Biobased and Compostable Multiblock Copolymer of Poly(l-lactic acid) Containing 2,5-Furandicarboxylic Acid for Sustainable Food Packaging: The Role of Parent Homopolymers in the Composting Kinetics and Mechanism

Abstract

In the last years, the exponential growth in the demand of petroleum-based plastic materials, besides the extreme exploitation of nonrenewable resources, lead to the mismanagement of their disposal and to serious ecological issues related to their dispersion in the environment. Among the possible practical solutions, the design of biobased and biodegradable polymers represents one of the most innovative challenges. In such a context, the eco-design of an aromatic–aliphatic multiblock copolymer based on poly(lactic acid) and containing 2,5-furandicarboxylic acid was carried out with the aim of improving the properties of poly(l-lactic acid) for sustainable packaging applications. The synthetic method followed a novel top–down approach, starting from industrial high-molecular-weight poly(l-lactic acid) (PLLA), which was reacted with 1,5-pentanediol to get hydroxyl-terminated PLLA and then chain-extended with hydroxyl-terminated poly(pentamethylene furanoate) (PPeF-OH). The final copolymer, called P(LLA50PeF50)-CE, was subjected to molecular, structural, and thermal characterization. Tensile and gas permeability tests were also carried out. According to the results obtained, PLLA thermal stability was improved, being the range of processing temperatures widened, and its stiffness and brittleness were decreased, making the new material suitable for the realization of films for flexible packaging. The oxygen permeability of PLLA was decreased by 40% and a similar improvement was measured also for carbon dioxide. P(LLA50PeF50)-CE was found to be completely biodegraded within 60 days of composting treatment. In terms of mechanism, the blocks of PPeF and PLLA were demonstrated to undergo surface erosion and bulk hydrolysis, respectively. In terms of kinetics, PPeF blocks degraded slower than PLLA ones.

On the Selective Enzymatic Recycling of Poly(pentamethylene 2,5-furanoate)/Poly(lactic acid) Blends and Multiblock Copolymers

“…Various synthetic polyesters based on the chemical 28 or physical 25 combination of poly(lactic acid) (PLA) and poly(1,5-pentamethylene 2,5-furanoate) (PPeF) were prepared and processed in the form of thin films (≈150 μm). The covalent formulation was a 50 wt % block copolymer of PLA (kindly provided by CORBION) and PPeF connected with a diamine chain extender (see the SI, Scheme S1 ) that from now on will be labeled as P(LA50PeF50).…”

“…On the other hand, PPeF specifically represents an interesting candidate for PLA-based blends and copolymers, and promising properties for packaging applications have been demonstrated. The combination with PPeF overcomes intrinsic PLA brittleness and allows the improvement of its gas barrier properties, , meanwhile not affecting the transparency of the cast films . More in detail, both physical and chemical blending of PLA and PPeF leads to an improvement of the mechanical response in terms of flexibility without compromising the O 2 and CO 2 barrier properties that keep better than polyolefins, , making PLA/PPeF materials suitable for flexible food packaging applications.…”

“…The combination with PPeF overcomes intrinsic PLA brittleness and allows the improvement of its gas barrier properties, , meanwhile not affecting the transparency of the cast films . More in detail, both physical and chemical blending of PLA and PPeF leads to an improvement of the mechanical response in terms of flexibility without compromising the O 2 and CO 2 barrier properties that keep better than polyolefins, , making PLA/PPeF materials suitable for flexible food packaging applications. In this work, for the first time, the potential of enzymatic depolymerization of various PLA/PPeF materials (physical blends and block copolymer) has been investigated, which could open new recycling possibilities for the recovery of valuable building blocks.…”

Tricyclic Diester and 2,5-Furandicarboxylic Acid for the Synthesis of Biobased Hydrolysis Copolyesters with High Glass Transition Temperatures

“…As for the modification of PEF, a series of rigid diols or diacids, such as CHDM, 2,4-FDCA, PTA, and CHDA, were incorporated within the backbone of PEF via the copolymerization, as summarized in Figure . − Mostly, with the increase of content of the second rigid comonomer, the T g of copolyesters presented a decreasing tendency in different degrees compared to PEF. It is exceptional that when PEF was copolymerized with 2,2,4,4-tetramethyl-1,3-cyclobutanediol (CBDO), the increased T g was observed up to 94.3 °C of the copolyesters with 23 mol % CBDO content.…”

Poly(lactic acid) stereocomplex microspheres as thermally tolerant optical resonators

“…1–4 Due to its biodegradable, biocompatible, and nontoxic properties, PLA is widely used in biomedical applications, 5–7 drug transportation, 8 textile, 9 and packaging. 10,11 PLA has three types of stereoisomers: poly( l -lactide acid) (PLLA), poly( d -lactide acid) (PDLA), and their atactic polymer, poly( dl -lactic acid) (PDLLA). 12 The homopolymers of PLLA and PDLA form semicrystalline aggregates with a melting temperature of around 170 °C, while the atactic PDLLA copolymer forms an amorphous aggregate with a lower melting temperature.…”