coil outside the reactor. Gaseous monomer was fed into the afterglow of a rare gas and polymer film deposited on the substrate placed downstream. Yasuda, et. al. (18) observed that the deposition rate in electrodeless discharge was independent of the power input and increased in proportional to the square of the monomer pressure. 

The effect of reactor type on the quality of polymer film deposited is important to know. Use of the plasma probe could detect differences, although these were not investigated systematically. Tg decreased about 2x10 K in an internal electrode type reactor (compared to the electrodeless one). The geometry and size was close to that used by Kobayashi et al. ( ). In the former case, it was found that Tg remained essentially unchanged when the probes were placed at the center of the two disk electrodes and scanned across the diameter. 

Figure 6. Plots of In (A/Ao) as a function of pyrolysis time at 600°C for (a) SiH, SiCHs and (b) NH groups open symbols polymer film deposited without ammonia full symbols polymer film...

Figure 1. Representative agar dish growth tests of A. pullulans and Alternaria on polymer films deposited on ceramic tiles. Key top, unprotected film—mildew growth over entire dish middle, film protected by fungicide-polymer film—zone of inhibition around tile and bottom, film protected by polymer-boundfungicide—film is protected without wasteful zone of inhibition.

Development of the general plasma polymerization model is restricted by an essentially non-linear contribution of different plasma components in the process. Plasma particles are able to simultaneously build and destroy thin polymer films. Nevertheless, some models are able to describe a wide variety of experiments. The plasma polymerization model developed by Osipov and Folmanis (1973) is one of those. According to this model, charged particles activate adsorbed molecules, allowing then to cross-link with the polymer film. The rate of polymer film deposition from a non-equihbrium low-pressure discharge (number of deposited molecules per unit time) can be calculated in this case as... 

Figure 9-19. Schematic of an RF plasma system for plasma polymerization (polymer film deposition) (1) RF generator, (2) plasma zone (3) heated window (4) engine (5) rotating substrates (6) flexible connection (7) air valve (8) vacuum valve (9) manometer, (10) cooled trap (11) vacuum pump (12) quartz gauge for measurements of the film thickness (13) photodiode (14) registration system (15) polymer deposition chamber (16) laser (17) argon tank (18) valve (19) dose valve (20) tank with a manometer, (21) manometer.

Resistance of plasma-polymerized films with respect to electric breakdown can be quite high. This resistance increases at relatively low specific powers of the non-thermal discharges applied for polymer film deposition. As an example, plasma-polymerized fluorocy-clobntane film is characterized by breakdown electric fields 5 10 V/cmforafihnthickness of 150 nm, 6 10 V/cm for a film thickness of 100 nm, and 7-8 10 V/cmforafihnthickness of 75 nm. To compare, breakdown of a conventional PTFE film with thickness 0.1-... 

Mechanism and Kinetics of Piasma Poiymerization. Using kinetic relation (9-66), find the plasma polymerization regimes (derive criteria for the regimes) when the polymer film deposition rate depends on and is proportional to (1) only the flux of charged particles, (2) only the flux of relevant neutral species, and (3) fluxes of both active neutral and charged particles. 

Other devices such as the Cyrano Sciences, (Smiths Detection, Edgewood, MD), a handheld device using conductive polymer films deposited in an array on a ceramic substrate and the Micromachined Aconstic Chemical Sensor (Sandia National Laboratories, SNL), which is able to detect VOCs, explosives, illicit drngs, and chemical warfare agents, are also commercially available [32],... 

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