Polytetrahydrofuran Tetrahydrofuran

The polymerization of tetrahydrofuran was first studied ia the late 1930s (3,4). In 1960, this work was summarized (4), and the Hterature on tetrahydrofuran polymers and polymerization has been growing ever siace. Polytetrahydrofuran with hydroxy end groups has become a large-scale commercial product, used mainly as the flexible polyether segment ia elastomeric polyurethanes and polyesters. It is commercially available under the trade names Terathane (Du Pont), Polymeg (QO Chemicals), and PolyTHF (BASF). Comprehensive review articles and monographs have been pubUshed (2,5-8). 

Of recent interest is the living cation of tetrahydrofuran. The oxonium ion with suitable counter ions is stable and exists in equilibrium with the monomer47. Bifunctional initiators were found to produce the polytetrahydrofuran dication. 

Polytetramethyleneglycol (polytetrahydrofuran) is formed by ring opening polyetherification of tetrahydrofuran. Branched polyalkyleneoxides are formed using polyfunctional alcohols such as trimethylolpropane and pentaerythrite. The products are liquids or waxes depending on the molar mass. Polyalkyleneoxides are often precursors for demulsifiers. 

A low molecular weight of polytetrahydrofuran was accidentally found in an anodic solution, when an electric current was passed through a solution of styrene with tetrabutylammonium perchlorate in tetra-hydrofuran (23), At the cathode styrene was polymerized and no copolymers were observed in either solution. A possible explanation of the initiation of polymerization can be offerend to account for the preliminary experimental results obtained. It may have been caused by interaction of the perchlorate radical formed at the anode [Eq. (11)] with tetrahydrofuran, providing an axonium ion. 

The living polymer technique has been applied recently in studies of equilibria tetrahydrofuran polytetrahydrofuran. This polymerization proceeds by a cationic mechanism (15) the propagation being described by the equation... 

This equation is applicable to such a system as liquid tetrahydrofuran-dissolved polytetrahydrofuran which was discussed in part 3 of this review. 

Summaries of the work in tetrahydrofuran polymerizations (7, 2, 3) have appeared as late as 1963. However, in the last four to five years the number of publications has been so numerous and the advances in the understanding of tetrahydrofuran polymerizations have been so rapid that it is worth reviewing again at this time. New catalysts have been reported, significant studies with old catalysts have been made, and a number of papers on the physical properties of polytetrahydrofuran have appeared. We will emphasize this new work and attempt to point out some areas where new investigations or a reinvestigation of earlier studies would be helpful. 

The monomer, commonly known as tetrahydrofuran, has the systematic name tetramethylene oxide or 1,4-epoxybutane. The polymer derived from it is as often called polytetramethylene oxide as polytetrahydrofuran. In accordance with Chemical Abstracts practice, we have chosen to use the names tetrahydrofuran (THF) and polytetrahydrofuran (PTHF). 

Bernardin, F. E. Ill Geveke, D. J. Danner, R. P., "Ternary Phase Equilibria of Tetrahydrofuran-Polystyrene- Polytetrahydrofuran," Department of Chem. Eng. The Pennsylvania State University University Park, PA, (1991). 

Tetrahydrofuran, just as other cyclic ethers, can be submitted to a cationic polymerization. It leads to polytetrahydrofuran (PTHF). Schematically, this can be expressed as follows ... 

Unfortunately, films formed by 25 d are still quite tacky which make them unsuitable for these applications. Visualization of air flow over objects such as aircraft requires materials which provide a smooth, abrasive resistant surface. With this in mind, the cationic chain end of 19 (see Scheme 1) was reacted with tetrahydrofuran resulting in polythionylphosphazene-h-polytetrahydrofuran block copolymer (30 and 31) [46] ... 

Unfortunately, DMC catalysts are not efficient for EO polymerisation, and it is practically impossible to obtain PO-EO block copolymers with this catalyst. Acidic catalysts are not used on an industrial scale for alkylene oxide polymerisation due to the formation of substantial amounts of cyclic ethers as side products. Acidic catalysts are used industrially only for the synthesis of polytetrahydrofuran polyols or, to a lesser extent, for tetrahydrofuran - alkylene oxide copolyether polyol fabrication (see Sections 7.1, 7.2 and 7.3) Other catalysts have a minor importance for large scale polyether polyol production. 

