Biodegradable Elastomer from 2,5-Furandicarboxylic Acid and ε-Caprolactone: Effect of Crystallization on Elasticity

Abstract

Most biodegradable thermoplastic materials cannot be used as elastomers due to their relatively poor elasticity. Poly­(butylene furandicarboxylate-co-ε-caprolactone) (PBFCL) copolyesters were synthesized from 2,5-furandicarboxylic acid (FDCA), 1,4-butanediol, and poly­(ε-caprolactone) diols. The PBFCLs are susceptible to hydrolysis and enzyme degradation, and the degradation rate could be controlled by the enzymes. PBFCL40 and PBFCL50 (CL molar content) displayed high tensile strength (≥50 MPa), good elongation at break (≥1050%), and quick shape recovery like an elastomer. Although BF and CL segments were incompatible, the dynamic mechanical and rheological results excluded the possibility of microphase separation under room temperature. In situ small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS) measurements revealed the evolution of crystals during stretching. Strain-induced orientation, melting of original crystals, and formation of fibrillar crystal occurred in different strain regions, and the surviving crystals acted as the physical cross-linking points. This viewpoint was further confirmed by measuring the recoverability during cyclic tensile tests in PBFCL40 and PBFCL50 with controlled crystallinity. With controlled crystallinity, samples gained adjustable elasticity.

Tuning the Properties of Furandicarboxylic Acid-Based Polyesters with Copolymerization: A Review

“…Lanthanum(III) acetylacetonate [ 73 , 79 ], polyphosphoric acid [ 72 ], cobalt acetate [ 41 ], dibutyltin oxide [ 33 , 68 ], and EG antimony [ 48 ] have also occasionally been used. Additives, mainly Irganox 1010, a sterically hindered phenolic primary radical scavenger common in the synthesis of many types of polymers, are periodically used as antioxidants and heat stabilizers [ 48 , 56 , 58 , 85 , 91 ].…”

“…Finally, vacuum is applied, and the temperature is increased for the polycondensation step. On the other hand, polylactide (PLA) or poly(ε-caprolactone) (PCL) oligomers can be prepared separately and added directly in a two-stage polymerization reaction [ 35 , 62 , 85 ].…”

“…Block or multiblock copolymers are obtained in copolymers incorporating polyether segments, such as poly(ethylene glycol) (PEG) or poly(tetramethylene glycol) (PTMG) [ 46 , 47 , 48 , 56 , 88 , 89 , 90 , 91 , 93 , 94 , 101 ]. When ROP with CL or lactide is included in the polymerization, the outcome depends on the experimental conditions, and both random [ 49 , 54 , 85 ] and block copolymers [ 54 , 87 , 95 , 98 ] have been obtained. The structure depends mainly on whether monomers or oligomers are employed as starting products and on whether the conditions are harsh enough to cause some depolymerization of PLA or PCL oligomers, or favor transesterification reactions.…”

“…Naturally, the addition of the aliphatic moieties in the polyester reduced the thermal stability of the materials compared to the neat polyesters. However, no specific trend can be observed regarding the structure of the comonomers, except that symmetrical monomers such as succinic [ 52 , 70 , 79 , 82 ] adipic [ 50 , 72 , 73 ], and sebacic acid [ 51 ] usually lead to materials of better stability compared to ω-hydroxy carboxylic acids such as lactic acid [ 54 , 55 , 98 ], CL [ 49 , 85 , 87 , 95 ], and glycolic acid [ 76 , 77 , 92 ]. The broad range of molecular weights of the synthesized materials leaves little room for any insightful deductions.…”

“…PCL is a polyester that undergoes rapid degradation under the influence of enzymes. Biodegradable PBF- co -PCL elastomer copolymers have been reported recently, and their enzymatic degradation was evaluated [ 85 , 86 ]. Hu et al prepared the copolymers from DMFD with final molecular weights 6790–11,250 g/mol, that exhibited up to 20% weight loss after 40 days of enzymatic hydrolysis [ 85 ], and Morales-Huerta et al prepared them from cyclic oligo-BF with Mw = 22,000–50,000 g/mol with weight loss of about 55% after 40 days [ 86 ].…”