Sebacate Based Polyesters

Biodegradable aliphatic-aromatic polyesters obtained from dicarboxylic acids and dialcohols are known in the literature and are com- 

Biodegradable pol5miers that can be prepared using an enz5mie catalyst are exemplified by poly(propane-l,2-diol sebacate), poly-(butane-l 3-diol-sebacate), poly(butane-2 3-diol sebacate), and poly-(pentane-2,4-diol sebacate). 

The enz)mie catalyst used in the process of preparing the biodegradable pol5mier is preferably a lipase that is hydrolase. Particularly, Candida antarctica Upase B is preferable. 

This enzyme includes the amino acid of seiine-histidine-aspar-tame (Ser-His-Asp). The enz5me may be prepared as follows, or a commercial product may be used (53). 

Preparation 4r-l Candida strains may be cultivated in a nutritive medium containing assimilable carbon and nitrogen sources, essential mineral matter, trace elements and the like under aerobic conditions, and the medium may be constructed in a conventional manner. After the cultivation, insoluble substances are removed by filtration or centrifuging to prepare a concentrated solution of liquid enzyme, and a culture solution may be subsequently evaporated or concentrated by reverse osmosis. The concentrated solution may be precipitated in a solvent capable of being mixed with salts or water, for example ethanol, or may be dried in a conventional spray manner to prepare a solid enzyme preparation. 

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As a possible application of glycerol-based polyesters, new crosshnkable polyesters were synthesized via a lipase CA-catalyzed polymerization of divinyl sebacate and glycerol, in the presence of unsaturated higher fatty acids derived from renewable plant oils [110, 111]. The curing of the polymer obtained from hnoleic or hnolenic acid proceeded via a cobalt naphthenate catalyst or thermal treatment to produce a crosshnked transparent fUm with good biodegradabiHty. 

Bio-based polyesters composed of 1,3-propanediol, sebacic acid, and itaconic acid in various ratios showed excellent SM properties after cross-linking with peroxide. could be tuned by the composition between 12 and 54"C [46]. 

A comparison of the yield stress as a function of temperature for different flexibilized epoxy resin systems is given in Fig. 6. The crystalline EP exhibit lower yield stresses than the conventional flexibilized EP. The crystalline system, based on sebacic acid even shows ductile behaviour at -80 C, whereas the adipic acid system reaches its critical yield stress limit at -70°C, and brittle failure at lower temperatures is found. Measurements of Hartwig also showed brittle fracture at cryogenic temperatures. But there also seems to be no evidence of ductile behaviour in the case of the sebacic acid polyester segments. The lowest yield stress at -100°C is exhibited by the rubberlike polymer based on sebacic acid polyester. Here too, the adipic acid polyester shows higher yield stresses, but achieves ductile behaviour at -100°C. The more rapid increase in yield stress is due to the absence of crystallinity. These results show that good low temperature flexibility may be... 

End-functional polymers were also synthesized by lipase-catalyzed polymerization of DDL in the presence of vinyl esters [103,104]. The vinyl ester acted as terminator ( terminator method ). In using vinyl methacrylate (12.5 mol % or 15 mol % based on DDL) and lipase PF as terminator and catalyst, respectively, the quantitative introduction of methacryloyl group at the polymer terminal was achieved to give the methacryl-type macromonomer (Fig. 12). By the addition of divinyl sebacate, the telechelic polyester having a carboxylic acid group at both ends was obtained. 

A 100% natural polymer based entirely on agricultural products, the polyester elastomer obtained by reacting castor oil with a castor oil derivative, sebacic acid, was the basis for the synthesis of SIN s. 

Oil-Based SINs. The SINs produced were based on a castor oil polyester-urethane and styrene crosslinked with 1 mole percent of technical grade (55%) divinyl benzene (DVB) (7). This structure may be written poly[(castor oil, sebacic acid, TDI)-SIN-(Styfene, DVB)], poly[(CO,SA,TDI)-SIN-(S,DVB)]. Benzoyl peroxide (BP) (0.48%) was used as the free radical initiator for the styrene and 1,4-tolylene-diisocyanate (TDI) was used as the crosslinker for the polyester prepolymer. A 500 ml resin kettle equipped with a N inlet, condenser, thermometer, and high torque stirrer was used as the polymerization reactor. 

