Polycaprolactone blends

In addition to PEGA/PEEA blends, polycaprolactone (PCE) has also been investigated as a potential substrate for RPC seeding. For example, Redenti et al. have successfully cultured mouse RPCs on laminin-coated novel nanowire PCE scaffolds [143]. 

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). 

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). 

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. 

Malinconico M, Immirzi B, Massenti S, La Mantia FP, Mormile P, Petti L (2002) Blends of poly-vinylalcohol and functionalized polycaprolactone. A study on the melt extrusion and post-cure of films suitable for protected cultivation. J Mat Sci 37 4973 1978 Mallek SB, Prather TS, Stapleton JJ (2007) Interaction effects of Allium spp. residues, concentrations and soil temperature on seed germination of four weedy plant species. Appl Soil Ecol 37 233-239. doi 10.1016/j.apsoil.2007.07.003... 

A wide range of thermoplastic starch compounds have been claimed in recent years. Formulations of thermoplastic starch with linear, biodegradable polyesters, including polycaprolactone and PHBV,174 176 and with polyamides175 have been reported. Laminated structures have been claimed using thermoplastic starch or starch blends as one or more of the layers.175,177,178 The use of polymers latexes as components of thermoplastic starch blends has also been claimed.179 181 Blends with natural polymers are also claimed, including cellulose esters182,183 and pectin.184 A crosslinked thermoplastic material of dialdehyde starch and protein has been reported.185... 

There is a large body of patent literature and a growing amount of scientific literature on blends of polycarbonate with various crystallizable polyesters. The latter would include poly (ethylene terephthalate), poly-(butylene terephthalate), polycaprolactone, and certain copolyesters derived from mixtures of terephthalic acid and isophthalic acid co-reacted with 1,4-cyclohexanedimethanol (79, 80, 81,82). As shown recently, some of these mixtures form miscible blends although the polyester possesses the possibility of crystallizing. The number of patents on such systems indicates a degree of commercial interest. 

Starch can be destructured in the presence of more hydrophobic polymers such as aliphatic polyesters. Aliphatic polyesters with low melting points are difficult to process by conventional techniques such as film blowing and blow moulding. Films such as polycaprolactones (PCL) are tacky as extruded and have a low melt strength (over 130 °C). Also, the slow crystallisation of the polymer causes the properties to change with time. Blending starch with aliphatic polyesters improves processability and biodegradability. 

Polycaprolactone aliphatic polyesters have long been available from companies such as Solvay and Union Carbide (now Dow Performance Chemicals) for use in adhesives, compatibilisers, modifiers and films as well as medical applications. These materials have low melting points and high prices ( 4-7 per kg in 2005). PCL is predominantly used as a component in polyester/starch blends such as... 

The most direct way of looking at the specific interactions is by using spectroscopic measurements. Infra-red spectroscopy is the technique which has been most commonly used to study mixtures involving polymers. Studies of blends of PVC with polycaprolactone showed shifts of 4-6 cm in the carbonyl band of polycapro-lactone relative to the pure polymer but this Figure should be treated with... 

Munk and co-woricers have been concerned with the above-stated problem for some time (38, 39). In this volume (40), their attention is focused on miscible blends of polycaprolactone and polyepichlorohydrin. These authors demonstrate that to a considerable degree the probe variation problem can be mitigated by scrupulous attention to experimental details in the IGC methodology. This concern for details is required at any rate, if the high data reproducibility needed for meaningful studies of interaction in miscible polymer blends is to be attained. These details center on modified methods for coating polymers onto solid supports, on improved methods for measuring carrier gas flow rates, and on enhanced, computer-based data analyses of elution traces. Also, corrections are made for contributions to retention times from uncoated support material. More than twenty volatile probes are used by Munk, and the probe-to-piobe variations in %23, while not entirely absent, are much less apparent than they would be under standard experimental protocols. 

McClure MJ et al (2009) Electrospinning-aligned and random polydioxanone-polycaprolactone-silk fibroin-blended scaffolds geometry for a vascular matrix. Biomed Mater 4(5) 055010... 

Hakkarainen [19,36] Poly(vinyl chloride)/ polycaprolactone-carbonate blend Thermo-oxidation, hydrolysis 6-Hydroxyhexanoic acid, caprolactone PDMS-DVB... 

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