Copolymers copolyesters Poly

The development of fumarate-based polyesters for biomedical applications started around 20 years ago. Fumaric acid is a natural metabolite involved in Krebs cycle, and is comprised of a reactive double bond available for chemically crosslinking reactions. These characteristics make fumaric acid a candidate building block for crosslinkable polymers. The first and most comprehensively investigated fumarate-based copolymer is the biodegradable copolyester poly(propylene fumarate) (PPF) (Fig. 6.8). ... 

The next two decades saw the development of new polymers such as thermoplastic PU (1961), aromatic polyamides, polyimides (1962) polyaminimides (1965), thermoplastic elastomers (styrene-butadiene block copolymers in 1965), ethylene-vinyl acetate copolymer, ionomers (1964), polysulfone (1965), phenoxy resins, polyphenylene oxide, thermoplastic elastomers based on copolyesters, poly butyl terephthalate (1971) and polyarylates (1974). 

Copolyester Single Tg II was Hybel 5556, a multiblock copolymer with poly(tetramethylene ether lycol ta hthalate soft s ment 248... 

Many random copolyesters and polyester-polycarbonates have also been prepared by ester interchange reactions in the molten state. Thus, poly(ethylene terephthalate-co -isophthalates) can be obtained by simple melt blending of PET and poly(ethylene isophthalate) (PEI) homopolyesters at 270°C. The copolymer changes gradually from a block type at the beginning of reaction to a random-type... 

Copolyesters of poly(3HB-co-3HV) have approximately the same degree of crystallinity as the homopolymer PHB and all copolymers show similar conformation characteristics as those observed for PHB [24,26,65]. They show a minimum in their melting point versus composition curve at a 3HV content of approximately 40 mol%. The apparent ability of the two different monomeric units to cocrystallize might result from the fact that the copolymers are prone to show isodimorphic behavior [21, 26, 66-70]. However, the considerable reduction of the heat of fusion upon 3HV inclusion, as reported by Bluhm et al. 

Fig. 1. Melting temperature (—and enthalpy (—, AH) of poly(8CL-co-6VL) random copolymers at different compositions, as synthesized by coordination-insertion ROP initiated with Al(OzPr)3 in toluene at 0 °C. is the molar fraction of eCL in the copolyester. (Tjjj and AH were determined by DSC at a heating rate of 10 °C/min)...

Statistical copolymerization of ethylene glycol and 1,4-butanediol with dimethyl ter-ephthalate results in products with improved crystallization and processing rates compared to poly(ethylene terephthalate). Polyarylates (trade names Ardel, Arylon, Durel), copolymers of bisphenol A with iso- and terephthalate units, combine the toughness, clarity, and proce-sibility of polycarbonate with the chemical and heat resistance of poly(ethylene terephthalate). The homopolymer containing only terephthalate units is crystalline, insoluble, sometimes infusible, and difficult to process. The more useful copolymers, containing both tere- and isophthalate units, are amorphous, clear, and easy to process. Polyarylates are used in automotive and appliance hardware and printed-circuit boards. Similar considerations in the copolymerization of iso- and terephthalates with 1,4-cyclohexanedimethanol or hexa-methylene diamine yield clear, amorphous, easy-to-process copolyesters or copolyamides,... 

Aluminum isopropoxide has been used for the preparation of block copolyesters [147, 148]. Tri-block poly(e-CL-b-DXO-e-CL) was prepared by the sequential addition of different monomers to a living polymerization system initiated with aluminum isopropoxide in THF or toluene solution [95]. An alternative route for the preparation of the tri-block copolymer was to react the diblock poly(e-CL-b-DXO) containing an -OH functionality at the chain end using a difunctional coupling agent such as isocyanate or acid chloride (Scheme 18). However, the molecular weights were low and full conversion of monomers was not achieved. 

The conpling constant of the AA BB portion of bisphenol A-neopentyl glycoltereph-thalate copolyesters (20) was determined in the presence of Pr(fod)3". The compositional tetrads of a 3,3 -dimethylbisphenol A-phenolphthalein copolyterephthalate (21) were resolved in the presence of En(fod)3 . The meso and racemic dyads of a poly(/l-snbstitnted- S-propiolactone) were distinguishable in the NMR in the presence of Eu(dpm)3". The H and NMR spectra of ethylene-vinyl acetate copolymers were assigned on the basis of two-dimensional NMR methods and lanthanide-induced shift data in the presence of Eu(fod)3". ... 

The lipase-catalyzed copolymerization of lactones often afforded random copolyesters, despite the different enzymatic polymerizability of lactones in some cases.165 167g-174 So far, the random copolymers were enzymatically obtained from combinations of d-VL-e-CL, e-CL-OL, e-CL-PDL, and OL-DDL. The formation of the random copolymers suggests that the intermolecular transesterifications of the polyesters frequently took place during the copolymerization. By utilizing this specific lipase catalysis, random ester copolymers were synthesized by the lipase-catalyzed polymerization of macrolides in the presence of poly-(e-CL).175... 

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