Physical surface modification

Keywords Polydimethylsiloxane (PDMS), microfluidic devices, surface modification, physical adsorption, inner migration, high... 

Energetic particles interacting can also modify the structure and/or stimulate chemical processes on a surface. Absorbed particles excite electronic and/or vibrational (phonon) states in the near-surface region. Some surface scientists investigate the fiindamental details of particle-surface interactions, while others are concerned about monitormg the changes to the surface induced by such interactions. Because of the importance of these interactions, the physics involved in both surface analysis and surface modification are discussed in this section. 

Physically or chemically modifying the surface of PET fiber is another route to diversified products. Hydrophilicity, moisture absorption, moisture transport, soil release, color depth, tactile aesthetics, and comfort all can be affected by surface modification. Examples iaclude coatiag the surface with multiple hydroxyl groups (40), creatiag surface pores and cavities by adding a gas or gas-forming additive to the polymer melt (41), roughening the surface... 

Surface modification of a contact lens can be grouped into physical and chemical types of treatment. Physical treatments include plasma treatments with water vapor (siUcone lens) and oxygen (176) and plasma polymerization for which the material surface is exposed to the plasma in the presence of a reactive monomer (177). Surfaces are also altered with exposure to uv radiation (178) or bombardment with oxides of nitrogen (179). Ion implantation (qv) of RGP plastics (180) can greatiy increase the surface hardness and hence the scratch resistance without seriously affecting the transmission of light. 

The resultant tailored interface is often vastly superior for biomedical applications over the native silicone interface. Furthermore, surface modification maintains the low materials cost and favorable bulk properties of the original silicone elastomer. The modification methods can be divided into physical and chemical techniques. 

Capillary electrophoretic separations are performed in small diameter tubes, made of Teflon, polyethylene, and other materials. The most frequently used material is fused silica. Fused silica capillaries are relatively inexpensive and are available in different internal and external diameters. An important advantage of a fused silica capillary is that the inner surface can be modified easily by either chemical or physical means. The chemistry of the silica surface is well established due to the popularity of silica surfaces in gas chromatography (GC) and liquid chromatography (LC). In capillary electrophoresis, the silica surface is responsible for the EOF. Using surface modification techniques, the zeta potential and correspondingly the EOF can be varied or eliminated. Column fabrication has been done on microchips.13... 

Physical surface modifications Adsorption is probably the simplest way to change the EOF on purpose by using appropriate additives. EOF modification by adsorption can be used on both uncoated and coated capillaries. The surface of uncoated fused silica... 

Spherical porous silica gel is the easiest stationary phase material to handle however, although it is physically strong it is chemically unstable. Surface modification can expand its capability for different modes of chromatography, such as normal-phase, reversed-phase, size-exclusion, and ion-exchange liquid chromatography. These stable modifications are performed by chemical deriva-tization of the surface silanol groups. 

In order to overcome this drawback, there are two main approaches for the surface modification of carbon nanostructures that reoccur in the literature. The first one is covalent functionalization, mainly by chemical bonding of functional groups and the second one is noncovalent functionalization, mainly by physical interactions with other molecules or particles. Both strategies have been used to provide different physical and chemical properties to the carbon nanostructures. Those that will be presented here are only a few examples of the modifications that can be achieved in carbon nanostructure surfaces and composite fabrication. 

The surface modification of wood is defined as the application of a chemical, physical or biological agent to the wood surface in order to effect a desired performance improvement. 

During the last decade STM has proven to be a unique tool for the synthesis of novel structures. Perhaps the most elegant demonstration of this was the positioning of individual Xe atoms on Ni(l 10) with atomic precision in a low-temperature UHV experiment [516]. A variety of structures that exhibit the physics of quanmm confinement have been produced in this manner [517], and more recently, the manipulation of individual molecules at room temperature has been demonstrated [518,519]. It is now clear that there are several possible mechanisms for atomic and/or molecular manipulation [520]. Similarly, two reviews of various related schemes for sub-[im surface modification are also available [521,522]. In addition to published... 

For example a polymer s interfacial characteristics determine chemical and physical properties such as permeability, wettability, adhesion, friction, wear and biocompatibility. " However polymers frequently lack the optimum surface properties for these applications. Consequently surface modification techniques have become increasingly desirable in technological applications of polymers. - ... 

In addition to C onions, C atoms condense into various kinds of chemically bonded forms, and they are known to have excellent physical properties depending on the bonding nature. This means that research and applications not only in the materials science but also in other scientific fields are expected. At JAERI, the optimum growth conditions have been successfully obtained for the preparation of high-quality Cgo, diamondlike carbon, and nanocrystalline diamond by means of ion-beam-assisted deposition [80-82]. The susceptibility of Ni/Cgo thin films to thermal treatment, the formation of nanocrystalline diamond and nanotubes due to codeposition of Co and Ceo, and the surface modification of glassy... 

In most practical uses of polymeric particles, their surfaces play a very important role by taking part in interfacial interactions such as recognition, adsorption, catalytic reactions, etc. When we want to use polymer particles, we first check whether the chemical and physical structures of the surfaces meet the purpose. If some of them do not satisfy the criteria, we may seek other particles or try to modify the existing particles. This chapter mainly deals with the modification of surface of existing particles. In addition to chemical modification of particle surfaces, modification of the morphology of particles is also described. 

Ivanov LV, Chernykh VP, Kartel NT et al (2008) Study of mechanisms of carbon nanotubes cytotoxicity. In Chemistry, Physics and Technology of Surface Modification. Proceedings of ISC, Kiev 34-36... 

A wide variety of parameters can directly affect the chemical and physical characteristics of a plasma, which in turn affect the surface chemistry obtained by the plasma modification. Some of the more important parameters include electrode geometry, gas type, radio frequency (0-10 ° Hz), pressure, gas flow rate, power, substrate temperature, and treatment time. The materials and plasmas used for specific biomedical applications are beyond the scope of this text, but the applications include surface modification for cardiovascular, ophthalmological, orthopedic, pharmaceutical, tissue culturing, biosensor, bioseparation, and dental applications. 

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