Synthesis of Poly(ethylene terephthalate)‐block‐Poly(tetramethylene oxide) Copolymer by Direct Polyesterification of Reactive Oligomers

Abstract

The object of this study was the synthesis of thermoplastic elastomer compounds by direct copolyesterification of reactive oligomers of poly(ethylene terephthalate) (PET) and of poly(tetramethylene oxide) (PTMO). PET was glycolysed to synthesise hydroxytelechelic oligomers of PET. Commercially available hydroxytelechelic PTMO was modified to synthesise carboxytelechelic oligomers. The chemical structures of these oligomers were investigated by 1H NMR and size exclusion chromatography. Multiblock poly(ester‐ether) was then obtained by polyesterification of the hydroxytelechelic and carboxytelechelic oligomers, using different catalysts and different reaction conditions. The best stoichiometric ratio was determined to lead to the highest Mn. The chemical structure of the synthesised poly(ester‐ether) was investigated by size exclusion chromatography and 1H NMR. The thermal and thermomechanical behaviour of the synthesised poly(ester‐ether) was investigated by differential scanning calorimetry and by dynamic mechanical analysis, and showed a thermoplastic elastomer behaviour. This product could also be an interesting way of chemically recycling PET waste.Polyesterification of hydroxytelechelic PET with carboxytelechelic PTMO.magnified imagePolyesterification of hydroxytelechelic PET with carboxytelechelic PTMO.

Chemical recycling of poly(ethylene terephthalate). Application to the synthesis of multiblock copolyesters

“…The PET oligomer has an average molecular mass of 1360 g·mol -1 , with an average polymerization number ( --DP n ) of 13.6. In these conditions, the molar weight of the obtained glycosilation products were lower than the products reported in the literature (about 1450 g·mol -1 [35] and 1800 g·mol -1 [36]), these values were obtained during the PET glycolysis with the ethylene glycol, using dibutyl tin oxide as the catalyst. The PET oligomer is soluble only in few solvents, for this reason, it is used in the molten state for further polyaddition.…”

“…This reaction of depolymerization is described in Figure 1. As described in several previous studies [32,35,36] the PET glycolysis products are $, '-hydroxyl oligomers. Indeed, different SEC analysis, 1 H NMR spectroscopy, and matrix-assisted laser desorption ionization time-of-flight mass spectrometry was established; these studies show a good correlation in the determination of hydroxyl end groups and molecular weights below 4000 g·mol (2) where I x ppm represents the integral value of the peak centered at x ppm.…”

“…To the best of our knowledge, no one has ever been used BHET as diol for the PET glycolysis. Similarly, several studies have been carried out on the reaction of PET and ethylene glycol for the synthesis of hydroxytelechelic oligomers of PET [34][35][36] which were mainly used for producing unsatured polyester resins [34,35] and very few polycondensations have been carried out by using hydroxytelechelic oligomers of PET with !-caprolactone [37]. Copolyesters with PET and !-caprolactone units are mainly synthesized by polycondensation of dimethyl terephthalate, ethylene glycol and !-caprolactone [38], or by transesterification in copolyester blend [39,40].…”

Comportamento reológico do Bio-PE e do PCL na presença do PEgAA e PEgMA

“…De acordo com a literatura [26][27][28][29], grupos hidroxila podem reagir com grupos carboxila, via policondensação, para formar poliésteres, essa reação é capaz de gerar um grupo éster, onde a carbonila do ácido acrílico passa a compor esse grupo. Estando presente, essa reação contribui para aumento do peso molecular e então do torque dos sistemas PCL/PEgAA.…”

Recycling of poly(ethylene terephthalate) – A review focusing on chemical methods

“…Saint-Loup and co-workers also used ethylene glycol in reactive extrusion to produce low molecular weight oligomers (1450+1800 g·mol -1 ) without quantification of their yields for synthesis of PET-polycarbonate polyesters. However, these oligomers had to be separated and purified for further processing, since the crude reaction product consisted of a heterogeneous mixture of BHET-analoga [215][216][217][218]. The second most common degrading agent for glycolysis was diethylene glycol.…”