Hch H

is one of the simplest organic compounds, and it is a gas at room temperature. Figure 11.1 shows structural formulas of some examples of other hydrocarbons. The linear pentane molecule C5H12 has all single bonds, and the n-conjugated compound butadiene QH^ has alternating single and double bonds. The simplest aromatic compound, or ^-conjugated ring compound, that is, one with alternating single and double bonds, is benzene C6H6, and the figure shows two ways to represent it. It can also be expressed in the form Hcj>, where the phenyl group 0 is a benzene ring that is missing a hydrogen atom, corresponding to —C6H5, where the dash (—) denotes an incomplete chemical bond. Naphthalene (CI0H8) is the simplest condensed ring (fused ring) aromatic compound. The bottom panel of Fig. 11.1 shows the triple-bonded compounds acetylene and diacetylene. Aromatic compounds can contain other atoms besides carbon and hydrogen, such as chlorine (CI), nitrogen (N), oxygen (O), and sulphur (S), as well as atomic groups or radicals such as amino (—NH2) nitro (—N02), and the acid group —COOH.

H H H H H HC-C-C-C-CH H H H H H Linear hydrocarbon (pentane) H H H H C=C-C=C H H 7i - conjugated butadiene

Naphthalene Aromatic Compounds

HOCH HCsC-C®CH Acetylene Diacetylene

Figure 11.1. Examples of organic molecules. Acetylene and diacetylene serve as monomers for the formation of polymers.

The present chapter emphasizes experimental aspects of polymeric nanoparticles. Insights can also be obtained about these nanoparticles by computer simulation and modeling, and the article by Sumpter et al. (2000) can be consulted for some details on this approach.

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