Poly THF

The cationic ring opening polymerization of oxolane (THF) or of N-substituted aziridines can be initiated by oxocarbenium salts [42]. The methacrylic ester unsaturation is insensitive to cationic sites, and polyoxolanes (poly-THF) macromonomers are obtained in good yields. 

Ion coupling of anionic and cationic living polymers is an interesting procedure for the synthesis of a well-defined block copolymer. Attempted coupling of the polystyrene anion with the poly-THF cation initiated by triethyloxonium tetrafluoro-borate yielded a block copolymer mixed with homopolymers394. The block ef-... 

Further improvements were made by carboxylating the polystyrene anion, leading to quantitative yields39S 396. Multiblock copolymers of molecular weight 500,000 consisting of sixty segments of poly-THF and polystyrene were prepared397. The effect of the molar feed ratio of the two components is shown in Fig. 7. 

In this section, it should be mentioned that star poly(tetrahydrofuran) has been prepared by coupling cationically polymerized THF with multifunctional diethylenetriamine [92] in the presence of 2,2 6,6 tetramethylpiperidine as a proton trap. When the MW of poly(THF) is 1600 seven chains are added to the triamine, when the MW is 8000 a five-arm star has been obtained. 

For polyurethane production, Donnelly [109] has carried out the synthesis of copolyurethanes based on mixtures of commercial poly(THF diol)s with glucose. Complex products resulted, which can be represented by mono- or bis(glucoside) structures. From a variety of polyol blends, solid polyurethanes were prepared which ranged from linear, soluble, weak elastomers to polymers of higher transition temperature and stiffness, low solubility, and low extension under tensile load [110]. 

Uses. Approximately 70% of the U.S. production is used to make poly(tetramethylene ether glycol) [25190-06-1] (PTMEG), also known as poly-THF, which is used in the production of urethane elastomers, polyurethane fibers (ether-based spandex), and copolyester—ether elastomers. PTMEG is also the fastest growing use (see Polyeihers, tetrahydrofuran). The remaining production is used as a solvent for the manufacture of poly(vinyl chloride) cements and coating, precision magnetic tape, a reaction solvent in the production of pharmaceuticals, and other miscellaneous uses. 

Such a procedure was successfully applied to poly(THF) leading to novel fluorinated telechelic diols precursor of a, co-diacrylates useful for coating optical fibers [13] ... 

In the 1980s, a synthetic method to produce AB block copolymers of propylene and tetrahydrofurane (THF) was proposed [29]. Polypropylene-fi/ock-poly(THF) was prepared by a combination of living polymerization of propylene with a V(acac)3 catalyst and the living polymerization of THF. Its synthesis was based on the transformation of living polypropylene chain ends to cationic ones, which initiated the living polymerization of THF. 

Alternatively, ring closure metathesis reaction is applied to the formation of cyclic polymers, although the main chain does not consist of hydrocarbon. Such a method was reported in the preparation of cyclic poly(THF) as shown in Fig. 33 [112]. Such ring-close metathesis was also applied for a preparation of catenane [113]. 

Fig. 35 Formation of cyclic polymers for the synthesis of cyclic poly(THF)...

This type of ring expansion polymerization was extended for a synthesis of multiblock copoly(ether-ester)s of poly(THF) and e-caprolactone with cyclic dibutyltin initiators [142]. Such ring expansion polymerizations of lactones to synthesize macrocyclics with spirocyclic tin initiators are shown in Fig. 42 [143],... 

The cyclic tin alkoxides have the additional advantage of offering a convenient synthetic pathway for the synthesis of macromers, triblock, and multiblock copolymers [81,82]. Macromers from l-LA [83],e-CL [84], and l,5-dioxepan-2-one (DXO) [85] have been synthesized as well as triblock poly(L-LA-b-DXO-b-L-LA) [86] and multiblock copoly(ether-ester) from poly(THF) and e-CL [87]. The polymerization proceeds by ring expansion and the cyclic structure is preserved until the polymerization is quenched by precipitation. 

The application of teleehelic compounds was carried out by ICI [97] by achieving the above reaction on poly THF hydroxytelechelic. The industrial application... 

Fig. 2. Molecular model of poly(THF diyl) (erythro form in trans-1,4-polybutadiene)551...

Poly(THF-diyl) is compatible with poly(vinyl chloride) and poly(methyl methacrylate). The combination of the two features, i.e. the coordination with the metal ion and the compatibility with some conventional resins, will find some useful applications. 

No general method for naming macromonomers has been proposed so far, so that there is a great variety of terms used. Throughout this review we always clearly state the nature of the polymeric chain and the nature of the terminal polymerizable function. For instance, co-methacryloyl-polytetrahydrofuran refers to a poly-THF chain bearing at the chain end a methacrylic ester function. 

Both methods have been used for the synthesis of poly-THF macromonomers. 

Another type of cationic initiation procedure starting from an unsaturated compound has been proposed 49). 3-Phenylallyl bromide is reacted in THF solution with AgSbF6 whereby a poly-THF macromonomer bearing a styryl residue at the chain end is formed ... 

The use of an unsaturated nucleophile to introduce into the chain end of the macromolecule a double bond has also proved successful for the synthesis of poly-THF macromonomers. The oxolane polymerization is started with any efficient initiator. When the growing chains have reached the desired length, the unsaturated deactivator is added. The reaction between the oxonium sites and the nucleophile should be fast and free of side reactions. Various unsaturated nucleophiles have been employed, e.g. p-vinylphenoxide used by Asami50). The THF polymerization was initiated with triethyloxonium tetrafluoroborate and carried out atO °C. Addition of the nucleophile (obtained by reaction of the phenol with NaH) yields the corresponding macromonomer the structure of which was characterized by various techniques ... 

The lithium salt of cinnamyl alcohol53) was also shown to be a possible deactivator for living poly-THF ... 

Even sodium methacrylate5S) can act as an unsaturated deactivator for living poly-THF. The reaction is slow but by a proper choice of the experimental conditions the macromonomers can be obtained in high yields55 without any change in molecular weight (with respect to the precursor polymer deactivated with sodium phenolate). The macromonomers thus obtained contain a methacrylic ester function at the chain end. They are identical with those prepared by cationic initiation with methacryloyl hexafluoroantimonate ... 

Amine functions readily react with oxonium sites. This reaction was used for the synthesis of graft copolymers involving reaction of living poly-THF with either poly(p-vinylpyridine) or poly(p-dimethylaminostyrene) S6K Attempts to synthesize macromonomers by a similar route were made57 but their characterization is difficult because they contain quaternary ammonium sites ... 

Triflic anhydride is an efficient initiator used in thfe living polymerization of oxolane 60), and bifunctional poly-THF oligomers can be further employed to initiate the polymerization of t-butylaziridine yielding polymers with aziridinium sites at both ends of their chain61 which can be reacted with methacrylic acid. 

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