Amine-Terminated Polyols

This reaction is reported to proceed at a rapid rate, with over 25% conversion in less than 0.001 s [3]. It can also proceed at very low temperatures, as in the middle of winter. Most primary substituted urea linkages, referred to as urea bonds, are more thermally stable than urethane bonds, by 20-30°C, but not in all cases. Polyamines based on aromatic amines are normally somewhat slower, especially if there are additional electron withdrawing moieties on the aromatic ring, such as chlorine or ester linkages [4]. Use of aliphatic isocyanates, such as methylene bis-4,4 -(cyclohexylisocyanate) (HnMDI), in place of MDI, has been shown to slow the gelation rate to about 60 s, with an amine chain extender present. Sterically hindered secondary amine-terminated polyols, in conjunction with certain aliphatic isocyanates, are reported to have slower gelation times, in some cases as long as 24 h [4]. 

Aromatic amine-terminated poly(tetrahydrofuran) — 650 MW Amine chain extender —4,4 -methylene bis(3-chloro-2,6,-diethyl aniline) Note the amine chain extender must be melted into the polyol at 160°C for 3 hrs under stirring, until completely melted. Once cooled, the chain extender remains liquid in the polyol. 

Polybutadienes, polycaprolactones, polycarbonates, and amine-terminated polyethers (ATPEs) are shown in Scheme 4.4 as examples of other commercially available polyols. They are all specialty materials, used in situations where specific property profiles are required. For example, ATPEs are utilized in spray-applied elastomers where fast-reacting, high-molecular-weight polyamines give quick gel times and rapid viscosity buildup. Polycarbonates are used for implantation devices because polyuredtanes based on them perform best in this very demanding environment. Polycaprolactones and polybutadienes may be chosen for applications which require exceptional light stability, hydrolysis resistance, and/or low-temperature flexibility. 

An amine-terminated poly ether (ATPE) is prepared as follows. Charge poly(tetramethylene oxide) diol (PolyTHF 1000, BASF, 75.96 g, 0.0759 m) to a 500-mL three-neck round-bottom flask fitted with a thermocouple, a mechanical stirrer, and a vacuum port. Add tert-butylacetoacetate (24.04 g, 0.1582 m) and apply vacuum. Heat at 175° C for 4 h, Fourier transform infrared (FTIR) analysis should indicate complete loss of the polyol OH absorption at 3300 cm. The room temperature viscosity of the product should be about 520 mPa-s. React this acetoacetylated product (85.5 g, 0.0649 m) with cyclohexylamine (14.5 g, 0.1465 m) at 110° C under vacuum for several hours. Cool the resultant cyclohexylaminocrotonate poly ether product to room temperature (1790 mPa-s at room temperature). 

If no polyol is used and only amine-terminated polyethers with a diamine chain extender are employed, a polyurea RIM system is obtained. 

Thermoset polyurethanes are cross-linked polymers, which are produced by casting or reaction injection molding (RIM). For cast elastomers, TDI in combination with 3,3,-dichloro-4,4,-diphen5lmethanediamine (MOCA) are often used. In the RIM technology, aromatic diamine chain extenders, such as diethyltoluenediamine (DETDA), are used to produce poly(urethane ureas) (47), and replacement of the polyether polyols with amine-terminated polyols produces polyureas (48). The aromatic diamines are soluble in the polyol and provide fast reaction rates. In 1985, internal mold release agents based on zinc stearate compatibilized with primary amines were introduced to the RIM process to minimize mold preparation and scrap from parts tom at demold. Some physical properties of RIM systems are listed in Table 7. 

Of course the polyether polyol having terminal hydroxyl groups is not inert in propoxylation reactions. It was observed experimentally that, due to the presence of primary hydroxyl groups in all solid polyols, PO reacts preferentially with the solid polyol and not with the polyether which generally has only secondary hydroxyl groups. On the other hand, the superior reactivity of short chains, as compared with long chains, is another element which makes PO react preferentially with the solid polyol. For example, in the presence of amines used as catalysts, the polyether reacts with only 10-15% of the total PO used for synthesis. 

Synonyms Polyether polyol, flexible Polyether polyol, flexible, amine-terminated Polyether polyol, rigid Polyol, flexible Polyol, flexible, amine-terminated Polyol, rigid Polyoxypropyleneamine Polyoxypro-pylene triol... 

These amine-terminated polyols (Jeffamines) are high molecular weight polyamines of the following structure ... 

These amine-terminated polyols are available under the trade name Jeffamines with various molecular weights such as Jeffamine D-2000 (difunctional), Jeffamine T-3000 (trifunctional), Jeffamine T-5000 (trifunctional). 

This method is quite easy and rapid however, it leads to an altered saccharide, the reducing sugar being transformed into a linear polyol amine derivative. Therefore, it is rather applied to oligosaccharides since at least, the terminal sugar is preserved. 

Yeakey (55) described an improved method for preparation of polyoxyalkylene-polyamines that involved a reductive animation of polyoxyalkylene-polyols in the presence of a nickel-copper-chromium catalyst. When the poly(alkylene oxides)s in combination with ammonia and hydrogen were contacted with the catalyst at elevated temperatures (200-250°C) under pressure (2000-4000 psi 13.78 to 27.56 MPa), yields of the corresponding diamine, which was predominantly primary in nature, improved over that of other known processes. In addition, the process provided for the amination of higher molecular weight polyols than was possible before. Primary amines were the main reaction product when polyols with terminal, secondary hydroxyl groups were used. For this reason, it was preferred that poly-... 

The complete formulation of the RIM product includes polyol, isocyanate, chain extender, dispersed gas or blowing agent, surfactant to help control the gas cell dispersion in the elastomer, tin catalyst to accelerate the polyurethane formation (not needed with the amine-terminated polyethers), and fillers that may be of the reinforcing type. The most widely used rein-... 

Reaction of these polyols with an excess of isocyanate yields isocyanate terminated materials which are then chain extended by an amine such as hydrazine (NH2NH2) or ethylenediamine. The fibre is usually spun from solution in dimethylformamide. 

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