One-step synthesis of stereo-pure l,l lactide from l-lactic acid

Ghadamyari, Marzieh; Chaemchuen, Somboon; Zhou, Kui; Dusselier, Michiel; Sels, Bert F.; Mousavi, Bibimaryam; Verpoort, Francis

doi:10.1016/j.catcom.2018.06.003

Cited by 27 publications

(20 citation statements)

References 21 publications

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“…High‐molecular‐weight PLA is preferentially prepared from the cyclic dimer of lactic acid, lactide (LA), through ring‐opening polymerization (ROP) . Current PLA research seeks to reduce energy/material input of LA monomer synthesis, demonstrate and elucidate stereoselective initiation and prepare robust initiators to compete with Sn(Oct) 2 under industrial conditions …”

Section: Methodsmentioning

confidence: 99%

Zinc Complexes for PLA Formation and Chemical Recycling: Towards a Circular Economy

et al. 2019

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As eries of Zn II complexes, based on propylenediamineS chiff bases, have been prepared and fully characterized. X-ray crystallography and NMR spectroscopy identified significant differences in the solid and solution state for the Zn II species. All complexes have been applied to the ring-opening polymerization of l-lactidew ith emphasis on industrial conditions. High conversion and good molecularw eight control were generally achievablef or Zn(A-D) 2 ,a nd high-molecular-weight poly(lactic acid) (PLA) was prepared in 1min at a1 0000:1:33 [lactide]/ [Zn]/[BnOH] loading. The more active Zn II catalysts were also appliedt oP LA degradation to alkyl lactateu nder mild conditions. Zn(A-B) 2 demonstrated high activity and selectivity in this process with PLA being consumed within 1h at 50 8C. Zn(C-D) 2 were shown to be less active, and these observations can be relatedt ot he catalysts' structure and the degradation mechanism. Initialr esultsf or the degradation of poly(ethylene terephthalate) and mixed feeds are also presented, highlighting the broader applicability of the systems presented.Owing to the inevitable depletion of fossil fuel resources, and inherentc arbon emissions, alternatives to petrochemical plastics are desperately needed. [1] Poly(lactic acid) (PLA) is apotential replacement for fossil-fuel-derived plastics used for packaging applications. [2,3] PLA has the added advantageo f being biocompatible and therefore suitable for biomedical applications. [4,5] Because it is derived from annually harvested crops, PLA is biorenewable and has promising green credentials in terms of CO 2 emissions and life-cycle assessment. [6,7] High-molecular-weight PLA is preferentially prepared from the cyclic dimer of lactic acid, lactide (LA), through ring-opening polymerization (ROP). [8] CurrentP LA research seeks to reduce energy/material input of LA monomer synthesis, [9][10][11][12] demonstrate ande lucidate stereoselective initiation [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] and prepare robust initiators to compete with Sn(Oct) 2 under industrial conditions. [30][31][32][33][34] Plastic waste andp ollution are af urther 21 st century challenge forboth academia and industry.Although PLA is biodegradable under high-temperature industrial conditions, it will not readily degrade in the natural environmenta nd therefore will contribute to the millions of tonnes of waste in landfill and in oceans. [35][36][37] End-of-life plastic waste managementi s key to tackling this issue, andi ti si mperative this is addressed for all aspiring materials such as PLA. For PLA, chemical recycling is ap articularly attractive route because it can produce value-added products such as alkyl lactates, lactic acid and acrylic acid. [38,39] These can be usefuli nt heir own right or used to reform LA, and therefore PLA, to facilitate ac ircular-economy approach. Lactic acid, for example, is regarded as ap latform chemical, and alkyl lactates are considered green solvents. [40][41][42][43][44] The conversion of PLA ...

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Section: Methodsmentioning

confidence: 99%

Zinc Complexes for PLA Formation and Chemical Recycling: Towards a Circular Economy

et al. 2019

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“…[63] Thus, research has been devoted to reducing production costs by targeting the production of lactide directly in one‐step processes, exploiting the use of shape‐selective catalysis and gas‐phase reactions. [ 64 , 65 , 66 , 67 , 68 , 69 , 70 ] However, it is clear PLA will play a prominent role in a future plastics economy as the uptake of bio‐based products increases. [5] Indeed, the production and use of PLA has the potential to reduce GHG emissions and non‐renewable energy use by 40 and 25 %, respectively, compared to traditional petroleum‐based plastics, including PE and PET.…”

Section: Chemical Recycling Of Poly(lactic Acid)mentioning

confidence: 99%

The Chemical Recycling of Polyesters for a Circular Plastics Economy: Challenges and Emerging Opportunities

2021

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Whilst plastics have played an instrumental role in human development, growing environmental concerns have led to increasing public scrutiny and demands for outright bans. This has stimulated considerable research into renewable alternatives, and more recently, the development of alternative waste management strategies. Herein, the aim was to highlight recent developments in the catalytic chemical recycling of two commercial polyesters, namely poly(lactic acid) (PLA) and poly (ethylene terephthalate) (PET). The concept of chemical recy-cling is first introduced, and associated opportunities/challenges are discussed within the context of the governing depolymerisation thermodynamics. Chemical recycling methods for PLA and PET are then discussed, with a particular focus on upcycling and the use of metal-based catalysts. Finally, the attention shifts to the emergence of new materials with the potential to modernise the plastics economy. Emerging opportunities and challenges are discussed within the context of industrial feasibility.

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“…[23][24][25][26][27] Both degradation products can also be transformed to lactide, which is the first step towards polymer synthesis. [28][29][30] For some polymers, chemical recycling can be achieved thermally by pyrolysis, depolymerising the material directly back to monomers. 31 Pyrolysis of PLA can access lactide directly, however this requires high-temperatures and can increase the amount of by-products formed.…”

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confidence: 99%