Molecular materials history

Sephton et al. (1998, 1999, 2000) used hydrous pyrolysis followed by supercritical extraction to examine insoluble organic matter in Orgueil (CIl), Murchison (CM2), and Cold Bokkeveld (CM2). The hydrous pyrolysates obtained for the three meteorites displayed a remarkable degree of qualitative similarity suggesting that the macro-molecular materials in different carbonaceous chondrites are apparently composed of essentially the same aromatic structural units, predominantly one to three ring alkyl-substituted aromatic structures. Significant quantitative differences were observed, however, and these were interpreted as indications of the different parent body histories of the three meteorites (Sephton et al., 2000). 

The properties of polymers and organic molecular materials are largely dependent on their molecular structures, architecture, and processing history. Electron miaoscopy (EM) is a powerful tool... 

The discovery and development of polypropylene, the one genuinely new large tonnage thermoplastics material developed since World War II, forms part of what is arguably the most important episode in the history of polymer science. For many years it had been recognised that natural polymers were far more regular in their structure than synthetic polymers. Whilst there had been some improvement in controlling molecular architecture, the man-made materials, relative to the natural materials, were structurally crude. 

An important subdivision within the thermoplastic group of materials is related to whether they have a crystalline (ordered) or an amorphous (random) structure. In practice, of course, it is not possible for a moulded plastic to have a completely crystalline structure due to the complex physical nature of the molecular chains (see Appendix A). Some plastics, such as polyethylene and nylon, can achieve a high degree of crystallinity but they are probably more accurately described as partially crystalline or semi-crystalline. Other plastics such as acrylic and polystyrene are always amorphous. The presence of crystallinity in those plastics capable of crystallising is very dependent on their thermal history and hence on the processing conditions used to produce the moulded article. In turn, the mechanical properties of the moulding are very sensitive to whether or not the plastic possesses crystallinity. 

Cyanide complexes have a venerable history (see CCC S )),1 and find utilization in many industrial processes including as synthetic catalysts e.g., Co cyanides on inorganic supports catalyze alkylene oxide polymerization,187 molecular magnetic materials, in electroplating, and in mining. Their pharmacology and toxicology is well explored... 

The history of commercially significant molecular sieve materials from 1954 to 2001 was reviewed in detail by one of us (E.M.F., ref [1]) Highhghts from that review and the subsequent history are presented here. The reader is referred to Chapter 2 for the structures of the materials and to Chapter 3 and ref [25] for a detailed discussion on zeolite synthesis. 

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