Polycaprolactone urethanes

Hillshafer et al. reported that aromatic polyester urethanes based on orthoph-thalic anhydride had better hydrolysis resistance than polycaprolactone urethanes, despite high acid numbers [91]. 

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. 

Poly(urethane urea)polysulfide resins consisting of polycaprolactone diol, 4,4 -methylenebis(cyclohexyl isocyanate), and bis-epithiopropyl sulfide, were prepared by Bojkova et al. (4) and used as optical lenses having good refractive index and good impact resistance/strength. 

The IPNs prepared were composed of a rubbery polyurethane and a glassy epoxy component. For the polyurethane portion, a carbodiimide-modified diphenyl-methane diisocyanate (Isonate 143L) was used with a polycaprolactone glycol (TONE polyol 0230) and a dibutyltin dilaurate catalyst (T-12). For the epoxy, a bisphenol-A epichlorohydrin (DER 330) was used with a Lewis acid catalyst system (BF -etherate). The catalysts crosslink via a ring-opening mechanism and were intentionally selected to provide minimum grafting with any of the polyurethane components. The urethane/epoxy ratio was maintained constant at 50/50. A number of fillers were included in the IPN formulations. The materials used are shown in Table I. 

Examples of high polydispersity ratios and bimodal distributions have been previously rationalized by heterogeneous reaction conditions. Tirrell et al.(19) found Mw/Mn values well over 2.0 and low molecular weight shoulders in slow, low temperature RIM polymerized urethanes based on polycaprolactone diols. Xu et al. 

However, for the pure polycaprolactone based oligomers the viscosity Increased as the molecular weight Increased and the urethane content decreased. 

Polyester polycaprolactones for injection-molded automotive panels, painted (without primer) with urethane and acrylic enamels, or water-based elastomeric coating... 

Biodegradable elastomeric poly(urethane) scaffolds have been fabricated by the inkjet technique (71). As monomers, methylene di-p-phenyl-diisocyanate, polycaprolactone diol, and N,N-bis(2-hy-droxyethyl)-2-aminoethane-sulfonic acid were used. The monomers are shown in Figure 7.4. 

As polyurethane intermediates react rapidly and stoichiometrically with each other, a system of nomenclature is widely used to describe the structure of individual block copolymers. Suppose, for example, a typical polyurethane consisted of polycaprolactone,4,4 -diphenylmethane diisocyanate, and 1,4-butane diol, present in the molar ratio 1 3 2, then such a polymer is reported as a 1 3 2 block copolymer and this represents a simple, convenient and rapid method of identifying the basic urethane polymer structure. The ratio of each component in the block copolymer has a dramatic effect on its properties, as shown by the data in Table 2.2. 

When the properties of H12MDI elastomers are compared with those of the analogous MDI series it is found that elastomers based on the aliphatic isocyanate generally had superior mechanical properties. This pattern of behaviour applies to both polyester, polyether, polycaprolactone and polybutadiene polyol-based urethane elastomers. 

PHYSICAL PROPERTIES OF URETHANES OF POLYCAPROLACTONE/TDI (MOCA CHAIN... 

The addition of carbodiimides, e.g. Staboxal PCD, which is supplied by Bayer, to poly(ester-urethanes) is one of the most effective ways to stabilize them against hydrolysis. Also the polyurethane structure can be tailored for better hydrolysis resistance through elimination or reduction of the ester groups present in the polyol. Hydrolysis resistance increases in the order of ether > polycaprolactone > polyester. Satrastab, developed by SATRA (Shoe and Allied Trades Research Association, Kettering, England), is also claimed to be an effective hydrolysis stabilizer for formulated polyurethanes in poromeric footwear materials. 

Polyurethanes (PUs), one of the most commonly used polymers for various blood-contacting biomedical applications, are generally prepared by the polycondensation reactions of diisocyanates with diols or amines [35, 36]. Reactions of diisocyanates with diols result in the formation of urethane linkages while diisocyanates reactions with amines result in urea linkages. Both aliphatic, as well as aromatic diisocyanate monomers, are commonly used for preparing polyurethane biomaterials. Examples include 1,4-butane diisocyanate (BDI), 1,6-hexamethylene diisocyanate (HDI), 4,4-dicyclohexylmethane diisocyanate (HMDI), and 4,4-diphenylmethane diisocyanate (MDl) [37]. Commonly used diols (or termed as polyols) for preparing polyurethanes includes poly ethers, polycaprolactone, and polyesters with molecular weights up to 5000 Da. 

Figure 8.4 Polyester urethane commonly employed for biomedical applications and drug delivery. The polymer is synthesized from biocompatible fragment PEGs, polycaprolactone...

B. Bogdanov, V. Toncheva, E. Schacht, L. Finelli, B. Sarti, M. Scandola, Physical properties of poly(ester-urethanes) prepared from different molar mass polycaprolactone-diols. Polymer 40 (1999) 3171-3182. 

Ferreira et al. [75] synthesized a HMA for medical use. Urethanes based on polycaprolactone diol (PCL) were synthesized by reaction of the molecule either with isophorone diisocyanate (IPD-isocyanate) or hexamethylene diisocyanate (HDI-isocyanate). Nies Berthold et al. [76] tried out an adhesive composition based on polymers or polymer blends consisting of caprolactone copolymers or caprolactone copolymers and polycaprolactone. The adhesive can be utilized as HMA for temporarily gluing together biological tissue and other materials in medicine. 

Bogart, V, John, W. C., Gibson,P. E.,Cooper, S. L. (1983), Structure- operty relationships in polycaprolactone-polyurethanes, J. Pofynt. Sci., Polym. Phys. Ed., 21,65-95. Bogdanov, B., Toncheva, V., Schacht, E., Finefli, L., Sartib, B., Scandola, M. (1999), Physical properties of poly(ester-urethanes) prepared Irom diflerent molar mass polycaprolactone-diols,Po/yraer, 40, 3171-82. 

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