Diol, poly

In a recent work of Haneda et al. [26], ACPC was reacted with several poly-diols poly(ethylene adipate), poly(tetramethyleneadipate), poly(caprolactone), aliphatic poly(carbonate) to prepare various polyazoesters. 

The significant advantage of poly(diol citrates) when compared to existing biodegradable elastomers is that the synthesis of POC is simple and can be conducted under very mild conditions. 

The mechanical properties, degradation, and surface characteristics of poly(diol citrates) could be controlled by choosing different diols and by controUing synthesis conditions such as cross-linking temperature and time, vacuum, and initial monomer molar ratio. 

Poly(Diol Citrate) Synthesis 260 1 6.3.2 Orthopedic Applications 273... 

Since the creation of the first and initial citrate-based biodegradable elastomers (CABEs), poly(diol citrate) by Yang et al. in 2004, benefited from the facile and cost-effective synthesis process, available choices of diol comonomers (from small diol molecules to macrodiols, from hydrophobic diols to hydrophilic ones, and from saturated diols to unsam-rated diols), and the multifunctionality of citric add, CABEs have stood out and become an intensively studied and used biomaterial among the family of biodegradable polymers. 

PN. Coneski, PA. Fulmer, J.H. Wynne, Thermal polycondensation of poly(diol dtrate)s with tethered quaternary ammonium biocides, RSC Adv. 2 (2012) 12824-12834. 

H.C. Zhao, M.C. Serrano, D.A. Popowich, M.R. Kibbe, G.A. Ameer, Biodegradable nitric oxide-releasing poly(diol citrate) elastomer, J. Biomed. Mater. Res. A 93 (2010) 356-363. 

M.C. Serrano, A.K. Vavra, M. Jen, M.E. Hogg, J. Murar, J. Martinez, L.K. Keefer, G.A. Ameer, M.R. Kibbe, Poly(diol-co-citrate)s as novel elastomeric perivascular wraps for the reduction of neointimal hyperplasia, Macromol. Biosci. 11 (2011) 700-709. 

H.C. Zhao, G.A. Ameer, Modulating the mechanical properties of poly(diol citrates) via the incorporation of a second type of crossUnk network, J. Appl. Polym. Sci. 114 (2009) 1454-1470. 

D. Motlagh, J. Allen, R. Hoshi, J. Yang, K. Lui, G. Ameo-, Hemo-compatibiUty evaluation of poly(diol citrate) in vitro for vascular tissue engineering, J. Biomed. Mater. Res. A lOlA (2007) 907-916. J. Dey, H. Xu, K.T. Nguyen, J. Yang, Crosslinked urethane doped polyester biphasic scaffolds potential fa- in vivo vascular tissue engineering, J. Biomed. Mater. Res. A 95A (2010) 361-370. 

Monoglyceride or fatty amide diol of a vegetable oil is initially prepared using the same procedure as described in an earlier chapter (Chapter 4). This diol has to be used as a partial replacement for poly/diols in the preparation of epoxy resin, as 100% epoxies based on this type of diol have been found to have poor performance. A general laboratory procedure with partial oil-based diol is described below. 

An exact amount of monoglyceride and poly/diol with the required amount of epichlorohydrin is placed in a three necked, round bottom flask fitted with a thermometer pocket, a condenser and a nitrogen inlet. The mixture is mixed together and refluxed for one hour. The required amount of 30% aqueous NaOH solution is added to the reaction mixture at a rate that does not change the colour of the phenolphthalein. The reaction is continued for 12-16 h by maintaining the temperature at (115 5)°C. After completion of the reaction, the product is separated by a separating funnel and washed with brine solution and water. Finally, the product is vacuum dried to obtain the required resin. The sequence of the above reactions is shown in Fig. 7.1. 

Yang, J., et al. 2006. Synthesis and evaluation of poly(diol citrate) biodegradable elastomers. Biomaterials 27(9) 1889-1898. 

Polyester is a group of polymers that contain the ester functional group in their chain. Esters are chemical compounds derived from a carboxyUc acid and a hydroxyl compound, nsnally an alcohol. Most esters are considered biocompatible since they are endogenous to the human metaboUsm and able to break down to natural metabohc products by simple hydrolysis. Elastomers composed of aliphatic polyester chains cross-linked with each other by ester bonds, snch as poly(diol citrates) and poly(glyc-erol sebacate) (PGS), have received mnch attention because they are soft, elastic, and biocompatible [26,27]. Yang et al. synthesized the first citrate-based biodegradable elastomer (CABE), poly(diol citrates), in 2004 nsing a convenient and cost-effective polycondensation reaction [26,28]. 

When designing the poly(diol citrate) bioelastomers including POC, the four rationales have been put forward as follow (1) the use of non-toxic, readily available and inexpensive monomers (2) incorporation of homogeneous biodegradable cross-links to confer elasticity to the resulting materials and leave behind some unreacted functional groups, which could be used for surface modifications (3) the availability of various diols which provided flexibility to... 

Scheme 8.20 Synthesis of poly(diol citrate) bioelastomers from citric acid and varied aliphatic diols.

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