Aliphatic polyesters. See

For typical physical and mechanical properties of the aliphatic polyesters, see Table II. 

Aldiough they were the first step-growth polymers fully characterized, it is interesting to note that die first commercial applications of aliphatic polyesters appeared only in the late 1950s and the 1960s, widi die development of polyurediane foams and elastomers (see Chapter 5). 

Although low-molar-mass aliphatic polyesters and unsaturated polyesters can be synthesized without added catalyst (see Sections 2.4.1.1.1 and 2.4.2.1), the presence of a catalyst is generally required for the preparation of high-molar-mass polyesters. Strong acids are very efficient polyesterification catalysts but also catalyze a number of side reactions at elevated temperature (>160°C), leading to polymers of inferior quality. Acid catalysts are, therefore, not much used. An exception is the bulk synthesis of hyperbranched polyesters reported in Section 2.4.5.1, which is carried out at moderate temperature (140°C) under vacuum in the presence of p-toluene sulfonic acid catalyst. The use of strongly acidic oil-soluble catalysts has also been reported for the low-temperature synthesis of polyester oligomers in water-in-oil emulsions.216... 

Mechanical properties. See also Dynamic mechanical analysis (DMA) of polyamides, 138 of polyester LCPs, 52 of polyurethanes, 242-244 of semicrystalline aromatic-aliphatic polyesters, 45 Mechanical recycling, 208 Medical applications, for polyurethanes, 207... 

Phthalazinone, 355 synthesis of, 356 Phthalic anhydride, 101 Phthalic anhydride-glycerol reaction, 19 Physical properties. See also Barrier properties Dielectric properties Mechanical properties Molecular weight Optical properties Structure-property relationships Thermal properties of aliphatic polyesters, 40-44 of aromatic-aliphatic polyesters, 44-47 of aromatic polyesters, 47-53 of aromatic polymers, 273-274 of epoxy-phenol networks, 413-416 molecular weight and, 3 of PBT, PEN, and PTT, 44-46 of polyester-ether thermoplastic elastomers, 54 of polyesters, 32-60 of polyimides, 273-287 of polymers, 3... 

Last but not least, some of us have recently synthesized polyimide-aliphatic polyester triblock and graft copolymers in collaboration with Hedrick and his coworkers [ 97,98]. Well-defined aminophenyl or diaminophenyl end-functional polyester oligomers have been synthesized on purpose and used as end-cappers or macromonomers leading to the aforementioned triblock or graft copolymers, respectively. The polyimide-polyester copolymers so obtained proved to be highly efficient promoters of polyimide nanofoams (for more details see Sect. 4.2). 

At the end of the 1990s, BASF commercialized Ecoflex F, a completely biodegradable statistical copolyester based on the fossil monomers 1,4-butanediol (BDO), adipic acid and terephthalic acid (see Fig. 3). Ecoflex F combines the good biodegradability known from aliphatic polyesters with the good mechanical properties of aromatic polyesters. 

Completely aliphatic polyesters, made from aliphatic diacid and aliphatic diol components), are not of major industrial importance because of their low melting temperatures and poor hydrolytic stability. (Low-molecular-weight aliphatic polyesters are used as plasticizers and prepolymer reactants in the synthesis of polyurethanes see Secs. 2-12e, 2-13c-2). 

The chosen ABj monomer for the synthesis of die dendritic aliphatic polyesters Dl, D2, and D3 was bis-MPA. In the convergent growth approach, dendrons of certain generations were initially synthesized. In a final step these dendrons were coupled to the polyfunctional core molecule (see Scheme 2). To get an acceptable overall yield it is important that all reactions such as coupling, protection, and deprotection are selective and proceed in high yields since a laige number of steps are involved in the synthesis of the final dendrimers. 

Noncrystalline aromatic polycarbonates (qv) and polyesters (polyarylates) and alloys of polycarbonate with other thermoplastics are considered elsewhere, as are aliphatic polyesters derived from natural or biological sources such as poly(3-hydroxybutyrate), poly (glyc olide), or poly (lac tide) these, too, are separately covered (see Polymers, environmentally degradable Sutures). Thermoplastic elastomers derived from poly(ester—ether) block copolymers such as PBT/PTMEG-T [82662-36-0] and known by commercial names such as Hytrel and Riteflex are included here in the section on p oly (butylene terephthalate). Specific polymers are dealt with largely in order of volume, which puts PET first by virtue of its enormous market volume in bottle resin. 

Most polyesters (qv) are based on phthalates. They are referred to as aromatic-aliphatic or aromatic according to the copolymerized diol. Thus polyethylene terephthalate) [25038-59-9] (PET), poly(butyelene terephthalate) [24968-12-5] (PBT), and related polymers are termed aromatic-aliphatic polyester resins, whereas poly(bisphenol A phthalate)s are called aromatic polyester resins or polyarylates PET and PBT resins are the largest volume aromatic-aliphatic products. Other aromatic-aliphatic polyesters (65) include Eastman Kodak s Kodar resin, which is a PET resin modified with isophthalate and dimethylolcyclohexane. Polyarylate resins are lower volume specialty resins for high temperature (HDT) end uses (see HEAT-RESISTANT polymers). 

Unlike aromatics, aliphatic polyesters are generally biodegradable (see Table 9.2). More than a hundred species of bacteria are known to synthesize and store aliphatic polyesters for future use as an energy source. Examples are poly-(3-hydroxybutyrate and poly-a-hydroxyvalerate (see Figure 12.28). These... 

Nonetheless, artificial biodegradable aliphatic polyesters are still mainly based on the industrial polymerization of monomers such as glycolic acid (PGA), lactic acid (PLA), and caprolactone (PCL). (See Figure 12.29). These polyesters are applied in implants, absorbable sutures, controlled-release packaging, and degradable films and moldings. 

In topical formulations, particularly cosmetics, it is used for its softening and conditioning effect on the skin. Lactic acid may also be used in the production of biodegradable polymers and microspheres, such as poly(D-lactic acid), used in drug delivery systems.See also Aliphatic Polyesters. 

Immobilized CALB has frequently been applied in the literature as a catalyst for polymerization of aliphatic polyesters, polycarbonates, polyurethanes and their copolymers. In the present work on CALB catalyzed polymerization, the ring opening of e-caprolactone to polycaprolactone was selected as the model polymerization reaction (Figure 3.3). This model reaction has been well established in the literature [24-27] as an example of a polymerization reaction that can be successfully catalyzed by immobilized lipases (see also Chapter 4). Polymer synthesis and characterization was performed in four steps (i) polymerization (ii) separation (iii) purification and (iv) characterization. 

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