**10. Ion implantation technology**

It has been approximately 50 years since researchers first began exposing polymeric materi‐ als to ionizing radiation, and reporting the occurrence of cross-linking and other useful ef‐ fects. Innovation in this field has by no means ended; important new products made possible through radiation technology continue to enter the marketplace, and exciting new innovations in the application of radiation to macromolecular materials are under explora‐ tion at research institutions around the world [132]. Ionizing radiation may modify physical, chemical and biological properties of materials [133]. Some of the surface characteristics be‐ ing successfully manipulated by radiation grafting include: chemical resistance, wetability, biocompatibility, dyeability of fabrics, and antistatic properties [132].

Ion implantation is an innovative production technique with which the surface properties of inert materials can be changed easily. It shows distinct advantages because it is environmen‐ tally friendly. Ion implantation can be used to induce both surface modifications and bulk property enhancements of textile materials, resulting in improvements to textile products ranging from conventional fabrics to advanced composites. Ion implantation was first done by Rutherford in 1906, when he bombarded aluminum foil with helium ions. Ion implanta‐ tion has been applied to metals, ceramics, plastics, and polymers [134].

Even though ion implantation is relatively complex in terms of the equipment required, it is a relatively simple process. Ion implantation consists of basically two steps: form plasma of the desired material, and either extract the positive ions from the plasma and accelerate them toward the target, or find a means of making the surface to be implanted the negative electrode of a high voltage system [135]. There are three methods commonly used for ion implantation. They differ in the way in which they either form the plasma or make the sur‐ face to be implanted the negative electrode. These methods are mass-analyzed ion implanta‐ tion, direct ion implantation and plasma source ion implantation [134].

In *mass-analyzed ion implantation*, the plasma that is formed in the ion source is not pure; it contains materials that one does not wish to implant. Thus, these contaminants must be sep‐ arated from the plasma. To perform this separation, the plasma source is placed at a high voltage and the part to be implanted is placed at ground. This produces a situation where the target is at a negative potential with respect to the plasma source. A negative electrode then extracts the ions from the source. The ions are then accelerated by a high voltage source to the target. Between the ion source and the target there is a large magnet, with magnetic field perpendicular to the direction of ion motion. Ions passing through this magnetic field are bent by the magnetic field. The amount of bending depends on the ion material being implanted and the strength of the magnet [135].

*Direct ion implantation* eliminates the need for the current limiting magnet found in mass-an‐ alyzed ion implantation by using an ion source that produces a plasma and ion beam of just the desired material. In direct ion implantation, the plasma is formed in the ion source and the ions extracted at high energies in a wide beam, passing through a valve directly into the end station, where the ion implant parts within the target area. In such a case, the beam cur‐ rent density can be high (10-50 mA), costs are greatly reduced, and relatively high through‐ put processing is possible [135].

It is difficult in practice to treat uniformly three-dimensional objects such as sockets in artifi‐ cial hip joints, without using sophisticated manipulating devices. Recently, however, an in‐ novative hybrid technology, *plasma source ion implantation* has been developed, which can, to a large extent, address the problems with conventional ion implantation of components with complex shapes [136]. In plasma source ion implantation (sometimes referred to as plasma ion immersion), the plasma source floods the chamber of the end station with plasma. Ions are extracted from the plasma and directed to the surface of the part being ion implanted by biasing the part to very high negative voltages using a pulsed, negative high voltage power supply [135].

One of the most recent ion implantation techniques is *metal vapor vacuum arc (MEVVA)*, a type of direct ion implantation. In the mid-1980s, Brown et al. at Lawrence Berkeley Labora‐ tory developed a new type of metal ion source, namely the MEVVA ion source. The MEV‐ VA source makes use of the principle of vacuum arc discharge between the cathode and the anode to create dense plasma from which an intense beam of metal ions of the cathode ma‐ terial is extracted. This metal ion source operates in a pulse mode [134].

**Figure 13.** MEVVA ion implanter [134]

creasing the energy of the electrons in e-beam treatments no significant superficial modifica‐ tions were observed. In fact, they promoted the cleavage of high-energy bond, such as S-S

It has been approximately 50 years since researchers first began exposing polymeric materi‐ als to ionizing radiation, and reporting the occurrence of cross-linking and other useful ef‐ fects. Innovation in this field has by no means ended; important new products made possible through radiation technology continue to enter the marketplace, and exciting new innovations in the application of radiation to macromolecular materials are under explora‐ tion at research institutions around the world [132]. Ionizing radiation may modify physical, chemical and biological properties of materials [133]. Some of the surface characteristics be‐ ing successfully manipulated by radiation grafting include: chemical resistance, wetability,

