Poly -urea-urethane

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 ... 

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.

Zhang RH, Yang YK, Xie XL et al (2010) Dispersion and crystallization studies of hyperbranched poly(urea-urethane)s-grafted carbon nanotubes filled polyamide-6 nanocomposites. Compos A Appl Sci Manuf 41 670-677... 

Polysaccharides. — Poly(urea-urethane)s containing 2-acetamido-2-deoxy-D-glucosyl residues in the main chain have been prepared by direct addition polymerization of 2-acetamido-2-deoxy-D-glucose and di-isocyanates. The polymers were soluble in polar solvents and exhibited good reactivity toward acetylation and very high water absorption. 

The majority of the structures is prepared from AB2 monomers by polycondensation, to result in hb polyesters, polyamides, polyethers, poly(ester amide)s, polysulfones, poly(ether ketone)s, polyphenylenes (among others), and increasingly also by polyaddition leading to, for example, poly(carbosilane)s, poly(urea urethane)s, polyarylenes, poly(ether amide)s or polythioethers, and many others [6-11, 13, 17, 21]. In particular, cycloaddition reactions offer the advantage of an often very selective and clean, high-yield reaction that is not influenced by special functionalities [33]. The relatively easy synthesis of the hb polyphenylenes described by Mullen et al. [34]. is an excellent example of this. In addition, certain cycloaddition reactions form as Hnear units nonstable intermediates, which allows the preparation of hb polymers without any linear units, which therefore exhibit formally a DB of 100% [35]. 

The synthesis of model compounds mimicking the structural characteristics of the possible subunits, and the comparison of their spectra with that of the hb polymer, represents a common method for assigning signals to subunits. This procedure, for the assignment of urea and urethane carbonyl carbon signals of a hb poly(urea urethane) synthesized from an AA (2,4-toluylene diisocyanate) and B2 B (diethanol amine) monomer [94], is shown in Figure 24.3. 

An example of this is shown in Figure 24.8, where the broadly distributed hb poly(ether amide) [134] was fractionated into molar masses of between 60000 and 700 000 g mol . The differences between the polydispersity of the hb sample directly after the one-pot synthesis, and of the individual samples obtained after its fractionation, were clearly distinguished (Figure 24.8). In aU fractionations performed on the hb polymers, independent of their chemical origin - whether polyesters, poly(ether amide)s, or poly(urea urethane)s - it was observed that the solubility had been governed by the molar mass. The question of whether this influence of molar mass is exclusive, or not, should be resolved by an analysis of the DB and the chemical structure of the single fractions. 

In addition to the DB, the fractionation process is quite heavily influenced by the different chemical nature of the byproducts, and also provides the possibility of their separation and identification. One example of the chemically controlled elution fractionation was that of a hb poly(urea urethane) this was the product of a complex AA + B2B reaction between 2,4-toluylene diisocyanate (TDI) and diethanol amine (DEA), additionally end group-modified with phenylisocyanate [94]. Whilst the fractionation of this sample led to a bimodal distribution, an analysis of the fi actions (using SEC with RI detection) showed clearly that the first peak of the distribution belonged to a low-molar-mass substance, identified by NMR and MALDI-TOF as the byproduct diphenylurea (Figure 24.9) [154]. 

Wang J, Zheng Z, Chen L, Tu X, Wang X. Glutathione-responsive biodegradable poly(urea-urethane)s containing L-cystine-based chain extender. J Biomater Sci Polym Ed 2013 24(7) 831 8. 

Direct addition pol3mieri2ation of 2-amino-2-deoxy-D-glucose and a diisocyanate (4,4 -methylene-diphenyl-l, 1 -di-isocyanate, phenyl-1,4-di-isocyanate, toluene-2,4-di-isocyanate, or butyl-1,4-di-isocyanate) yields a linear sugar-containing poly(urea-urethane) (5) having good solubility in organic solvents, unlike chitin or chitosan. ... 

MMT is a reinforcing filler in polymers such as poly(urea urethane) (Ge et al. 2000) as evidenced by the very significant increase in mechanical properties of the composite nanofibers. Unfilled polymer nanofiber mats of polyurethane (PU) (M — 150,000 g/mol) were electrospun from llwt% solution in DMAc/THF (7 3wt/wt) into nanofibers with 150nm to 410nm. The tensile properties of these mats are shown in Table 6.4, where the last digit in the nanofiber designation is the weight fraction of MMT in the polymer. Based on the WAXD patterns for the composite nanofibers, MMT appeared to be well dispersed, exfoliated, and oriented in the axial direction of the samples. 

Sahre K, Elrehim MHA, Eichhom K-J, Voit B. Monitoring of the synthesis of hyperbranched poly(urea-urethane)s by real-time Attenuated Total Reflection (ATR)-FT-IR Spectroscopy. Macromol Mat Eng 2006 291 470 76. 

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