Aromatic polymers generation

Onium salts have been widely used as an acid generator for photo-, EB, and x-ray resist. In addition, aromatic polymers such as novolak and polyhydroxystyrene have been often used as a base polymer for EB and x-ray resist. The reaction mechanisms in a typical resist system have been investigated by pulse radiolysis [43,52,77-88], SR exposure [79,80,83-85], and product analysis [88]. Figure 6 shows the acid-generation mechanisms induced by ionizing radiation in triphenylsulfonium triflate solution in acetonitrile. The yields of products from electron beam and KrF excimer laser irradiation of 10 mM triphenylsulfonium triflate solution in acetonitrile are shown in Fig. 7 to clarify the... 

Thermal decomposition of the polymer generates fragments of the polymeric chain and dibenzofuran derivatives. At higher temperatures CO, CO2 and aromatic hydrocarbons are formed. In the presence of potassium carbonate and heating around 340° C, PEKEKK undergoes transesterification reactions forming polymers with ether-ketone ether-ketone-ketone sections. Some results reported in literature regarding thermal properties of these polymers are indicated in Table 9.3.11. 

The high technology thermoplastic aromatic polymers. In the mid-1980s ICI developed a new generation of thermoplastic aronratic polymers, in particnlar the amorphorrs polymer poly ether snlphone (PES) and the senri-crystalline polymer polyetheretherketone (PEEK) (Cogswell, 1989) they also developed the pre-impregnation of continnons fibres... 

Anodic one-electr(Mi oxidation of an aromatic monomer generates its radical cation. The radical coupling and the following deprotonation lead to form a neutral dimer. Further sequential oxidation of the dimer and subsequent radical coupling results in the formation of oligomer and polymer (Fig. 1). They usually deposit on the anode due to their low solubility in the electrolytic media. 

The faster polymer generation at rising proton concentrations in aqueous solutions can be explained from the initial protonation of pyrrole in the a position, as a previous step in the general mechanism of electropolymerization [142]. As is well known, pyrrole can be protonated in all the possible positions (a, (i and N) resulting in three kinds of cationic species (Figure 10.14) [21,136], although the more stable position for protonation is the a carbon. A general feature of protonated pyrrole molecules is that they are not aromatic and hence they are more easily oxidable. In this way we can propose an electrochemical mechan-... 

The excimer laser irradiation of synthetic fibers made of highly absorbing polymers, e.g. aromatic polymers such as PET and aramids as well as aliphatic polymers such as polyamide-6 and -6.6 (PA), generates a... 

High-performance fiber-reinforced composites are being used in diverse applications such as aerospace, nuclear plants, radiation equipment, and particle-physics generators. Because the polymers are exposed to high-energy radiation in most of these applications, the effect of radiation on the structure and physical properties of such aromatic polymers is of great interest. However, this aspect of PPS has not received considerable attention. 

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