Doping chemical

Organic polymers are typically insulators since the valence electrons in sp orbitals are tightly bound to the individual atoms in the backbone and to the o--based covalent bonds that exist between 

Graph 1. Comparison of conductivities between inorganic materials and various conjugated polymers (d = doped). 

---

Fig. 1. (a) Comparison of normalised electrical conductivity of individual MWCNTs (Langer 96 [17], Ebbesen [18]) and bundles of MWCNTs (Langer 94 [19], Song [20]). (b) Temperature dependence of resistivity of different forms (ropes and mats) of SWCNTs [21], and chemically doped conducting polymers, PAc (FeClj-doped polyacetylene [22]) and PAni (camphor sulfonic acid-doped polyaniline [2. ]) [24]. 

Preliminary measurements of electrical conductivity of the conjugated derivatives of PBTAB, PBTB and PTTB obtained by the above treatment with bromine vapor are poor semiconductors with a conductivity of the order 10 °S/cm which apparently is not due to doping. Subsequent electrochemical or chemical doping of these polymers lead to 4-6 orders of magnitude increase in conductivity. Ongoing studies of the electrical properties of these conjugated polymers with alternating aromatic/quinonoid units will be reported elsewhere. 

It is a convenient aspect of electrochemical doping of the polymer that the electrolyte can provide the counter ion, although a similar result can be achieved via chemical doping under certain circumstances, e.g., Using a radical ion containing species such as sodium naphthalide, Na+ npthT, i.e.,... 

NB. Where only a current density was given in the original Ref. this is quoted in place of the polymerisation potential. c Counter ions are as incorporated during the electrochemical polymerisation process or by subsequent electrochemical doping unless suffixed with (chem.) which indicates the use of chemical doping. d Conductivities f-film, p-pressed pellet. 

Although it was initially believed that polyacetylene was unstable in contact with water under all conditions, it has been successfully chemically doped in aqueous solutions with no apparent degradation of the material [82] and its electrochemistry has also been investigated [135-137] from which it is clear that no degradation occurs in concentrated aqueous electrolytes. Reaction with water can occur under some circumstances however giving rise to sp3 carbons and carbonyl-type structures [129, 138-141],... 

A. Lobnik, I. Oehme, I. Murkovic, and O. Wolfbeis, pH optical sensors based on sol-gels chemical doping versus covalent immobilization. Anal. Chim. Acta 367, 159-165 (1998). 

Chen G, Bandow S, Margine ER, Nisoli C, Kolmogorov AN, Crespi VH, Gupta R, Sumanasekera GU, Iijima S, Eklund PC (2003) Chemically doped double-walled carbon nanotubes cylindrical molecular capacitors. Phys Rev Lett 27 257403... 

We believe that the luminescence at 1.0 eV is due to a structural damage induced by ion implantation rather than to a chemical doping effect, since the spectrum does not depend on the chemical species of the ion. These centers may be similar to the vacancies induced by 3-MeV electron-beam irradiation, as reported by Troxell and Watkins (1979), who find donorlike and acceptorlike levels —0.1 eV from the band edges. 

Plots in Figure 6.3 show leaching and response of pH sensor layers chemically doped starting from 3-(trimethoxysilyl)propylisocyanate (ICPS) and (glycidyloxypropyl)trimethoxysilane (GOPS) derivatized with the pH indicator AF, or physically doped in SiC>2 (from tetra-methylorthosilicate, TMOS) and in 50% phenyl-modified silica. 

---