Poly alky lene ether

Not all copolymers which are produced by step-growth processes are random in nature. Block copolymers are also of major interest. An example of the synthesis of elastic polyurethane libers was given in Section 1.5.4. Block and graft copolymers of polysiloxane-poly(alky lene ethers) with segments like 5-9 are used as surfactants in the production of polyurethane foams with uniform cell sizes. 

N. G. Gaylord, eA., Poly ethers, Part III Poly alky lene Sulfides and Other Poly thioethers, Wiley-Interscience, New York, 1962, Chapts. 12-14 . 

Later extensions of this general concept were reported by Chapman et al. [169] and Frechet [54] wherein, they reversed the amphiphilic components to produce a functionalized dendron possessing a hydrophobic head and a hydrophilic tail. The Chapman dendritic amphiphiles were derived from alky lene oxide tails and BOC terminated, Denkewalter-type dendritic heads. The Frdchet amphiphiles were obtained by attaching poly(ethylene oxide) to the focal point of a hydrophobic poly(ether) dendron as illustrated in Figure 21 [170,171]. 

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