Aliphatic polyureas

Example 6. High Solids, Two-Component, Clear, Aliphatic, Polyurea Coating. This example of an aliphatic, 100% urea coating utilizes polyaspartic esters as reactive diluents (see Section 4.2.3). These compounds allow fine tuning of reactivity and physical properties and eliminate the need for viscosity-reducing solvents. 

Example 7. Solvent-Borne, One-Component, Moisture-Cure, Aliphatic Polyurea Coating. This example is of a more traditional one-component coating formulation using a volatile solvent as a diluent. The active ingredient is a modified HDI, Desmodur N-75 BA from Bayer. 

High-solids, two-component, clear, aliphatic, polyurea coating, preparation of, 252-253 High-temperature annealing, 220 High-temperature bulk polyesterifications, 61-74... 

Aliphatic iodine derivatives, 14 376 Aliphatic ketones, 14 563, 571, 581-585 reactions of, 16 331-332 Aliphatic monothiopolyesters, 23 739 Aliphatic nitration, 12 187 Aliphatic peroxyacids, 13 464 Aliphatic peroxycarboxylic acids, 18 463 Aliphatic phosphines, 19 60 Aliphatic polyamides (PA), 10 207-210 19 713, 739. See also Aromatic polyamides PA entries producers of, 10 210 properties of, 10 208, 209t Aliphatic polycarbonates, 24 703 preparation of, 19 798 Aliphatic polyketones (PK), 10 197 costs of, 10 222 properties of, 10 198t Aliphatic poly(monosulfide)s, 23 702-704 Aliphatic polyphosphonate dyes, 9 480 Aliphatic poly(polysulfide)s, 23 711 Aliphatic polysulfides, 23 734 Aliphatic polysulfoxides, 23 733 miscibility of, 23 735 Aliphatic polyurea preparation, carbonyl sulfide in, 23 625... 

An example of the use of carbon oxysulfide is the reported preparation of aliphatic polyureas. 

Uses. There may be some captive use of carbonyl sulfide for production of certain thiocarbamate herbicides (qv). One patent (38) describes the reaction of diethylamine with carbonyl sulfide to form a thiocarbamate salt which is then alkylated with 4-chlorobenzyl halide to produce 5- (4- chi o r o b enzyl) A/, A/-diethyl thiocarbamate [28249-77-6], ie, benthiocarb [28249-77-6]. Carbonyl sulfide is also reported to be useful for the preparation of aliphatic polyureas. In these preparations, potassium thiocyanate and sulfuric acid are used to first generate carbonyl sulfide, COS, which then reacts with a diamine ... 

Since the vapor pressures and cviyotatioo rates of aliphatic diamine and diisocyanate monoincni ate much higher than those of aromatic monomers, vapor deposition polymerization of aliphatic polyurea is not possible svben the substrate is kept at room temperature. The times of residence of aliphatic monomers on the substrate are loo short lo... 

T. HattorL M. lijiraa. Y. Tkkahashi. E Fukada, Y. Suzuki. M. Kakimoto, and Y. Imai. Syn thesis of aliphatic polyurea Aim by vapor depoaition polymerization and their piezocleclric properties. J/mi J. Appl. Pkys. 35 4647 (1994V... 

Multiblock systems. A somewhat similar approach is involved in the production of thermoplastic polyurethane elastomers. In this case the chain contains soft segments that are largely aliphatic polyether in nature and also hard segments that are primarily polyurea (see Chapter 27). 

Example 5. Glycolysis of Polyurethanes with Propylene Oxide after Pretreatment with Ethanolamine.55 A rigid polyurethane foam (ca. 100 g) was dissolved in 30 g ethanolamine by heating. Excess ethanolamine was stripped, leaving a clear solution. Infrared and GPC analysis indicated that the clear solution obtained contained some residual polyurethane, aromatic polyurea, aliphatic polyols, aromatic amines, and N,N -bis(f -hydroxyethyljurea. Next the mixture was dissolved in 45 g propylene oxide and heated at 120°C in an autoclave for 2 h. The pressure increased to 40 psi and then fell to 30 psi at the end of the 2-h heating period. The product was a brown oil with a hydroxyl number of485. 

Chemistry MDl-based isocyanate prepolymer, polyether and/or polyester polyols, reacts with water to form polyurea-polyurethane backbone Often MDl-based isocyanate prepolymer (some are ahphatic isocyanate based), polyether and/or polyester polyols (some contain epoxy based materials), reaction forms polyurethane backbone MD1-, TDl- and some aliphatic isocyanate-based prepolymers, polyether and/or polyester polyols, reaction forms polyurethane backbone... 

