Polyacetals characteristics

A characteristic feature of the mass spectra of the polyacetates is the presence of ion M+43 formed by interaction of ion CHjCO with the starting, neutral molecule. The mass spectra of acetates are also characterized by the presence of triacetoxonium (m/e 145) and diacetoxonium (m/e 103) ions ... 

Dictyopterene B (1) is one of the polyacetate-derived cyclopropane-containing natural products and is isolated from the essential oil of brown algae Dictyopteris plagiogramma and D. australis. This tri-olefinic cyclopropane is a sex pheromone released by the female plants to attract male gametes. This unusual Cn hydrocarbon along with other Dicyopteris constituents has a characteristic odor associated with ocean beaches. A second... 

Bowers, A.R. and Huang, C.P, Adsorption characteristics of polyacetic amino acids onto hydrous 7-AEO, J. Colloid Interf. Sci., 105, 197, 1985. 

The most stable polyacetal polymer is polyformaldehyde (or polyoxymeth-ylene, POM) this is the only polyacetal that has reached commercial production. This resin has unique properties (e.g., selflubrication) and is very widely used in automotive applications such as engineering plastics. Acetals are widely used engineering thermoplastics with high load-bearing characteristics and low coefficients of friction. Currently, over 200 million lb of acetals are molded and extruded in the United States. 

Ladybird beetles produce a wide variety of polyacetate or fatty acid-derived alkaloids, many of which closely resemble the ant venom alkaloids described in the previous section. The original discovery of coccinelline (75) and precoccinelline (100) (Figure 32) in blood of the European ladybird beetle, C. 1-punctata had been motivated in part by these beetles aposematic coloration and their tendency to reflex-bleed when molested. Many ladybird beetle species share these characteristics and correspondingly are chemically protected by alkaloids as well. The carbon skeletons of almost all of these alkaloids are based on simple unbranched chains. The structures, biology, and laboratory syntheses of ladybird beetle alkaloids have been reviewed previously by Daloze et al and by Glisan King and Meinwald. ... 

Some aspects of these inherent characteristics were addressed a few years later in the early 1980s when the preparation of polyacetals was described using a single (A-B) monomer 7 comprised of a vinyl ether and a hydroxyl moiety that could be polymerized to give a polyacetal [30] (Figure 13.2b). However, the vinyl ether moiety in monomers such as 7 must still be protected from hydrolysis, and as will be seen, the approach in Figure 13.2a is more flexible and has been followed to prepare different polyacetals for potential biomedical use [23,31,34]. 

A related strategy described by Frechet (Figure 13.5b) utilizes a bis-diene amide monomer 21 that possesses an internal acetal/ketal moiety [86]. Monomer 21 is a bis-acrylamide capable of conjugate or Michael addition at unsubstituted double bonds. A diamine such as piperazine 22 can be used to prepare acetal/ketal polyamidoamines 23. One characteristic of polyacetal polyamidoamines 23 is they will be cationic and have been used in stndies to complex oligonucleotide analogues (e.g., siRNA and DNA). 

Polyacetals are engineering plastics because of their high hardness, rigidity and tensile strength, good abrasion and wear resistance, and favorable low frictional properties, all of which are advantages over other materials. Since polyacetals absorb virtually no water, they have excellent weight retention characteristics. Polyacetals only dissolve in hexafluoroacetone hydrate at... 

Most commonly used matrix materials for thermoplastic PMC in construction are polyolefinics (PE, PP), vinylic polymers (PVC, PTFE), polyamides (Nylons), polyacetals, polyphenylenes [polyphenylene sulfide (PPS)], polysulfone and poly-ether-ether-ketone (PEEK). All of these are discussed in the first part of this chapter and some of their characteristic properties are presented in Table 6.8. 

Property data for GRTP s are presented in two major breakouts. In the first breakout, the basic resins—styrene acrylonitrile (SAN), polycarbonate, polysulfone, polyacetal, polypropylene, polyphenylene oxide (PPG), nylon, modified PPG, and polyvinyl chloride—are treated as the independent variables and the physical, mechanical, electrical, thermal, chemical, and weathering characteristics are treated as the dependent variables. In the second breakout, the functional relationships are reversed, te., the properties are the independent variable and the resins are the dependent variable. ASTM test methods by which the physical values were determined are listed. The. physical data versus resins are presented in both tabular and graphic form. 

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