Poly oxetane

The most common application for the CROP of oxetanes is the crossHnking of coatings while only a very limited number of examples of weU-defined 

More recently, another elegant approach was demonstrated for the living CROP of oxetanes [20]. In order to prevent the occurrence of chain-transfer reactions, a nucleophilic solvent (1,4-dioxane) was used to end-cap the growing polymer chains, which resulted in chain-ends with lower reactivity. More specifically, the nucleo-philicity of 1,4-dioxane is higher compared to the oxygen atoms in the polyether. 

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Many other polyethers are used in practice either as homopolymers or in copolymers. Among these are poly(propylene glycol) or poly(propylene oxide) (the acronym PPO is used for this polymer and confusingly for other ones such as poly(phenylene oxide)) CAS 25322-69-4, poly(oxetane) or poly(oxy-1,3-propylene) CAS 25722-06-9, poly[oxy(hexyl-1,2-ethanediyl)] CAS 25639-83-2, poly(1,4-oxyphenylene) CAS 25667-40-7, poly(2,6-dimethyl-1,4-phenylene oxide) CAS 25134-01-4, poly[oxy-(1-phenyl)ethylene] CAS 25189-69-9, etc. 

It has been shown that amylose selectively includes poly(tetiahy-drofuran) or poly(6-valerolactone) fromamixture of two resemblant polyethers, i.e., poly(oxetane) and poly(tetrahydrofuran), or also a mixture of two resemblant polyesters in vine-twining pol5meriza-tion (73). The highest priority on the inclusion of amylose showed poly(tetrahydrofuran). Also a selective inclusion according to the molecular weight of a poly(tetrahydrofuran) was demonstrated (74). 

Studies of poly(oxetanes) containing the azidomethyl group, AMMO and BAMO, and the glycidyl azide polymer, GAP, reveal a mixture of hydrocarbon and oxycarbon fragments along with some NH3 and HCN [59]. Presumably IR silent... 

Thus there are many examples of PEG acting as a PTC (refer also to other contributions to the Symposium). It is of interest to inquire as to the effectiveness of other polyethers. Yamazaki and coworkers have examined the effect of various polymeric additives on the reaction between sodium phenoxide and n-butyl bromide in dioxane. Poly(oxetane), poly(tetrahydrofuran), and poly(ethyl-vinylether) were found to be ineffective, while PEG gave a rate enhancement of approximately 100. Interestingly, polyvinylpyrrolidone of several molecular weights was even more effective than PEG. ... 

Using relatively similar systems based on quaternary ammonium and quaternary phosphonium halides in conjunction with sterically hindered methyl(diphenoxy)aluminum, anionic coordination polymerization of the less reactive foiu-membered ring oxetane was shown to occur, giving low-dispeisity poly-oxetanes with M up to 17 000 g mol", owing to sttong monomer aaivation by complexation with the aluminum derivatives. 

Poly(methylene oxide) see Poly(oxymethylene) Poly(4,4-(2,7-napthalenedioxy) dibenzoic acid) Poly(oxacyclobutane) see Poly(oxytrimethylene) Poly(oxetane)s see Poly(oxytrimethylene)s Poly(oxy-2-acetoxytrimethyleneoxy-2,6-dichloro-... 

Fig. 9.15 Comparison of derived Avrami equation with experimental results. Plot of fraction crystallinity against log time, (a) Linear polyethylene fraction M = 8 X 10 (34) (b) poly(oxetane) (41) (c) natural rubber (19) (d) polyimide ODPA 1 (42) (e) poly(phenylene sulfide) (43).

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