Similarly, polyureas were synthesized by the reaction of diisocyanate with aliphatic diamines carried out by three research groups, I.G. Farbenindustrie A.G., E.I. du Pont de Nemours Co. and Tokyo Institute of Technology, mentioned above. 

Polyureas and polythioureas have been synthesized by Banihashemi et al. [68] by reaction of aromatic and aliphatic amines with urea and thiourea, respectively (Scheme 14.32). In a typical procedure, a solution of 10 mmol amine, 10 mmol urea, and a small amount of p-toluenesulfonic acid (1 mmol) in 5 mL N,N-dimethylacetamide was irradiated for 7 min at 220 W and then for 8 min at 400 W in a tall beaker placed in a household microwave oven. As the result, a series of polyureas and polythioureas was obtained in good yields and with moderate inherent viscosities of 0.13-0.25 dL... 

Microencapsulation by interfacial polycondensation is a usefiil method to microencapsulate a liquid core material. Especially, polyurea and polyurethane microcapsules have been extensively investigated in various industries [209]. For example, aliphatic hexamethylene diisocyanate (HMDI) and aliphatic ethylene diamine (EDA) have been used to prepare polyurea microcapsules containing insecticide called diazinon [210]. A urea linkage is formed immediately by the reaction between an amine and an isocyanate group (see Figure 4.31), and a polyurea is synthesized by the reaction between an amine with two or more amine groups and an isocyanate with two or more isocyanate groups. 

Aliphatic or aromatic structure, as weU as liner or branched structure of the reactants, can give the microcapsule shell different porosity and permeability, which can greatly inflnence the release performances. Multifunctional reactants can help to achieve more thermal mechanical stable microcapsules since the wall is a three-dimensional cross-linked polymer network. Experiments have shown that dichlorides with less than eight carbon atoms do not prodnce qnahty polyamide microcapsules. The reason behind this is the competition between interfacial condensation and the hydrolysis reaction of dichlorides. More hydrophobic dichlorides can favor the polymerization and slow the hydrolysis. Similarly, for polyurethane and polyurea type microcapsules, polymeric isocy-nates are preferred because they might favor the formation of less permeable miCTocapsnles for the hydrolysis of isocynate groups are limited, which consequently reduced the COj release that contribute to the porosity increase of the polymer wall." ... 

Polyureas - aliphatic/aromatic (e.g., NTR-719HF, IFCI, TFS series, PA 300, UTC-40HR). 

The thermostability of these dianhydroalditol monomers may be higher than that of other aliphatic diols, which raises the Tg of the corresponding polymers. The most representative dianhydroalditol-based polymers that have been synthesized are polyesters, polycarbonates, polyethers, poly(ester carbonate)s, poly(ester anhydride)s, polyurethanes, polyureas, and poly(ester amide)s. 

The desulfurization of liquid fuels using pervaporation has been increasingly investigated over the last few years [84]. As middle distillates contain mainly aromatic sulfur compounds, desulfurization membranes tend to make use of developments in aromatic-aliphatic separation. The most frequently used membrane materials investigated for the desulfurization of liquid hydrocarbon mixtures are polyurea-polyurethane, polysiloxane. Nation, cellulose triacetate, and poly-imide [84]. In addition to a range of processes for the desulfurization of naphtha fractions patented by ExxonMobil, Transionics, and Marathon Oil, only the S-Brane process developed by W. R. Grace and Sulzer has been tested beyond the laboratory scale [84]. 

Hattori, T., Takahashi, Y., lijima, M., and Fukada, E., Piezoelectric and ferroelectric properties of polyurea thin films copolymerized by vapor deposition polymerization of aliphatic and aromatic monomers, Jpn. J. Appl. Phys., 35, 2199-2204 (1996). 

Poiyureas. Polyureas are thermosets, long used as insulators in a number of applications. Until a few years ago, ureas were available mostly as insoluble powders or highly cross-linked resins. In 1987, a vapor deposition polymerization method was successfully developed that was later applied to synthesizing polyureas (26,27). Typically, a vapor deposition technique is used by evaporating OCN—Ri—NH2 and H2N—R2—NH2 monomers simultaneously on a substrate (where Ri and R2 are various aliphatic or aromatic groups). This prevents cross-linking and allows processing thicknesses in the hundreds of nanometers to tens of micrometers. 

---