Ion implantation is an innovative production technique with which the surface properties of inert materials can be changed easily. It shows distinct advantages because it is environmen‐ tally friendly. Ion implantation can be used to induce both surface modifications and bulk property enhancements of textile materials, resulting in improvements to textile products ranging from conventional fabrics to advanced composites. Ion implantation was first done by Rutherford in 1906, when he bombarded aluminum foil with helium ions. Ion implanta‐

Even though ion implantation is relatively complex in terms of the equipment required, it is a relatively simple process. Ion implantation consists of basically two steps: form plasma of the desired material, and either extract the positive ions from the plasma and accelerate them toward the target, or find a means of making the surface to be implanted the negative electrode of a high voltage system [135]. There are three methods commonly used for ion implantation. They differ in the way in which they either form the plasma or make the sur‐ face to be implanted the negative electrode. These methods are mass-analyzed ion implanta‐

In *mass-analyzed ion implantation*, the plasma that is formed in the ion source is not pure; it contains materials that one does not wish to implant. Thus, these contaminants must be sep‐ arated from the plasma. To perform this separation, the plasma source is placed at a high voltage and the part to be implanted is placed at ground. This produces a situation where the target is at a negative potential with respect to the plasma source. A negative electrode then extracts the ions from the source. The ions are then accelerated by a high voltage source to the target. Between the ion source and the target there is a large magnet, with magnetic field perpendicular to the direction of ion motion. Ions passing through this magnetic field are bent by the magnetic field. The amount of bending depends on the ion material being

linkage, by enhancing depolymerization reaction [130].

biocompatibility, dyeability of fabrics, and antistatic properties [132].

tion has been applied to metals, ceramics, plastics, and polymers [134].

tion, direct ion implantation and plasma source ion implantation [134].

implanted and the strength of the magnet [135].

**10. Ion implantation technology**

132 Eco-Friendly Textile Dyeing and Finishing

Many techniques have been applied to produce the great potential of ion beam modification technology. It desired surface modifications, ranging from conventional flame treatments, ''wet'' chemical treatments, and electrical treatments (such as corona discharge), to modern plasma treatments and particle beam irradiation (electrons, ions, neutrons and photons) techniques. Among them, particle beam techniques are particularly attractive owing to their flexibility, effectiveness, and environmentally friendly nature compared with conventional techniques. Also, in the domain of particle beam techniques, the ion beam has proven more effective in modifying polymer surfaces than UV-light, c-ray, X-ray and electron beams. This is because energetic ions have a higher cross-section for ionization and larger linear energy transfer (LET, eV nm-1) than these conventional radiation types of comparable energy owing to their deeper range [136].

The phase diagram of carbon dioxide shown in Fig. 14 represents the interfaces between phases; at the triple point all three phases may coexist. Above the triple point, an increase in temperature drives liquid into the vapor phase, while an increase in pressure drives vapor back to liquid [120]. Above the critical point of carbon dioxide, it retains the free mobility of the gaseous state, but with the increasing pressure its density will increase towards that of a liquid. Solvating power is proportional to density, whilst viscosity remains comparable with

The Use of New Technologies in Dyeing of Proteinous Fibers

http://dx.doi.org/10.5772/53912

135

In the dyeing field, Schollmeyer and co-workers, among others, have demonstrated that both synthetic and natural fibres can be dyed with disperse and reactive disperse dyes in supercritical carbondioxide. However, the dyeing of natural fibres with water soluble dyes in supercritical carbondioxide has not yet been successful, since dyes such as reactive, acid and basic dyes have little solubility in this medium due to their high polarity [144]. One ap‐ proach to this problem was undertaken by Gebert et al. who examined wool and cotton fi‐ bers after attempting to open the fiber surface with a swelling auxiliary so that dye

In natural textiles, the dye molecules can be fixed by either physical (e.g. Van der Waals) or chemical (e.g. covalent) bonds. Since the dyes used in a ScCO2-dyeing process are non-polar and natural fibres are polar, the affinity between dyes and textiles is low so physical bonds are weak. Therefore, a dyeing process must be developed for dyeing natural textiles in ScCO2 with reactive dyes that create covalent dye-textile bonds. So far, several reactive dyes

known from conventional dyeing in water have been investigated in ScCO2:

**•** vinylsulphone dyes have been successfully used for silk and wool,

that of a normal gas, so the "fluid" has remarkable penetration properties [143].

**Figure 14.** Phase diagram of carbon dioxide [120]

molecules could be readily trapped in the fiber [145].

Numerous papers have appeared in recent years describing surface treatment using ions. Surface modification with ions typically involves fluencies of ~ 109 to 1014 ions/cm2 or in some cases, 1015 ions/cm2 ; higher fluencies may result in destruction of polymer, general‐ ly through carbonization. Many different ions have been employed for irradiating poly‐ mers, ranging from hydrogen and helium ions up to ions of heavy elements such as gold or uranium [132].
