Polycaprolactone diol

Polycaprolactone diol Polycaprolate Polycarbamic esters Polycarbonate... 

The neutral fats used in the preparation of the hydrophobic core of the several liposphere-vaccine formulations described here included tricaprin and tristearin, stearic acid, and ethyl stearate. The phospholipids used to form the surrounding layer of lipospheres were egg phosphatidylcholine and dimyristoyl phosphatidylg-lycerol. Polymeric biodegradable lipospheres were prepared from low molecular weight polylactide (PLA) and polycaprolactone-diol (PCL). 

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. 

Figure 6.6 Evolution of tan 8 during polyurethane synthesis at 110°C, at different angular frequencies,

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. 

Results qualitatively similar to those in Figure 2 were obtained with polyurethanes made from toluene dllsocyanate (TDI), BD, and 1) PCL 2000 2) a polycaprolactone diol of molecular weight 1220 (PCL 1220) 3) a polyethyleneadlpate diol of molecular weight 2000 (PEAD 2000). However, all TDI based polymers had very low stress values at 60 C. 

A polyurethane was synthesised from 1,6-hexane diisocyanate, polycaprolactone diol and a fluoroquinolone antibiotic, ciprofloxacin and characterised by size exclusion chromatography and elemental analysis. The PU was incubated in a solution of an inflanunatoiy cell-derived enzyme, cholesterol esterase or phosphate buffer for 30 days at 37C and its biodegradability determined by HPLC, mass spectroscopy and Carbon 14 radiolabel release. Analysis of the solution revealed that ciprofloxacin was released and able to inhibit the growth of Pseudomonas aeruginosa. 53 refs. 

Until recently, the polyol component was restricted to poly(oxytetramethylene)glycol (PTMG), polycaprolactone diol and to adipate ester diols such as poly(ethyleneadipate)diol. The structures of these polyols are shown in Figure 2. 

As compared to metallic compounds used as shape memory materials, shape memory polymers have low density, high shape recoverability, easy processability, and low cost. Since the discovery by Mitsubishi in 1988, polyurethane SMPs have attracted a great deal of attention due to their unique properties, such as a wide range of shape recovery temperatures (— 30°C to 70°C) and excellent biocompatibility, besides the usual advantages of plastics. A series of shape memory polyurethanes (SPMUs), prepared from polycaprolactone diols (PCL), 1,4-butanediol (BDO) (chain extender), and 4,4 -diphenylmethane diisocyanate (MDI) or toluene diisocyanate (TDI) have recently been introduced [200—202]. 

After this first example, other polyurethane systems have been successfully investigated, namely those b ed on tolylene-2,4-diisocyanate, 4,4 -methylenediphenylisocyanate, polycaprolactone diol, butene diol, butine diol. The related results will be reported in a next paper. 

Chemistry Polyurethane is produced by the reaction of a polyol with an diisocyanate (or in some instances a polyisocyanate) in the presence of catalysts. The polyols of choice are poly(propylene glycol), block copolymers of ethylene oxide (10-15%) with propylene oxide, or the newer polymer polyols (based on polymers such as polystyrene or styrene-acrylonitrile copolymer). Polyester diols such as polycaprolactone diol can be used in place of the polyether polyol in this reaction. The isocyanate of choice is a mixture of the 2,4 and 2,6 isomers of tolylene di-isocyanate in the ratio of 80 20, generally referred to as 80 20TDI. Other isocyanates such as diphenylmethane di-isocyanate (MDI), hexamethylene di-isocyanate (HMDI), and isophorone di-isocyanate (IPDI) are also used. A tin-based or amine catalyst is used to promote the reaction. Given the wide choice of reactants available, the reaction can yield foams with a range of different mechanical and thermal characteristics. 

Common SS include polyethers, polyesters and polyalkyl glycols with glass transition temperatures in the range of -70°to -30°C. Commonly used macrodiols in the PUs synthesis are polyalkyl-diols, such as polyisobutylene diol [70], polybutadiene (PBU) [20, 71], or oligo-butadiene diols [72] as well as hydrogenated polybutadiene diol [20] polyether diols polytetrahydrofuran (PTHF or PTMO) [50-52], polyethylene glycol (PEG) or (PEO) [73], polypropyleneoxide (PPO) [73] or mixed blocks of them PEO-PPO-PEO [74] and PPO-THF [54] polyester diols poly(ethylene adipate) (PEA) [4,20], poly(butylene adipate) (PBA) [20, 73], and latterly polycaprolactone diol (PCL or PCD) [75], polyalkylcarbonate polyol [20] or mixed blocks of them, for example poly(carbonate-co-ester)diol [76], poly(hexamethylene-carbonate)diol [77], as well as poly(hexamethylene-carbonate-co-caprolactone)diol [78] and a mixed block copolymer of polyether and polyester blocks PCL-b-PTHF-b-PCL [79]. Examples schemes of macrodiols are shown in Eig. 1.9. 

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. 

Figure 7.4 Methylene di-p-pheny 1-diisocyanate, polycaprolactone diol, and N,N-bis(2-hydroxyethyl)-2-aminoethane-sulfonic acid.

Polycaprolactone diol molecular weight Weight fraction MDI/BD... 

Polycaprolactone diol MW = 2000 4,4-methylene bis cyclohexyl diisocyanate (Desmodur W)... 

A representative example is the synthesis of amino acid based polyurethanes using L-tyrosine based chain extender, PEG and polycaprolactone diol as soft segments, and HDI and HMDI as diisocyanate components [38, 39]. By altering the soft and diisocyanate components, the researchers were able to prepare a number of polyurethanes with varying hydrophobicities and degradation behavior. 

Thermodegradable polyurethanes are produced from MDI, polycaprolactone diol, and 2,2-azobis(2-cyanopropanol). The polymers degrade at about 120°C, and the initial weight loss corresponds to the amoimt of azo groups in the polymer (80). When the polymerization of MDI and 1,4-butanediol is conducted in 60-crown-20 (60C20) or 36-crown-12 (36C12), respectively, polyrotaxenes are obtained consisting of polyurethane chains enclosed in the crown ethers (81). 

Dispersions can also be made by solvent-free processes. For example, isophorone diisocyanate, polycaprolactone diol, polytetrahydrofiirandiol, and dimethylolpropionic acid are reacted with an NCO OH ratio of 1.6 1 to make an isocyanate-terminated prepolymer. The prepolymer is neutralized with triethy-lamine and dispersed in water. The prepolymer is then chain extended by reacting with hydrazine hydrate. 

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. 

Woo et al. covalently linked ciprofloxacin to an aliphatic biodegradable PU based on polycaprolactone diol. ° This polymer was able to release the drug in the presence of cholesterol esterase up to 30 days while its activity against P. aeruginosa lasted for 10 days. In a preliminary cell study, this biodegradable antibiotic polymer did not show any observable effects on cell proliferation or cell membrane structure. ... 

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