Hydroxyl terminated polyether

TPU is usually made from hydroxyl-terminated polyether or polyester diols, diisocyanates, and bifunctional chain extenders. Since the composition, the synthetic method, molecular weight, and its distribution are all changeable, there are numerous types of TPUs available, and their prices and properties vary significantly. 

The cationic ring-opening polymerization of epichlorohydrin in conjunction with a glycol or water as a modifier produced hydroxyl-terminated epichlorohydrin (HTE) liquid polymers (1-2). Hydroxyl-terminated polyethers of other alkylene oxides (3 4), oxetane and its derivatives (5 6), and copolymers of tetrahydrofuran (7-15) have also been reported. These hydroxyl-terminated polyethers are theoretically difunctional and used as reactive prepolymers. 

Carbon-13 NMR spectra. A carbon-13 NMR spectrum of HTE polymer (Rn S 500) is shown in Figure 3. The carbon-13 NMR spectra of HTE polymers show the carbon chemical shifts at 79.3 and 72.7 ppm for the backbone and the terminal methine carbons respectively, at 43.9 and 46.2 ppm for the backbone and the terminal chloromethyl carbons, respectively, and in the range of 69.7-72.0 ppm as a multiplet for the methylene carbon. It is a characteristic feature of hydroxyl-terminated polyethers that the terminal carbon exhibits a up-field shift due to the substituent effect of the hydroxyl group, whereas the (0 carbon(s) to the terminal hydroxyl group exhibits a down-field shift (Table III). The terminal methine carbon also suggests that the hydroxyl groups are predominantly secondary. 

A polyurethane is fonned by reacting a hydroxyl-terminated polyether or polyester with an isocyanate. An example in commercial practice is the reaction of toluene diisocyanate and polypropylene glycol (PPG) to produce one of the most common forms of polyurethane (see Figure 2.6). 

Polyurethanes (PU) are a special class of polymers containing the urethane group, (—NH-CO-O-), commonly prepared by a condensation reaction between a diisocyanate and a diol, such as hydroxyl terminated polyether or polyester ... 

The first silicone surfactants were prepared by reaction of alkoxy-functional silicones with hydroxyl terminated polyethers using the transetherification reaction [7] ... 

Polyols used for the above foams include polyether polyols having a molecular weight of 2,000 to 8,000 and a functionality of two or three. Primary hydroxyl-terminated polyether polyols are preferably used. Chain extenders or crosslinkers are also used with the polyether polyols for the purpose of forming hard segments in the resulting elastomer foams. 

Other types of adducts are formed by reacting hydroxyl-terminated polyethers or polyesters with TDI. When these polyols are reacted at an NC0 0H ratio of 2 1, these adducts, also referred to as prepolymers, have the schematic structure, depending upon the functionality of the polyol, shown in Figure 1. 

The principle of formation of segmented or block copolymers (see Section 4.4.5) has also been applied to polyesters, with the hard segment formed from butanediol and terephthalic acid, and the soft segment provided by a hydroxyl-terminated polyether [polytetramethylene either glycol (PTMEG)] with molecular weight 600-3000. 

Overall functionality 2.5, and containing primary hydroxyl terminated polyethers (1,4-Butanediol)... 

HHV high calorific value HTE hydroxyl terminated polyether... 

Kim H, Lim C, Hong S-I (2005) Gas permeation properties of organic-inorganic hybrid membranes prepared frran hydroxyl-terminated polyether and 3-isocyanatopropyltriethoxysilane. J Sol Gel Sci Technol 36(2) 213-221... 

Aft r a low productive decade, the Mobay Corp. was formed by Bayer and Monsanto for the production of polyurethanes in the U.S. in 1953. However, the first polyester-based polyurethane foam disintegrated in humid air and could not compete with rubber latex foam. This difficulty was overcome by the use of hydroxyl terminated polyethers instead of polyesters. 

Polyurethanes are crosslinked in different ways depending on the choice and stoichiometry of reactants and reaction conditions. For example, an isocyanate-terminated trifunctional prepolymer is synthesized from a polyol and diisocyanate. The polyol may be a polyester prepolymer synthesized from a triol or a hydroxyl-terminated polyether. Further polymerization and crosslinking of the isocyanate-terminated prepolymer is achieved by reaction with a diamine... 

More recently Crosbie and Philips [85,86] investigated the toughening effect of several reactive liquid rubbers (carboxyl terminated butadiene-acrylonitrile, vinyl terminated butadiene-acrylonitrile, hydroxyl terminated polyether, polyepichlorohydrin) and an unspecified experimental reactive liquid rubber developed by Scott Bader Ltd. on two different polyester resins a flexibilized isophthalic-neopentyl glycol polyester resin, PVC compatible and an epoxy modified polyester resin, which is preaccelerated. The results of these studies are summarized as follows ... 

One of the simplest ways to introduce the crosslinks required for rubber-like elasticity is to carry out a copolymerization in which one of the comonomers has a functionality of three or higher [9,21]. This method, however, has been used primarily to prepare materials so heavily crosslinked that they are in the category of hard thermosets rather than elastomeric networks, as it has already been mentioned [11]. The more common techniques include vulcanization (addition of sulfur atoms to unsaturated sites), peroxide thermolysis (covalent bonding through free-radical generation), end linking of functionally terminated chains (isocyanates to hydroxyl-terminated polyethers, organosilicates to hydroxyl-terminated polysiloxanes, and silanes to vinyl-terminated polysiloxanes) [18],... 

Fainleib A, Hourston D, Grigoryeva O, Shantalii T, Sergeeva L. Structure development in aromatic polycyanurate networks modified with hydroxyl-terminated polyethers. Polymer, 42, 8361-8372 (2001). 

Carboxylic functional polyols can be prepared by reacting hydroxyl terminated polyethers with unsaturated acids and a free radical initiator. Also carboxylic groups can be added to poly(ester/ethers) or other hydroxy terminated polymers by reacting with dianhydrides. 

The synthesis of the poly(alkylene oxide)s for elastomers is contained in Chapter 4, Sections III. A, IV, and V. For polyurethane elastomers based on propylene oxide, the polyethers prepared are secondary hydroxyl-terminated polyethers. The secondary hydroxyl group is slower to react with isocyanate than is a primary hydroxyl (Table 3) (20). Therefore, poly(propylene oxide) diols and higher functionality polyols are often capped with ethylene oxide (see Chapter 4, Sections IV and V) to obtain the more reactive terminal, primary hydroxyl groups. 

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