Properties of Model Polyethers

Some physical properties of model polyethers are presented in tabular form below (Ref 2)... 

Crist B, Fisher C J and Howard P (1989) Mechanical properties of model polyeth-ylenes Tensile elastic modulus and yield stress, Macromolecules 22 1709-1718. 

Polyether lonophores. Isolation and identification of antibiotic X-14885A was reported.Its structure is closely related to A-23187 and cezomycin, members of the pyrrolether class of natural ionophores. Aspects of the discovery and ionophoric properties of the X-14868 complex were described. Another new naturally derived agent, CP-53607 (32), was reported to be effective t ainst coccidia and as a rumen propionic acid stimulant. The C-26 urethane analogs of monensin transported both Rb and Ca. Their antibacterial and anticoccidial activities were also reported as greater than monensin. Microbial conversion of grisorixin by Streptomyces rimosus was found to produce an inactive and detoxified product. A unified stereochemical model of polyether antibiotic structure and biogenesis was proposed. Ibtal synthesis of ionophores continued to be of interest and the unnatural enantiomer of lasalocid A was found to have similar biolc cal properties to the natural product. ... 

Saturated complex polyethers, particular polybutylenetherephtalate (PBT), are used as enginiring thermoplasts, having a good thermo- and wear stability, excellent performance. These properties allow also to apply them as a matrix material for polymer composites One of the perspective ways of effective filler-catalysts searching is kinetic study of reetherification model reaction, performed in the presence of various inorganic compoimds. The elucidation on the example of model system of the most effective filler-catalysts number allows to use them for receiving filled PBT and compare catalytic activity of filler and traditional catalysts. 

Gharles J. Pedersen, working for Du Pont, discovered that the interaction between ethers and metal ions is significantly stronger for compounds with multiple ether moieties. Such compounds are called polyethers. Pedersen prepared and investigated the properties of many cyclic polyethers, such as the following examples. Pedersen called them crown ethers because their molecular models resemble crowns. 

The model material used is a unidirectional carbon fiber-reinforced, thermoplastic polyether-etherketone (PEEK) composite with fiber diameter of = 8 fim. The fiber orientations studied are shown in Figure 1. The mechanical properties of this material are listed in Table 1. The first principal material direction, indicated by 1 in Table 1, is parallel to the fiber direction (Figure 1), the second and the third one are perpendicular to the fiber orientation. The anisotropic composite material properties were specified using the rule of mixture type equations. ... 

In most cases, a suitable molecular modification of the catalyst structure is required to obtain the desired thermoresponsive properties. Polyether and in particular PEG substituents are receiving considerable interest in this field. The present study has addressed structure-activity relationships for well-defined low molecular weight model ligands in the rhodiiun-catalyzed hydroformylation of 1-octene as benchmark reaction. Figure 3 summarizes the observed trends. 

The discriminative uptake of alkali metal cations by biological systems, through their membranes, has been an area of much interest. In the membrane, the cations must pass through a lipid bilayer of low dielectric constant and this has led to the proposition that the cation could be selectively transferred via a carrier molecule, or through a suitably donor-lined pore.7-9 As a consequence of their selective properties, the polyethers and cryptands have been investigated as speculative models for the above process and selectivity sequences have been established. 

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