Irradiation of polymer films

In our study we have found that UV-light greatly accelerates the rate of ozone attack at the polypropylene surface. Presented results were undertaken to determine mechanism of the photo-oxidation of polypropylene surface upon UV-irradiation of polymer films in ozone. 

Figure 1. Device for controlled irradiation of polymer films—rotating plate with specimens (a), source (b)9 ventilator (c), and electronics for controlling of light intensity, specimens temperature, and rate of rotations, (d)...

Polymers were deposited onto the quartz crystal (0.8 cm diameter) by casting from chloroform solution. The area coated with the polymer film was usually 0.13 cm2. The quartz crystal was placed in the middle of the sealed glass vessel which had a quartz window for UV irradiation. 2M KNO 3 aqueous solution was placed at the bottom of the vessel to control its humidity (RH=95%) at 25 "C. Irradiation of polymer films on the quartz crystal through the quartz window of the vessel was carried out with 254-nm light using a 5-W low-pressure Hg lamp (Toshiba LP-llB). The intensity of the incident light determined with a chemical actinometer (potassium ferrioxalate) (10) was 0.1 mJ/cm2 - sec at 254 nm. 

Venkatesan, X, Wolf, X, Allara, D., Wilkens, B. J., and Taylor, G. N., Synthesis of novel inorganic films by ion beam irradiation of polymer films, Appl. Phys. Lett., 43, 934-936 (1983). 

Irradiation of polymer films (and powders, etc.) using X-rays, y-rays, or electron beams (as at Surrey, see previous section) is a flexible way to introduce various functional groups on the polymer backbones (Scheme 2.2). A wide range of... 

This approach allows one to create by gamma-irradiation of polymer films with a profile of refractive index distribution, which is a necessary condition for the creation of a profile which achieves correction of residual aberration in optical system, and the eieation of the integral optics elements, light-guides and transformers of light beams [76]. 

ATR-FTIR technique presents a crucial role in the assessment of stmctural modifications during UV irradiation of polymer films. Authors introduced a difference spectrum C (Fig. 3—reproduced with kind permission from Elsevier— License No. 3723021063514) between initial sample spectrum and that of sample after irradiation [47]. 

Several approaches have been undertaken to construct redox active polymermodified electrodes containing such rhodium complexes as mediators. Beley [70] and Cosnier [71] used the electropolymerization of pyrrole-linked rhodium complexes for their fixation at the electrode surface. An effective system for the formation of 1,4-NADH from NAD+ applied a poly-Rh(terpy-py)2 + (terpy = terpyridine py = pyrrole) modified reticulated vitreous carbon electrode [70]. In the presence of liver alcohol dehydrogenase as production enzyme, cyclohexanone was transformed to cyclohexanol with a turnover number of 113 in 31 h. However, the current efficiency was rather small. The films which are obtained by electropolymerization of the pyrrole-linked rhodium complexes do not swell. Therefore, the reaction between the substrate, for example NAD+, and the reduced redox catalyst mostly takes place at the film/solution interface. To obtain a water-swellable film, which allows the easy penetration of the substrate into the film and thus renders the reaction layer larger, we used a different approach. Water-soluble copolymers of substituted vinylbipyridine rhodium complexes with N-vinylpyrrolidone, like 11 and 12, were synthesized chemically and then fixed to the surface of a graphite electrode by /-irradiation. The polymer films obtained swell very well in aqueous... 

The irradiation of polymers is widespread in many industries. For example, microlithography is an essential process in the fabrication of integrated circuits that involves the modification of the solubility or volatility of thin polymer resist films by radiation. The sterilization by radiation of medical and pharmaceutical items, many of which are manufactured from polymeric materials, is increasing. This trend arises from both the convenience of the process and the concern about the toxicity of chemical sterilants. Information about the radiolysis products of natural and synthetic polymers used in the medical industry is required for the evaluation of the safety of the process. 

The relationship between the thickness of polymer films containing about 10 mol-% of pendant photosensitizer groups and the conversions of the —C bonds after 10 min. irradiation is shown in Figure 5. The photochemical reactivity of PCEVE-NNVE decreased slightly with increasing thickness of the film. Interestingly, the reactivity of PCEVE-NPVE was not influenced by the thickness of the film in contrast to the self-sensitized polymers previously... 

Chien and Cada [42] have prepared optically active and photoactive SCLC copolymers, 15, with the 4-alkoxyphenyl-4 -alkoxycinnamate chromophore, with the intention of creating LC polysiloxane networks that could be used to prepare macroscopically oriented organic ferroelectric polymers for electro-optical devices. Optical activity was introduced into the polymer by the use of a chiral spacer. Those copolymers which were mesogenic exhibited properties characteristic of a Sc. phase. UV-irradiation of thin films of the polymers in their mesomorphic states at 90°C, led to a loss of the IR absorption at 1635 cm-1 that is due to the cinnamate double bond, and to cross-linking. Long-term irradiation led to... 

Havens and Bell performed an electron beam irradiation of methylene-bridged aromatic polyesters, which were synthesized by polycondensation between two pairs of aromatic diacid chlorides and 3,3 -methylenediphenol or 4,4 -methylenediphenol [54]. They found that irradiation of thin films of these polyesters at room temperature resulted in some chain extension and cross-linking, and that irradiation at a temperature near or above the glass transition temperatures of the polymers greatly enhanced the tendency for the polymers to crosslink. 

It is now well established that organic polymers are rather more sensitive to various ionizing radiations. In a recent study (23) it has been shown that the irradiation of polystyrene films by 20 MeV 28gi beam results in ion-induced modifications of the sample because a significant quantity of H and C nuclei is released when the beam dose is increased above 1012 ions cm 2. Similar effects of erosion of H and C profiles of plasma-polymerized hexamethydisilasene (HMDSN) thin... 

Rutherford Backscattering Spectroscopy (RBS) is an established technique for analysis of inorganic materials. Recently, several applications of RBS on polymer films have been reported however, the effect of ion beams on these surfaces has not been well documented. RBS has been used to determine fluorine distribution in polymers. Since ion beam irradiation of polymers can induce chemical changes, instrumental parameters need to be optimized to minimize damage. 

The use of radiation to modify the physical properties of polymers has become a very important industry with products such as electrical cables with insulation capable of withstanding high temperatures and heat-shrinkable polyethylene. However, of direct relevance to this symposium was the recognition in the early 1970 s that electron beam irradiation of pol3mier films could provide an important lithographic tool for the manufacture of microelectronic components. For consideration of the general principles of these processes see, for example, references (66) and (67). The products required In this field are complex requiring both microscopic... 

A large number of papers has appeared on the subject of excimer laser exposure of polymer films (16-21). Most of these have dealt with the phenomenon of photoablation. A few have observed intensity dependent photochemistry (22,23). The latter authors were concerned with the effect of exposure intensity on resist development characteristics. The utility of nonlinear photochemistry for image modification has not been explored except in our earlier communication, in which strongly nonlinear irreversible bleaching was observed for KrF laser irradiation of acridine/PMMA films with lOnsec pulses (5). 

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