Polytetrahydrofuran (PTHF) is a polyether obtained by cationic ring opening polymerisation of tetrahydrofuran (THF), a five membered cyclic ether ... 

The melting temperature of polytetrahydrofuran is ca. 43°C, and its glass transition temperature is ca. — 86°C whereas polystyrene is usually an amorphous polymer at its glass transition temperature of 90°C. Furthermore, the surface tension of polytetrahydrofuran is slightly lower than that of polystyrene. Thus, styrene-tetrahydrofuran is an interesting block copolymer. This paper presents the results of morphological, crystallization, and some surface chemical studies of this block copolymer. 

Materials. An AB block copolymer of styrene and tetrahydrofuran (ST) and an ABA block copolymer of styrene-tetrahydrofuran-styrene (STS) were synthesized by the ion-coupling reaction between the living ends of polystyryl anions and polytetrahydrofuran cations as reported previously (3, 4). To re-... 

Synonyms Poly (polytetrahydrofuran carbonate) diol Tetrahydrofuran, compd. with carbonic acid Classification Polymer... 

Terminations in tetrahydrofuran polymerizations can depend upon the choice of the counterion, particularly if the reaction is conducted at room temperature. In many reactions the chain continues to grow without any considerable chain termination or transfer. This produced the term living polytetrahydrofuran. Thus, in polymerizations of tetrahydrofuran withPFe or SbFe counterions, the molecular weights of the products can be calculated directly from the ratios of the initiators to the monomers. The molecular weight distributions of the polymers from such polymerization reactions with PFe and SbF6 , however, start out as narrow, but then broaden. This is believed ... 

A living cationic polymerization of tetrahydrofuran, using BH3 as the initiator in the presence of epichlorohydrin and 3,3-bis(chloromethyl)oxacyclo-butane [348], results in formation of block copolymers. Two types form. One is an A—B type. It consists of polytetrahydrofuran blocks attached to blocks of poly(3,3-bis(chloromethyl)oxacyclo-butane). The other one is an A— AB— B type [348]. 

Polytetrahydrofuran (polytetramethylene ether, PTHF) n, A type of polycol made from tetrahydrofuran by ring opening, have the mer [-CH2(CH2)3-0-] and -OH end groups, with low to moderate molecular weights. These polymers have long been used as pre-polymers for polyurethane elastomers. 

Details of the manufacture of polytetrahydrofuran have not been disclosed. Because of the stability of the 5-membered ring in tetrahydrofuran, combinations of Lewis acids with water are not very effective initiators. More active cationic initiators are preformed carbonium salts (e.g., (C6Hs)3C SbCl6") and oxonium salts (e.g., (C2H5 )30 BF4"). The mechanism of reaction is thought to be fundamentally similar to that given above (Section 8.4.5) for the polymerization... 

GE2 Geveke, D.J., Bemardin, F.E., aM Darmer, R.P., Ternary phase equilibria of tetrahydrofuran-polystyrene-polytetrahydrofuran, J. Appl. Polym. ScL, 50, 251, 1993. 

Figure 4. Effect of halide on conversion (%) to polytetrahydrofuran (PTHF) in reactions of tetrahydrofuran with allyl halides and AgPFc...

The promise of large-scale low-cost fermentations from renewable resources, especially corn, has spurred interest in the United States to develop chemical production for large-volume chemicals using bio-based processes. Succinic acid can be converted by hydrogenation to 1,4-butanediol, which has a world market in excess of 500,000 metric tons. Butanediol is used to produce polybutylene terephthalate (PBT) resins that have desirable mechanical and thermal properties and are a high-performance version of polyethylene terephthalate resins (PET). Also, 1,4-butanediol is a precursor of tetrahydrofuran, which can be polymerized to polytetrahydrofuran (PTHF). Gamma butyrolactone (GBL) can also be derived from 1,4-butanediol, and much of GBL is used to manufacture the solvent N-methyl-2-pyrrolidone (Szmant 1989). 

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