Radiation polymer surfaces

Other techniques utilize various types of radiation for the investigation of polymer surfaces (Fig. 2). X-ray photoelectron spectroscopy (XPS) has been known in surface analysis for approximately 23 years and is widely applied for the analysis of the chemical composition of polymer surfaces. It is more commonly referred to as electron spectroscopy for chemical analysis (ESCA) [22]. It is a very widespread technique for surface analysis since a wide range of information can be obtained. The surface is exposed to monochromatic X-rays from e.g. a rotating anode generator or a synchrotron source and the energy spectrum of electrons emitted... 

The modihcation of polymer surfaces by graft copolymerization of a monomer or monomers from active sites has been reported in numerous references [165-169]. The most common techniques are y- and EB radiations, which generate surface radicals. Monomers can be present in gas phase (sublimed solid), in solution or as neat liquid. 

Reactive species can be generated prior to monomer exposure (preirradiation grafting), during contact with monomer, or, after the polymer surface has been saturated with monomer and isolated (postirradiation grafting). The radiation-induced (y-ray and EB) graft copolymerization of AA and vinyl acetate monomer onto PE surface has been reported [170]. The grafted sheets show excellent bonding with an epoxy adhesive and enhanced adhesion with aluminum. 

FIGURE 31.9 Change in the peel strength and radiation dose of ethylene-propylene-diene monomer (EPDM)/EPDM joint [Eo/y Eo/yl EPDM/natural mbber (NR)/EPDM joint [Eo/y NR Eo/yl and EPDM/Al joint [Eo/y Al]. (From Sen Majumder, P. and Bhowmick, A.K., in Polymer Surface Modification Relevance to Adhesion, Vol. It, Mittal, K.L., Ed., VSP, Utrecht, The Netherlands, 2000,425. With permission.)... 

The irradiation of a polymer surface with the high intensity, pulsed, fer-UV radiation of the excimer laser causes spontaneous vaporization of the excited volume. This phenomenon was first described by Srinivasan (1) and called ablative photodecomposition. The attention of many researchers was drawn to the exceptional capabilities of photoablation (2). Etching is confined to the irradiated volume, which can be microscopic or even of submicron dimensions, on heat-sensitive substrates like polymers. In most experimental conditions, there is no macroscopic evidence of thermal damage, even when small volumes are excited with pulses of... 

SOLID-PHASE ORGANIC SYNTHESIS ON RADIATION-GRAFTED POLYMER SURFACES APPLICATION OF SYNPHASE CROWNS TO MULTIPLE PARALLEL SYNTHESES... 

Scheme 7 shows how trisaccharides were prepared on a radiation-grafted polymer surface.20 The photolabile 4-hydroxymethyl-3-nitrobenzamido handle21 and jV-iodosuccinimide-triethylsilyltriflate coupling chemistry were used. Product purities were similar to those obtained using Tentagel macrobeads. 

Expanding the variety and properties of linker groups increases the scope of practical applications of radiation-grafted polymer surfaces for the parallel synthesis of organic compounds. Linker molecules have a bearing on the types of reactions that can be performed and the ease of isolation of products after cleavage. 

Chemical groups capable of ionic binding of heparin may be introduced onto the polymer surface by radiation grafting of ionogenic monomers, e.g., 2- or 4-vinyl-pyridine, dimethylaminoethyl methacrylate, etc. 64,65). Heparinization proceeds as shown below ... 

Mimotopes has been involved in the development, use, and commercialization of radiation-grafted polymer surfaces for multiple parallel synthesis since the late 1980s.10-12 Although other workers have reported the use of radiation-graft polymers in solid-phase synthesis,13,14 as far as we are aware, the graft polymer devices manufactured and sold by Mimotopes (SynPhase Crowns, SynPhase Lanterns) are the only current commercial products of this type. These products are presented in Fig. 1. The SynPhase Lanterns are the current design for small molecule synthesis. The initial... 

XPS of Polymer Surfaces Analytical Applications Radiation Damage Surface Modified Electrodes Interfacial Chemistry and Adhesion Surface Chemistry and Catalysis Mineralogy and Geochemistry Microelectronics Processing... 

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