Poly 1,4-cyclohexylenedimethylene copolyesters

CHDA CHDM DMCD EG IPA N NDA PCT PCTA PCTG PET PETG TMCD TPA cis/trans-1,4-cyclohexanedicarboxylic acid cis/trans-1,4-cyclohexanedimethanol dimethyl cis/trans-1,4-cyclohexanedicarboxylate ethylene glycol isophthalic acid dimethyl 2,6-naphthalenedicarboxylate 2,6-naphthalenedicarboxylic acid poly(1,4-cyclohexylenedimethylene terephthalate) dibasic-acid-modified PCT copolyester glycol-modified PCT copolyester poly(ethylene terephthalate) CHDM-modified PET copolyester c .S / ra .v-2,2,4,4-tetramethyl-l,3-cyclobutancdiol terephthalic acid... 

Another aromatic CHDM copolyester family closely related to PECT is poly(trimethylene-co-l,4-cyclohexylenedimethylene tere-phthalate) (I CT) (Figure 6.8). This random copolyester was synthesized by melt polycondensation of 1,3-propanediol, 1,4-CHDM and DMT (46). Similarly to what is observed for PECT, copolyesters with less than 35% of 1,4-CHDM units crystallize in a PTT type lattice, whereas those with higher contents crystallize in the a PCT type lattice. The thermal stability of the copolymers was found to increase with the content in 1,4-CHDM units. 

Poly(butylene-co-l,4-cyclohexylenedimethylene terephthalate) copolyesters (PBCT) (Figure 6.9) with a random microstructure have been synthesized by melt polycondensation for a range of BD/1,4-CHDM ratios between 94/8 and 23/77 (47,48). PBCT are crystalline for all compositions and display an eutectic behavior. Copolyesters with less than 25 %mol of CHDM units crystallize in a PBT like lattice whereas above 38 %mol they adopt a PCT-like lattice. PBCT copolyesters were found to be more stable than PCT and PBT at the initial stage of the thermal decomposition (49). 

If BD is replaced by 1,6-hexanediol, the poly(hexamethylene-co-1,4-cyclohexylenedimethylene terephthalate) random copolyesters... 

The large variety of polyesters or copolyesters that can be obtained with 1,4-CHDM make these products usable in a broad range of applications. Thus aliphatic polyesters and copolyesters are produced to generate biodegradable or biocompatible objects, as it is the case of poly(l,4-cyclohexylenedimethylene fumarate), with application in the manufacture of bioresorbable bone cement composites (27). Polyoxaesters of 1,4-CHDM are a new class of synthetic absorbable polyesters with potential surgical applications as suture coatings, or adhesion prevention barriers (28). 

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