Synthetic polymer systematic study

JL HE WORLD IS BUILT FROM SILICON-BASED polymers. Silicate materials in many shapes or forms account for more than 90% of the land mass. Technologies associated with these materials have been developed through recorded history, but the science underlying these materials is, relatively, still in its infancy. The first systematic study of silicon chemistry was carried out in the first two decades of this century. The first useful synthetic or-ganosilicon polymers, the polysiloxanes, were developed in the late 1930s, and a new industry based on these synthetic polymers was bom in the early 1940s. This industry has grown rapidly worldwide to the point that it is now a multi-billion-dollar endeavor. 

The most widely evaluated, and the first systematically studied, of the types of synthetic polymers for biodegradability were the polyesters. The ASTM test described above was applied to several different polyesters as early as 1972 [23], In 1975 that type of evaluation was repeated and expanded to include soil burial on a much larger series of polymers. The ASTM test in both of these studies was based on a standard set of four fungi, and some of the results obtained from the later study are shown in Table 1 [25],... 

In recent years systematic studies using a wide variety of synthetic polymers have led to a considerable elucidation of the detailed mechanism of stabilisation of this kind, which has been given the name steric stabilisation. 

The first fully synthetic polymer to be introduced (1909) was a phenol-formaldehyde resin known as bakelite. Although the reaction had been discovered some twenty years previously, it was only after a careful and systematic study of it that it was properly controlled to give a useful thermosetting resin. In the late 1920s two other types of thermosetting resins followed, namely urea-formaldehyde, and alkyd resins. 

This systematic study, carried out throughout the 1980s, constituted a very thorough approach to both the synthetic aspects, with their corollary structural characterization, and a whole set of physical and technological properties. Elastomers as well as rigid polymers were prepared and their possible applications carefully examined on the basis of the specific performances determined for each one. Further additions to the basic investigation included the use... 

Systematic studies on amide functional bonded phases have been made by Engelhardt and Mathes . The functional trietho-xysilanes synthesized (see Table 2) were reacted with activated silicas of various pore sizes under anhydrous conditions and reflux. Toluene and xylene were found to be the most suitable solvents for achieving a high ligand density, while N-acetyl-amlnopropyl silica was shown to be the most suitable of the bonded phases for aqueous SEC of polar synthetic polymers and blopoIymers . 

The next decade, until the beginning of World War II, was devoted to systematic studies of such synthetic polymers as polystyrene, polyisobutylene, polyvinyl and polyacrylic derivatives, a series of copolymers and of polyelectrolytes. At the same time the work on polyo methylenes and on polyethylene oxide was continued and expanded. It was an amazing broad front along which Staudinger, together with an ever increasing number of able and devoted associates, invaded and conquered the newly created field of macromolecular science. 

The advent of living polymer technique revolutionalized the academic and industrial approach to block-polymers. It allowed systematic studies of properties of these materials as functions of structural factors since the difficulties arising from the unknown composition, the presence of homo-polymers in the block-polymers, etc., were avoided in this synthetic method. A few examples will illustrate the unexpected achievements. 

Contrary to what many people think, PLSNs are not a recent discovery. One of the earliest systematic studies of the interaction between a clay mineral and a macromolecule dates backs to 1949, when Bower described the absorption of DNA by montmorillonite. Even in the absence of X-ray diffraction (XRD) evidence, this finding implied insertion of the macromolecule in the lamellar structure of the silicate. In the case of synthetic polymers, Uskov found in 1960 that the softening point of polymethylmethacrylate derived by polymerisation of methylmethacrylate was raised by montmorillonite modified with octadecyl-ammonium, while in the following year Blumstein obtained a polymer inserted in the structure of a montmorillonite by polymerising a previously inserted vinyl monomer. In 1965 Blumstein first reported the improved thermal stability of a PMMA/clay nanocomposite. He showed that PMMA inserted between the lamellae of montmorillonite clay resisted thermal degradation under conditions that would otherwise completely degrade pure PMMA." ... 

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