Organic Macromolecules

Support materials were prepared by blending the fine power as stated in the later part of this case study. PVA was used as the binder. The organic macromolecule was used to create sufficient pores in the material when bumed out after a solid strong support was formed. Drying was performed in a high-temperature furnace. The shape and thickness of the support were based on the mass of the material and the way it was moulded. 

Another factor that can influence the environmental distribution of a chemical is the presence of charged groups. Some pollutants, such as the sodium or potassium salts of phenoxyalkanoic herbicides, dinitrophenols, and tetra- or penta-chlo-rophenol, exist as anions in solution. Others, such as the bipyridyl herbicides diquat and paraquat, are present as cations. In either case, the ions may become bound to organic macromolecules or minerals of soils or sediments that bear the opposite... 

From a historical point of view, organic macromolecules were developed first [5], and the reasons for this are basically twofold. On one side the ease of the preparation of these materials in a controlled and reproducible way [1] and the outstanding properties of the resulting organic polymers [6-8] on the other side the availability of oil on the market and the big effort put by oil companies into the production of a large variety of different monomers at very low prices [9]. 

The first phenomenon observed is the improved resistance of these materials to combustion, in a way that they may be classified as intrinsically self-extinguishing substrates. For instance, the LOI value for PTFEP is reported to be 48 [452], which is much higher than reported for classical organic plastics [283], while phosphazene fluoroelastomers have been considered as fire-retardant materials since the very beginning of their preparation and utilization [562]. Similarly to aryloxy- and arylamino- substituted POPs [389,390] (vide infra),it may be expected that the flame-resistance properties of phosphazene fluoroelastomers could be successively exported to stabihze organic macromolecules when blended with these materials. 

Magee, B.R., Lion, LW., Lemley, A. (1991) Transport of dissolved organic macromolecules and their effect on the transport of phenanthrene in porous media. Environ, Sci. Technol. 25, 323-331. 

There are three situations that appear to be relevant here. First, we may think of a solid polymer formed from the melt second, the much more compliant elastomers that initially come to mind when we think of rubber elasticity and third, polymer gels formed in polymer solutions. In each case the details of the physical chemistry of the macromolecules is crucial to the understanding of the structure that is formed. In this section we will concentrate on organic macromolecules because the rheology of these molecular systems is often the reason for their use. 

Polymers have some specific properties due to their organic nature. Thermoplastics, as seen in Chapter 1, are independent organic macromolecules with some sensitivity to environmental parameters temperature, moisture, deleterious solids, liquids, gases and other chemical products. They are also sensitive to mechanical loading, especially cyclic loads. Their specific properties, such as electrical or optical properties, are also important for their applications. 

Figure 3. Robust super high-spin organic macromolecule with a dendritic architecture based on a three-coordinated Cayley tree.

To conclude this section on polymols, we should note that we have used the term polymer almost exclusively to refer to organic macromolecules. The term plastic refers not only to organic substances of high molecular weight, but also to such substances that at some point in their manufacture have been shaped by flow. Thus, the term plastic is more specific than the term polymer, and this term carries with it an indication of its processing history. As we will see in Chapter 7, there are many materials that can be considered polymers, yet are formed by routes other than melt processing. 

Viscosity of Polymer Solutions. Polymer solutions are very common. Glues, pastes, and paints are just a few examples of commercially available aqueous suspensions of organic macromolecules. Also, recall from Chapter 3 that certain types of polymerization reactions are carried out in solution to assist in heat removal. The resulting polymers are also in solution, and their behavior must be fully understand in order to properly transport them and effect solvent removal, if necessary. 

Other soluble organic macromolecules from the biocrystalline layer of the egg shell have been demonstrated to bind Ca2+. At least six different Ca-binding macromolecules have been isolated and most of them have been purified to homogeneity407). 

Jirgensons, B., Natural Organic Macromolecules, Pergamon, New York,... 

Some insoluble organic macromolecules catalyze polar organic reactions (7). Asymmetric cyanohydrin formation is catalyzed by ami-nated cellulose with 22% optical yield and is an early example of this type of catalysis (8). Polypeptides that create a unique microenvironment through hydrogen bonding catalyze many organic reactions. Poly-[(S)-amino acids] accelerate the epoxidation of chalcone with alkaline... 

Entropic factors are a major problem for relatively large molecules. For organic macromolecules, the simulation of the probability W(S=k-In (W)) by molecular dynamics calculations or Monte Carlo simulations, has been used to calculate the entropy from fluctuations of the internal coordinates189"921. For simple coordination compounds the corrections based on calculated entropy differences are often negligible in comparison with the accuracy of the calculated enthalpies116,63,881. Therefore, the relatively easily available statistical term (Sstat) is usually the only one that is included in the computation of conformational equilibria (see Chapters 7 and 8). 

Polyphosphazenes comprise by far the largest class of inorganic macromolecules. At least 700 different polymers of this type have been synthesized, with a range of physical and chemical properties that rivals that known hitherto only for synthetic organic macromolecules.1... 

K.M. Khaylov, Dissolved organic macromolecules in sea water, Geokhimiya 5 (1968) 595-603. 

Watkins and Pfromm (1999) suggested a further method based on capacitance spectroscopy in the range 102 105 Hz to identify and tracking membrane fouling with organic macromolecules, such as sulfonated lignin, in real times. 

Black M.C. and McCarthy J.F. 1988. Dissolved organic macromolecules reduce the uptake of hydro-phobic organic contaminants by the gills of the rainbow trout (Salmo gairdneri). Environ. Toxicol. Chem. 7, 593-600. 

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