Synthesis and characterization of copolymeric aliphatic–aromatic esters derived from terephthalic acid, 1,4‐butanediol, and ε‐caprolactone by physical, thermal, and mechanical properties and NMR measurements

Abstract

In this study, a series of aliphatic-aromatic poly(butylene terephthalate-co-e-caprolactone) (PBTCL) copolyesters were synthesized from various monomeric compositions of terephthalic acid (TPA), 1,4-butanediol (BDO), and e-caprolactone (CL) in the presence of tetrabutyl titanate (Ti(Obu) 4 ) and stannous octoate (Sn(Oct) 2 ) as catalysts through a combination of polycondensation and ring opening polymerization. A significant increase in the melting temperature (T m ) of copolyesters was observed by increasing the TPA/(CLþTPA) molar ratio, starting from the low end (T m 66.2 C) of pure poly-e-caprolactone PCL upward. We found that PBTCL-50, which has a TPA/(CLþTPA) 50% molar ratio and polycondensation at 260 C for 1.5 h, resulted in a proper T m of 139.2 C that facilitates thermal extrusion from biomass or other biodegradable polymers of similar T m . The number-average molecular weight (M n ) of 7.4 Â 10 4 for PBTCL-50 was determined from the intrinsic viscosity [g] by using the Berkowitz model of M n ¼ 1.66 Â 10 5 [g] 0.9 . Good mechanical properties of PBTCL-50 have been shown by tensile stretching experiment that indicates tensile strength, elongation, and Young's modulus are 11.9 MPa, 132%, and 257 MPa, respectively. Polymers with aforementioned properties are suitable for manufacturing biodegradable plastic films for downstream agricultural applications or merely for trash bag. This article reveals that the PBTCL-50 contains all five monomers with different molar ratios and characteristical linkages between each other. The novel structure was furthermore analyzed by 1 H-and 13 C-NMR spectroscopy.

Poly(butylene 2,5-furandicarboxylate-ε-caprolactone): A new bio-based elastomer with high strength and biodegradability

“…The lower reactivity of ε-caprolactone probably arises from inadequacy of diol initiator during the ringopening reaction and elimination of ε-caprolactone at high temperature during the polycondensation reaction, as also can be seen in the case of copolymers of TPA and ε-caprolactone [23]. Chemical structure and the real composition of PBFCL were confirmed by 1 H NMR analysis, as seen in Figure 2.…”

Chemical Structure and Microstructure of Poly(alkylene terephthalate)s, their Copolyesters, and their Blends as Studied by NMR

“…Modification in the solid state (SSM) is an interesting rather recent method that allows increasing the T g of this polymer without much decreasing its crystallinity . On the other hand, PBT is quite resistant to hydrolysis and the replacement of terephthalic units by aliphatic ones by copolymerization has been reported as an alternative to enhance its hydrolytic degradation or even its biodegradation . NMR has been again the technique of choice in all the above referenced works to characterize the PBT copolyesters including the precise determination of their compositions and microstructures …”

Novel Multiblock Poly(ε-caprolactone) Copolyesters Containing D-Glucose Derivatives with Different Bicyclic Structures

“…Figure S4 shows the 1 H NMR spectrum of the HO-PIS-OH prepolymer. The chemical shift occurring at 4.82 (δH 18 ) ppm belongs to the methine proton attached to the ether bond of Is in the repeating units, and 3.57 (δH 19 ′) ppm is the signal of the methine proton connected to the ether bond of the terminal Is. In the same way, the average number of repeating units (n) and M n of HO-PIS-OH can be obtained by the integral areas ratio of 4.82 and 3.57 ppm.…”

“…Poly­(ε-caprolactone) (PCL) is a semicrystalline aliphatic polyester that has been widely investigated as biomedical and packaging materials due to its biocompatibility, biodegradability, and nontoxicity. − PCL plays a major role in biodegradable polymers because of its wide miscibility with a many polymers and solubility in many organic solvents. − However, the low glass transition temperature ( T g ), low tensile strength and modulus, as well as slow degradation rate limit PCL’s practical application. − To overcome these drawbacks and preserve its biodegradability, researchers have introduced some aliphatic polyesters such as poly­(butylene succinate), poly­(ethylene succinate), and poly­(propylene succinate) into the main chain of PCL to obtain their block or random copolyesters. − Although the T g and biodegradability of PCL have been improved, the mechanical properties are still low. Some aromatic units have been used as modified units to increase the mechanical properties of PCL; , however, the biodegradability of PCL has been lowered.…”

“…15−17 Although the T g and biodegradability of PCL have been improved, the mechanical properties are still low. Some aromatic units have been used as modified units to increase the mechanical properties of PCL; 18,19 however, the biodegradability of PCL has been lowered.…”