Polyformal synthesis

H) 4.9ppm Scheme 3. Reaction Steps in Polyformal Synthesis... 

Watanabe [89] has used ultrasound in the synthesis of aromatic polyformals. Using a condensation reaction between a dihaloalkane and diphenol (Fig. 5.46) he was able to show that in the presence of ultrasound higher yields and larger molar masses were obtained. 

Isophthaloyl chloride has also been employed in block copolymer preparation. Poly(m-phenylene isophthalamide) and either poly-(ethylene oxide) or poly(dimethyl siloxane) block copol3miers have been prepared by terminating the former with isophthaloyl chloride and subsequently adding hydroxy terminated poly(ethylene oxide) or poly(dimethyl siloxane)(79). Block copolymers were also produced when a polyformal was capped with 1,6-hexandiol, and then heated in the presence of poly(tetramethylene terephthalate)(80). In another interesting application, polyesterpolyether block copolymers of poly-(ethylene terephthalate) and a number of polyglycols have been reported(Sl). Their synthesis involves esterification, catalyzed by zinc acetate/titanyl oxalate. ABA block polymer of 2-hydroxyethyl methacrylate and styrene was prepared by coupling -NH2 terminated PHEMA and isocyanate terminated polystyrene. The latter material was prepared by UV polymerization of styrene in the presence of bis(p-isocyanatophenyl)disulfide (82),... 

Table 1. Synthesis and Characterization of 4,4 -Dihydroxy-a-methylstilbene Polyformal and Polyethers... 

The synthesis of aliphatic polyformals (X) been known for many years and is relatively straightforward. As shown in equation 1, aliphatic diols can be reacted directly with formaldehyde or dialkyl formals to produce these polymers. The principal complication of the reaction occurs when the diol used contains 2, 3 or 4 carbon atoms in which case the formation of the cyclic formal is favored. Musser and Jackson have more... 

V. Masked Biphenols in the Synthesis of Polyformals and Poly(Aryl Ether)s. 

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