Aliphatic Polyethers

For the purposes of this chapter, aliphatic polyethers are defined as aliphatic polymers which contain recurring ether groupings, 

Aliphatic polyethers may be obtained from two different classes of monomer, namely carbonyl compounds and cyclic ethers. These two types of polyether are considered separately in this chapter. 

Polymers of several aldehydes and ketones and halogenated derivatives have been prepared. As yet, only those of formaldehyde have achieved commercial importance these polymers are described in detail in the next section. 

Polymers of aldehydes are commonly termed polyacetals (or acetal resins) since their structure resembles that of polymers obtained by the acetalforming reaction between aldehydes and diols  

It may be noted that the reaction shown above can actually be used for the preparation of polymers but it does not represent a commercially used 

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Multiblock systems. A somewhat similar approach is involved in the production of thermoplastic polyurethane elastomers. In this case the chain contains soft segments that are largely aliphatic polyether in nature and also hard segments that are primarily polyurea (see Chapter 27). 

Besides being commercially referred to as polyacetal materials polyformaldehydes are also often known as polyoxymethylenes and are the simplest type of a family of aliphatic polyethers. 

Of the many other aliphatic polyethers, polythioethers and polysulphides prepared in the laboratory, some have become commercially available. Those of interest to the plastics industry are dealt with later in this chapter. 

The flexible backbone of an aliphatic polyether chain can lead to polymers with a low glass transition temperature. Providing crystallisation can be inhibited by... 

Polyacetals are among the aliphatic polyether family and are produced by the polymerization of formaldehyde. They are termed polyacetals to distinguish them from polyethers produced by polymerizing ethylene oxide, which has two -CH2- groups between the ether group. The polymerization reaction occurs in the presence of a Lewis acid and a small amount of water at room temperature. It could also be catalyzed with amines ... 

F.D. Konstandakopoulou, K.G. Gravalos, and J.K. Kallitsis, Synthesis and characterization of processible aromatic-aliphatic polyethers with quinquephenyl segments in the main chain for light-emitting applications, Macromolecules, 31 5264-5271, 1998. 

The usefulness of the PTP concept was further demonstrated by Frechet et al. [30] in a study where hyperbranched aliphatic polyethers were synthesized from a diepoxide and a tri-functional alcohol, utilizing an A2-B3 monomer concept. 

Commercially available hyperbranched polymers are Polyglycerol (aliphatic polyether polyol) and Polyethylenimine (aliphatic polyamine) both from Hyperpolymers, Boltom (aliphatic polyesters) from Perstorp and Hybrane (aromatic polyester amide) from DSM. 

A manifold of dendrimers have been presented in the literature ranging from polyamidoamine, polyfpropylene imine), aromatic polyether and polyester, aliphatic polyether and polyester, polyalkane,polyphenylene, polysilane, and phosphorus dendrimers. Combinations of different backbones as well as architectural modifications have also been presented. For example, the incorporation of chirality in dendrimers, copolymers of linear blocks with dendrimer segments (dendrons), and block copolymers of different dendrons has been described. Numerous applications have been proposed for dendrimers such as biotemplates, liquid membranes, catalysts, or in medical applications. ... 

Ahad, E. (1989) Branched hydroxy terminated azido aliphatic polyethers. 

Poly(ether-b-amide). In these particular thermoplastic elastomers the hard blocks consist of aliphatic polyamides, whereas the soft segments are formed of aliphatic polyethers. 

The fuel properties of the pyrolysis oil of an aliphatic polyether-segmented PU could be predicted by taking into account the linear and cyclic oxygenated saturated and olefinic hydrocarbon nature of the components. Elimination of the reactive and toxic diisocyanate from the pyrolysis oil of PU in a lower temperature pyrolysis step is easier in the case of polyether soft segment, because of the larger temperature difference of decomposition steps compared to that of polyester-segmented PU. 

Following the first papers of Tomalia et al. [35] and Newkome e( al. [36] in 1985 dealing with dendrimers, a large number of dendrimers have been presented in the literature ranging from polyamidoamine [38], aromatic polyethers [39] and polyesters [40], aliphatic polyethers [41] and polyesters [42], polypropyleneiraine [43], polyphenylene [44] to polysilane [45]. Copolymers of linear blocks with dendrimer segments (dendrons) and block copolymers of different dendrons have been described. 

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