POLY UREAS

Grassie, M. Zulfiqar, in G, Scott (ed ), Developments in Polymer Stabilisation , vol. 1, Applied Science Publishers, London, 1979, p. 197. 

Poly(ureas) can be generated from the reaction of a diisocyanate with a diamine in a step reaction as follows  

the hydrolysis of the isocyanate group can generate ureas. For example, toluene diisocyanate and water will form a polyurea by the following reaction  

Thermal decomposition of these polymers at lower temperatures occurs by the following scheme [1-3]  

For example, pyrolysis of the polyurea generated from the hydrolysis of toluene diisocyanate generated the monomer, diaminotoluene and aminoisocyanatotoluene [4]. At higher temperatures, polyureas generate NH3, CO2, HCN, CH4, some CO, and molecules related to the hydrocarbon moiety from the polymer. 

---

The Poly urea Polymer of 3,3-Dinitro-1,5-Pentane Di isocyanate and 3,3-Dinitro-1J5-Pentanediamine. 

The Post Nitrated Poly urea Polymer of 3-Nitro-3-Aza-1,5-Pentane Diisocyanate and Water. 

Diamine 108 led to 95% ee for the alkylation of l,3-diphenyl-2-propenyl acetate with 90% yield. By polycondensation with a diacid chloride or polyaddition with a diisocyanate, this ligand led, respectively, to an insoluble poly(amide) 109 or poly(urea) 110 with excellent yields. Poly(amide) 109 gave a better ee (80%) than poly(urea) 110 (38%), albeit with a lower conversion (respectively, 38 and 72%), when they were used as palladium hgands... 

Like coumarin derivatives, phenindione, a compound of the indandione class, acts by altering biosynthesis of coagulant proteins in the liver. It is used for preventing and treating thrombosis, thrombophlebitis, and thromboembolism. However, because of a number of side effects such as poly urea, polydipsia, tachycardia, and others, it is rarely used in practical medicine. Synonyms of this drug are pindone, bindan, gevuUn, indan, phenyhne, and rectadione. 

Wagner et al. (3) prepared elastomeric materials consisting of biodegradable poly(urea-urethanes), (II), containing microintegrated cells that were useful as pulmonary valves, vocal chords, and blood vessels. 

Crosslinked poly(urea-urethane)s consisting of tris(4-isocyanatophenyl)-methane, trimethylolethane, and 4,4 -methylenebis(3-chloro-2,6-diethyl-aniline) were prepared by Rukavina et al. (2) and used in optical lenses. Polycaprolactone diol derivatives were also prepared by Rukavina et aL (3) and used in optical lenses. 

Several poly(urea urethane) oligomers 28 (Figure 12) were prepared by one-component polycondensation of iV-(hydroxyalkyl)-2 -oxo-1,3-diazepane-l-carboxamides, which act as intramolecular blocked isocyanates <2005PLM 1459>. These oligomers are semicrystalline materials and their melting points show the odd/even effect observed earlier for [ ]-polyamides, [ ]-polyurethanes, poly(ester amide)s, and poly (amide urethane)s. Further analysis showed that the polymers are stable up to ca. 205-230 °C, the polymers with the lower number of methylene groups in the amino alcohol decomposing at the lowest temperature. 

Diols are predominantly used for chain extensions to give a product with only urea bonds. The progress is similar to the formation of the poly(urea-urethane), but with only urethane bonds. See Figure 2.32. 

Figure 12. Plots of log Abcrb (upper panel) and ( b — 1) (lower panel) against temperature. Data were evaluated at an extension rate of 1 min 1 and are for poly(urea-urethane) and polyurethane elastomers (87).

TABLE 1. Reagent variations in preparing poly(urea-urethane) derivatives using polyethylene glycol and polypropylene glycol. 

TABLE 2. Equilibrium swelling for selected poly(urea-urethane) derivatives ... 

When the less hindered 2,4-tolylene diisocyanate is reacted with a phospholene oxide catalyst linear oligomeric carbodiimides are obtained which have been reacted with a variety of nucleophiles to give poly(ureas), poly(acyl ureas), poly(formamidines) and poly-(guanidines) by addition across the N=C=N group. Also, reaction of the oligomeric carbodiimides with acrylic or methacrylic acid affords linear polymers, which can be further polymerized by free-radical type processes. Also, reaction of the carbodiimide oligomers obtained from 2,4-TDI with adipic acid in DMF produces a polyureid. ... 

Figure 5. The change in dynamic viscosity of Halthane 87-1 segmented poly(urea-urethane) adhesive with time increases dramatically with temperature. Since the initial viscosity decreases with temperature, the plot cross through each other.

Figure 6. Because of the rapid increase in dynamic viscosity of Halthane 88-2 poly(urea-urethane) adhesive caused by a higher concentration of HMDI- aromatic diamine chain extender, the initial viscosities are difficult to determine accurately.

Figure 7. The inverse temperature dependence of initial viscosity and direct dependence of cure chemorheology for poly(urea-urethane) adhesives yield activation energies of 9-12 Kcal/mole for viscous flow and 6-8 Kcal/mole for overall cure, respectively.

Figure 8. The scatter in the loss tangent data for 87-1 poly(urea-urethane) makes identification of the onset of gelation or hard segment vitrification impossible. Although we have drawn peaks in some of the isotherms. Statistical fits do not justify them.

Table VI contains the general properties for 50-60% HARD SEGMENT polymers. This table contains polymers which have been developed in the past such as the Polyurethanes in the 55 to 65 Shore D hardness (Fascia materials), as well as Poly(urea-urethanes) which are more recent developments. This hard segment range also covers 65 to 75D intermediate modulus materials which are in reality toughened plastics. The raw materials prices are for comparison purposes.

---