Chemical and Physical Interactions in Covalent Polymers Implanted with Transition Metals
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CHEMICAL AND PHYSICAL INTERACTIONS IN COVALENT POLYMERS IMPLANTED WITH TRANSITION METALS
PEHR E. PEHRSSON,* D. C. WEBER,** N. KOONS,** J.E. CAMPANA,** S.L. ROSE** *Catholic Univ. of America, Wash., D.C. **Naval Research Laboratory, Wash., D.C.
ABSTRACT Multiple analytical techniques including FABMS, XPS/Auger, magnetic susceptibility, and conductivity are used to probe the effects of transition-metal implantation on the structural and physical properties of covalent polymers and HOPG. Post-implantation chemistry and solid-state interactions between the implanted atoms and the polymer are investigated.
Introduction and Review Ion implantation is a technique not usually applied to organics, particularly polymers. However, its unique ability to introduce large nonequilibrium quantities of atomically dispersed species into a solid matrix has recently demonstrated potential for unique and useful chemistries; viz, implantation of halogens into certain polymers to greatly increase their conductivity[l]. Beam damage to the original polymeric matrices in the energy and fluence regimes used in our experiments is substantial and irreversible. High kinetic energy ions striking the surface of the polymer target are slowed by electronic stopping mechanisms, resulting in polymer chain scission, crosslinking, and bond disruption[2]. Different polymers exhibit varying resistance to such damage, primarily as a result of variations in chain substituents and the degree of unsaturation. As the implanted atoms slow, nuclear stopping displaces large numbers of atoms in the polymer chains[3], destroying their long-term periodicity, and ultimately obliterating the molecular structure of the original monomeric units. In addition, preferential sputtering and the diffusion of volatile reaction products alter the sample stoichiometry. Once in the matrix, the implanted species are subject to a variety of possible interactions. They may react chemically with the surrounding matrix analogous to the formation of carbides by implantation of carbon into certain bulk metals[4]. Alternatively, they may be physically or electrostatically trapped and isolated by the matrix, as seen+ in the vapor deposition of metal vapors on defect-saturated surfaces of Ar -sputtered graphite[5]. The metal atoms stick at the point of initial contact with the surface, and so are slow to nucleate and develop the bulk metal electronic structure. Or, the implanted atoms may diffuse either into the sample bulk or to the surface, with the accompanying prospect of nucleation and precipitation, similar to metal atoms vapor deposited on a graphite surface, which behave as a two-dimensional gas and diffuse on the surface until encountering a defect or nucleation site[5-6]. In this report, we describe the implantation of transition metal ions into a variety of covalent polymer matrices, followed by analysis and characterization of the resulting products.
Mat.
Res. Soc.
Symp. Proc. Vol.
27 (1984) (Elsevier
Science Publishing Co., Inc.
430
Experimental The polymers used w
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