Polycaprolactones polymers

Copolymers of S-caprolactone and L-lactide are elastomeric when prepared from 25% S-caprolactone and 75% L-lactide, and rigid when prepared from 10% S-caprolactone and 90% L-lactide (47). Blends of poly-DL-lactide and polycaprolactone polymers are another way to achieve unique elastomeric properties. Copolymers of S-caprolactone and glycoHde have been evaluated in fiber form as potential absorbable sutures. Strong, flexible monofilaments have been produced which maintain 11—37% of initial tensile strength after two weeks in vivo (48). 

Endodontic points based on synthetic polymers are also available. One relatively new material is supplied as Resilon, manufactured by the Penton Clinical company, USA [15], and comprises a blend of polycaprolactone polymer with small amounts... 

Averous L., Moro L., Dole R, Fringant C., Properties of thermoplastic blends Starch-polycaprolactone, Polymer, 41, 2000, 4157-4167. 

Fukushima K, Tabuani D, Abbate C, Arena M, Ferreri L (2010) Effect of sepiolite on the biodegradation of poly(lactic acid) and polycaprolactone. Polym Degrad Stab 95 2049-2056... 

Tone, Polycaprolactone polymers. Union Carbide Corp. 

Narkis, M., Sibonc-Chaouat, S., Shkolnik, S. and Bell, J.P. (1985) Irradation effects on polycaprolactone. Polymer, 26, 50-54. 

Eschbach, F.O. and S.J. Huang, Hydrophilic-hydrophobic binary systems polv(2-hydroxyethyl methacrylate) and polycaprolactone. Polymer Preprints, 34 (1993) 848-849. 

V. V. Antic, M. V. Pergal, M. N. Govedarica, M. P. Antic and J. Djonlagic, Copolymers based on poly(butylene terephthalate) and polycaprolactone-block-polydimethylsiloxane-block-polycaprolactone, Polym. Int., 59 796-807, 2010. 

Avernous, L., Moror, L., Dole, P., and Fringant, C., (2000) Properties of thermoplastic blends starch-polycaprolactone. Polymer, 41 4157-4167. 

Shin BY, Lee SI, Shin YS, Balakrishnan S, Narayan R. Rheological, mechanical and biodegradation studies of blends of thermoplastic starch and polycaprolactone. Polym Eng Sci 2004 44 1429-38. 

Otey, F. H., Mark, A. M., Mehltretter, C. L., and Russell, C. R., 1974, Starch-based film for degradable agricultural mulch. Ind. Eng. Chem., Prod. Res. Develop. 13 90-92. Averous, L., Moro, L., Dole, P., and Fringant, C., 2000, Properties of thermoplastic blends starch-polycaprolactone. Polymer 41 4157-4167. 

Other simple tests include the soil burial test used to demonstrate the biodegradabiUty of polycaprolactone (25), following its disappearance as a function of time, and the clear 2one method which indicates biodegradation by the formation of a clear 2one in an agar medium of the test polymer or plastic as it is consumed (26). The burial test is still used as a confirmatory test method in the real-world environment after quantitative laboratory methods indicate bio degradation. 

Other blends such as polyhydroxyalkanoates (PHA) with cellulose acetate (208), PHA with polycaprolactone (209), poly(lactic acid) with poly(ethylene glycol) (210), chitosan and cellulose (211), poly(lactic acid) with inorganic fillers (212), and PHA and aUphatic polyesters with inorganics (213) are receiving attention. The different blending compositions seem to be limited only by the number of polymers available and the compatibiUty of the components. The latter blends, with all natural or biodegradable components, appear to afford the best approach for future research as property balance and biodegradabihty is attempted. Starch and additives have been evaluated ia detail from the perspective of stmcture and compatibiUty with starch (214). 

Thermoplastic polyurethane elastomers have now been available for many years (and were described in the first edition of this book). The adipate polyester-based materials have outstanding abrasion and tear resistance as well as very good resistance to oils and oxidative degradation. The polyether-based materials are more noted for their resistance to hydrolysis and fungal attack. Rather specialised polymers based on polycaprolactone (Section 25.11) may be considered as premium grade materials with good all round properties. 

Examples shown in this chapter are for PMMA. Other polymers can be separated as well. The polymers separated so far (1,2) include polystyrene, poly(a-methylstyrene), polycaprolactone, polycarbonate, poly(hexyl isocyanate), polytetrahydrofuran, poly (vinyl methyl ether), and polyvinylpyrrolidone. 

Commercial end functional polymers have been converted to alkoxyamincs and used to prepare PKO-Worri-PS.040 The hydroxyl group of alkoxyamine 284 was used to initiate ring-opening polymerization of caprolactonc catalyzed by aluminum tris(isopropoxide) and the product subsequently was used to initiate S polymerization by NMP thus forming polycaprolactone-Wodr- P8.641 The alternate strategy of forming PS by NMP and using the hydroxyl chain end of the product to initiate polymerization of caprolactonc was also used. 

Chang, R. K., Price, J., and Whitworth, C. W., Control of drug release rate by use of mixtures of polycaprolactone and cellulose acetate butyrate polymers. Drug Dev. Ind. Pharm.,... 

Considering the high hydrophobicity of the palmitoyl side chain and the rigidity of the polymer backbone, we assumed that poly(N-palmitoylhydroxyproline ester) would degrade somewhat more slowly than poly (lactic acid) or polycaprolactone. In order to confirm this hypothesis, a series of long-term stability and degradation studies have been performed over the last 2 years at MIT (22). 

Aliphatic polyesters based on monomers other than a-hydroxyalkanoic acids have also been developed and evaluated as drug delivery matrices. These include the polyhydroxybutyrate and polyhydroxy valerate homo- and copolymers developed by Imperial Chemical Industries (ICI) from a fermentation process and the polycaprolactones extensively studied by Pitt and Schindler (14,15). The homopolymers in these series of aliphatic polyesters are hydrophobic and crystalline in structure. Because of these properties, these polyesters normally have long degradation times in vivo of 1-2 years. However, the use of copolymers and in the case of polycaprolactone even polymer blends have led to materials with useful degradation times as a result of changes in the crystallinity and hydrophobicity of these polymers. An even larger family of polymers based upon hydroxyaliphatic acids has recently been prepared by bacteria fermentation processes, and it is anticipated that some of these materials may be evaluated for drug delivery as soon as they become commercially available. 

All liposphere formulations prepared remained stable during the 3-month period of the study, and no phase separation or appearance of aggregates were observed. The difference between polymeric lipospheres and the standard liposphere formulations is the composition of the internal core of the particles. Standard lipospheres, such as those previously described, consist of a solid hydrophobic fat core composed of neutral fats like tristearin, whereas, in the polymeric lipospheres, biodegradable polymers such as polylactide or polycaprolactone were substituted for the triglycerides. Both types of lipospheres are thought to be stabilized by one layer of phospholipid molecules embedded in their surface. 

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