Benzene Repeat Units

Homologous series with the same units, adding repeat units of — CH2—or benzene rings... 

Polyaniline is a repeating unit of benzene rings each joined by an N—H group (13, Fig. 13.7). This polymer and its derivatives are of interest because they are electrically conductive when doped with oxidants. This material is prepared by oxidation of aniline electrochemically, ° enzymaticaUy, or with simple chemical reagents. Polyaniline can be formally regarded as a polymer of... 

Thermoplastic Polymers. Most thermoplastic polymers are used in high-volume, widely recognized applications, so they are often referred to as commodity plastics. (We will elaborate upon the distinction between a polymer and a plastic in Chapter 7, but for now we simply note that a plastic is a polymer that contains other additives and is usually identified by a variety of commercial trade names. There are numerous databases, both in books [1] and on the Internet [2], that can be used to identify the primary polymer components of most plastics. With a few notable exceptions, we will refer to most polymers by their generic chemical name.) The most common commodity thermoplastics are polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC) and polystyrene (PS). These thermoplastics all have in common the general repeat unit -(CHX-CH2)-, where -X is -H for PE, -CH3 for PP, -Cl for PVC, and a benzene ring for PS. When we discuss polymerization reactions in Chapter 3, we will see that all of these thermoplastics can be produced by the same type of reaction. 

The optical nonlinearity is strongly dependent on the extent of ir-electron delocalization from one repeat unit to another in the polymer (or oligomer) structure. This effective delocalization is not always equally manifested but depends on the details of repeat unit electronic structure and order. For example, in a sequentially built structure, the ir-delocalization effect on Y is found to be more effective for the thiophene oligomers than it is for the benzene oligomers (5). 

The copolymerisation of CO2 and l,4-bis-(Al,IV-diethylamino-ethynyl)benzene affords a quantitative yield of a poly(pyran-4-one) (Mn 10000) without the need for a catalyst. Its repeat unit has been synthesised to assist in the structure elucidation of the polymer (95CC2417). 

The following aspects will be addressed. (1) Conjugated polymers with benzene-derived repeat units (section II) typical examples are the already mentioned poly-/>phenylene (PPP) 6,43 polyphenylene-vinylenes (PPV) 9,43 and polyphenyleneethinylenes (PPE) 25.44 Some typical questions are obvious how do the aromatic or olefinic units interact via the formal single bonds and how far does an extra charge or an excitation delocalize over the chain. (2) Large... 

From this viewpoint, the role of superbenzene as a repeat unit of giant fused PAHs is analogous to using benzene as a building block to produce fused homologues. This is clear in the naming of the supernaphthalene 63,160 superphenalene 93,160 and supertriphenylene 64,160 in which two, three, and four superbenzenes are fused, respectively. 

Aromatic polymer—A polymer with a predominance of benzene ring-containing repeat units. Polystyrene is an example. 

As an approach to a better understanding of adhesion mechanisms between polyimide and copper, we have studied the interaction between a set of model molecules for a polyimide and vapor deposited polycrystalline copper. Thin films and adsorbates of benzene, phthalimide, methyl-phthalimide, benzene-phthalimide, and malonamid, which are representative of separate parts of the polyimide repeat unit, were deposited in situ on clean copper and examined by means of X-ray and Ultraviolet photoelectron spectroscopy (XPS and UPS). In contrast to the previously observed bonding to the carbonyl oxygen in polyimide, as Cu is deposited on polyimide, our results show that most of these polyimide model molecules bond to Cu, through electron transfer, with the imide nitrogen atom as the primary reaction site. 

What makes macromolecules different from small molecules, such as benzene or ethylene, is their size. A typical polymer chain may consist of several thousand atoms. These atoms are connected together, however, in a way that does not differ from the type of bonding encountered in small molecules. If we consider polyethylene, its repeat unit consists of two methylene groups connected at the two carbons by single bonds ... 

Under the influence of light, benzene and alkylbenzenes copolymerize with blsmaleimldes by successive 2 -t- 2 and 2 + 4 cycloaddltlon reactIonsL2 l (Reaction 2). Although only the head-to-tall repeating unit Is shown In Reaction 2, It should be recognized that head-to-head and tall-to-tall units can... 

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