Poly radiation resistant polymers

A substantial intramolecular protective effect by phenyl groups in polymers is shown by the low G values for Hz and crosslinking in polystyrene (substituent phenyl) and in polyarylene sulfones (backbone phenyl), as well as many other aromatic polymers. The relative radiation resistance of different aromatic groups in polymers has not been extensively studied, but appears to be similar, except that biphenyl provides increased protection. Studies on various poly(amino acid)s indicate that the phenol group is particularly radiation resistant. 

An early commercial interest in poly (olefin sulfones) was sparked by the low raw materials cost, but this interest waned when it became apparent that thermal instability is a general characteristic of this class of materials. In 1970 Brown and O Donnell reported that poly (butene-1-sulfone) is degraded by gamma radiation with a G(s) approaching 10, making it one of the most radiation-sensitive polymers known (38-39). The potential for use of this radiation sensitivity in the design of electron beam resists was quickly realized by several members of the electronics industry. Bell Laboratories, RCA, and IBM published studies demonstrating the potential of poly (alkene... 

The use of PMMA as a resist is favored by researchers because of its high resolution and contrast [Jubinsky et al., 1986]. However, its sensitivity is too low for commercial use. Jubinsky et al. [1986] describe an approach to improve its sensitivity, by blending it with a radiation-sensitive polymer, CO (poly(epichlorhydrin). Hydrin ) (Table 11.9). Three blends were made by dissolving CO and PMMA in tetrahydrofuran (CO/PMMA 20/80, 33/67 and 50/50), in the... 

Figure 11.20 shows the dose-dependent absorbance profiles of the carboxylic OH stretch (3100-3500 cm ) and the ester C-O-C stretch (around 1150 cm of a poly(CBN-co-NBCA) exposed to 248-nm radiation and baked afterward at 120, 130, 140, and 150°C. The carboxylic acid OH stretch and the carboxylic acid carbonyl (C O) stretch (1695-1705 cm ) both increase, while the ester carbonyl (C O) stretch (1730-1735 cm ) decreases with increasing dose of exposure (0-50 mJ/cm ), which allows us to follow the deprotection of the t-butyl ester group and the consequent conversion to a carboxylic acid group. The C-O-C (1150 cm ) stretch of the ester also decreases with dose of exposure, indicating the loss of the isobutylene group from the resist polymer. ... 

Lee et al. have irradiated different immiscible blends of poly(phenylene oxide) and poly(2-vinylnaphtalene). The objective of this work was to check if the latter polymer could improve the radiation resistance of the former. On the basis of thermal stability, mechanical properties and light resistance, no protective effect of poly(2-vinylnaphtalene) could be confirmed. 

The radiation resistance for a series of polyimides(PI), poly(aryl ether ether ketone) (PEEK), poly(aryl ether sul-phone) (PES), bisphenol A type Udel poly(aryl sulphone) (U-PS), and a poly(aryl ester) (U-Polymer) is shown to be excellent when compared to the related aliphatic polymers. G values for the evolution of gases were lower by factors of between 0.01 and 0.001 of the G values for the corresponding aliphatic polymers. From the study of gas evolution, the order of radiation resistance to 7-irradiati(Mi is [186] ... 

The various materials (often polymers) have to be chosen such that they are sufficiently radiation resistant to withstand the sterilization dose. Under the dose conditions, needed for sterilization some polymers such as polyethylene, polystyrene, poly(ethylene terephthalate), polyurethanes, and epoxides maybe stable, whereas others such as polypropylene, poly(methyl methacrylate), polyvinyl chloride (PVC) may not. When the radiation stability of the plastic... 

Less radiation resistant flexible chain polymers that have been studied by HREM include iPS [96], PTFE [97, 98], PE [99, 100], poly(/ -hydro-xybutyrate) [101], poly(p-phenylene sulphide)... 

Poly(chlorotrifluoroethylene) (PCTFE, Kel-F fluoropolymer) is a thermoplastic semicrystalline polymer with (-CF2CCIF-) repeating units [49], Typically, PCTFE is synthesized via a free radical polymerization using bulk, suspension, or emulsion techniques [50]. Compared with PTFE (Teflon fluoropolymer), which has similar chemical properties, there is asymmetry in the CTFE monomer unit due to the presence of the chlorine atom in CFCl groups. Consequently, the NMR features of PCTFE are more complicated due to the possible monomer- and stereo-sequence variations. Since PCTFE has various distinguished properties, including thermal, chemical, and radiation resistance, low vapor permeability, and electrical insulation [51,52], it has... 

Commercial polymer films can be easily microstructured using Laser Interference Patterning. In that way, the scope of the technique is increased since materials having well-known bulk and surface properties can be microstructured, allowing direct application, for example, in biomedical devices poly(etheretherketone) resists sterilization by radiation or heat treatment and it has been used to produce kidney dialysis machine components poly(etherimide) is used in harmonic scalpels polycarbonate (PC) is used in electrophysiology cathethers and poly(imide) (PI) is used in off pump coronary artery bypass devices.Moreover, the surface of already fabricated systems could be modified using this technique since it can be applied in air without altering the shape of the samples. 

This method uses a hydrophobic polymer with sufficient water and solvent resistance as the main chain to which hydrophilic monomers are chemically grafted by a catalyst, light or radiation. The polymer will be insoluble in water yet its electrical resistance is moisture dependent. This graft copolymer will be used for the sensor. As for the hydrophobic polymer, poly(tetrafluoroethylene)(PTFE) film or a porous poly(ethylene)(PE) film... 

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