Polyester-amides Polyanhydrides Polyalkylene oxamate based on P-hydroxy-l-hexanol Copolyanhydrides of sebacic and l,3-propane-bis-(4-oxybenzoate) A, B, G C, H... 

Other modifications of vegetable oils in polymer chemistry include the introduction of alkenyl functions, the study of novel polyesters and polyethers and the synthesis of semi-interpenetrating networks based on castor oil (the triglyceride of ricinoleic acid) [42], and also the production of sebacic acid and 10-undecenoic acid from castor oil [44]. Additionally, the recent application of metathesis reactions to unsaturated fatty acids has opened a novel avenue of exploitation leading to a variety of interesting monomers and polymers, including aliphatic polyesters and polyamides previously derived from petrochemical sources [42, 45]. 

The synthesis of dimeric fatty acids is based on the reaction between a fatty acid with one double bond (oleic acid) and a fatty acid with two double bonds (linoleic acid) or three double bonds (linolenic acid), at higher temperatures in the presence of solid acidic catalysts (for example montmorillonite acidic treated clays). Dimerised fatty acids (C36) and trimerised fatty acids (C54) are formed. The dimer acid is separated from the trimeric acid by high vacuum distillation. By using fatty dimeric acids and dimeric alcohols in the synthesis of polyesters and of polyester polyurethanes, products are obtained with an exceptional resistance to hydrolysis, noncrystalline polymers with a very flexible structure and an excellent resistance to heat and oxygen (Chapter 12.5). Utilisation of hydrophobic dicarboxylic acids, such as sebacic acid and azelaic acid in polyesterification reactions leads to hydrolysis resistant polyurethanes. 

In practice, esters from adipic, sebacic, and phthalic acid are frequently used as polyester plasticizers. The value of n may vary from 3 to 40 for adipates and from 3 to 35 for sebacates. Polyester plasticizers are seldom used alone. They are used in combination with monomeric plasticizers to reduce the volatility of the mixed solvents. They offer a higher resistance to plasticizer migration and to extract by kerosene, oils, water, and surfactants. Polyester plasticizers are used specially in PVC-based blends and in nitrocellulose varnishes. 

Polyesters with molar masses of a few thousand are obtained by poly-condensing ethylene glycol with adipic or sebacic acid. The polymers have low glass transition temperatures, because of the flexible ester groups, as well as low melting temperatures, and so are used as flexible segments for elastic fibers, as secondary plasticizers, as nonfatty ointment or cream bases, as well as making leather impermeable because of its water-repellent action. 

Polyesters based on ethylene glycol and sebacic or adipic acid with molecular weights of several thousand are therefore used as plasticizing segments (internal plasticization) for elastic fibers or as secondary polymer plasticizers for poly(vinyl chloride). Poly(ethylene adipate) also serves... 

Castor oil hydroxyl groups can be easily reacted with either isocyanate groups to form polyurethanes, or with carboxyl groups to form polyesters. The synthesis scheme for forming polyester-based SINs from castor oil is illustrated in Figure 22 (80). Here, sebacic acid (itself a derivative of castor oil) is reacted with... 

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]. 

Copolyester Systems.— The synthesis of modified ether-type polyesters and their applications have been reviewed. Block copolymer systems based on poly-(hexamethylene sebacate)-poly(dimethylsiloxane) have been synthesized and characterized by n.m.r. and crystallization studies. Tetramethylene sebacate-tetramethylene terephthalate random copolymers have been prepared and... 

The plasticizer can also significantly affect the lifetime of the sensor [40] e.g., polyester sebacate (PES), when used instead of classic plasticizers, i.e., DOS or NPOE, prolongs the lifetime of valinomycin-based, potassium electrodes. 

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