Catalytic Systems for the Production of Poly(lactic acid)

Byers, Jeffery A.; Biernesser, Ashley B.; Chiaie, Kayla R. Delle; Kaur, Aman; Kehl, Jeffrey A.

doi:10.1007/12_2017_20

Cited by 30 publications

(39 citation statements)

References 186 publications

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“…Commercial high molar mass PLAs are produced by ring‐opening polymerization of lactide, which is the cyclic dimer of lactic acid . Since lactic acid has a chiral carbon, its polymers can have a variety of configurational isomers consisting of enantiomeric l ‐ and d ‐lactic acid units in different sequences and ratios.…”

Section: Introductionmentioning

confidence: 99%

Influence of α′‐/α‐crystal polymorphism on properties of poly(l‐lactic acid)

Lorenzo

Androsch

2018

Polymer International

109

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Poly(l‐lactic acid) (PLLA) is a biodegradable and biocompatible thermoplastic polyester produced from renewable sources, widely used for biomedical devices, in food packaging and in agriculture. It is a semicrystalline polymer, and as such its properties are strongly affected by the developed semicrystalline morphology. As a function of the crystallization temperature, PLLA can form different crystal modifications, namely α′‐crystals below about 120 °C and α‐crystals at higher temperatures. The α′ modification is therefore of special importance as it may be the preferred polymorph developing at processing‐relevant conditions. It is a metastable modification which typically transforms into the more stable α‐crystals on annealing at elevated temperature. The structure, kinetics of formation and thermodynamics of α′‐ and α‐crystals of PLLA are reviewed in this contribution, together with the effect of α′‐/α‐crystal polymorphism on the properties of PLLA. © 2018 Society of Chemical Industry

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Section: Introductionmentioning

confidence: 99%

Influence of α′‐/α‐crystal polymorphism on properties of poly(l‐lactic acid)

Lorenzo

Androsch

2018

Polymer International

109

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“…This broad variation can be achieved via different chain lengths, different topologies, different stereosequences, by copolymerization with various comonomers and blending with another polymer 1–8 . Almost all homo‐ and copolymers of lactic acid are produced by ring‐opening polymerization (ROP) of lactide, and for their technical production (by polymerization in bulk) tin(II) 2‐ethylhexanoate (SnOct 2 ) is the most widely used catalyst 9–11 . The extraordinary usefulness of this catalyst may be attributed to the following properties.…”

Section: Introductionmentioning

confidence: 99%

“…Because many billions of cans have been used for food preserving over a period of 100 years, the toxicity of tin(II) ions has extensively been studied. [9][10][11] Most of these cans were produced from steel, but their interior is plated with tin as anticorrosive coating.…”

Section: Introductionmentioning

confidence: 99%

ROP of L‐lactide and ε‐caprolactone catalyzed by tin(ii) and tin(iv) acetates–switching from COOH terminated linear chains to cycles

Kricheldorf

Weidner

2021

Journal of Polymer Science

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The catalytic potential of tin(II)acetate, tin(IV)acetate, dibutyltin‐bis‐acetate and dioctyl tin‐bis‐acetate was compared based on polymerizations of L‐lactide conducted in bulk at 160 or 130°C. With SnAc2 low‐Lac/Cat ratios (15/1–50/1) were studied and linear chains having one acetate and one carboxyl end group almost free of cyclics were obtained. Higher monomer/catalyst ratios and lower temperatures favored formation of cycles that reached weight average molecular weights (Mw's) between 100,000 and 2,500,000. SnAc4 yielded mixtures of cycles and linear species under all reaction conditions. Dibutyltin‐ and dioctyl tin bis‐acetate yielded cyclic polylactides under most reaction conditions with Mw's in the range of 20,000–80,000. Ring‐opening polymerizations performed with ε‐caprolactone showed similar trends, but the formation of COOH‐terminated linear chains was significantly more favored compared to analogous experiments with lactide. The reactivity of the acetate catalysts decreased in the following order: SnAc2 > SnAc4 > Bu2SnAc2 ~ Oct2SnAc2.

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“…Complexes of hafnium have been predominantly used as Lewis acid catalysts in various organic transformations, such as the polymerization of cyclic esters, and as catalysts for the homo‐ and copolymerization of α‐olefins . Recently, Hf‐MOF compounds have been used as active catalysts for the activation of small molecules .…”

Section: Introductionmentioning

confidence: 99%

Hydroboration of Aldehydes, Ketones, and Carbodiimides Promoted by Mono(imidazolin‐2‐iminato) Hafnium Complexes

et al. 2020

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Imidazolin‐2‐iminato hafnium complexes of the type [(ImRN)Hf(CH2Ph)3] were synthesized (ImtBuN = 1,3‐di‐tert‐butylimidazolin‐2‐iminato); ImDippN = 1,3‐bis(2,6‐diisopropylphenyl)‐imidazolin‐2‐iminato. The complexes were crystallized and structurally characterized. Despite the oxophilicity of the hafnium center, both hafnium complexes were catalytically active in the hydroboration of aldehydes, ketones, and carbodiimides. Herein, we present the influence of different substrates bearing electron‐withdrawing or electron‐donating groups on the catalytic reactions. Based on stoichiometric reaction in each process, plausible mechanistic scenarios are presented.

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Catalytic Systems for the Production of Poly(lactic acid)

Cited by 30 publications

References 186 publications

Influence of α′‐/α‐crystal polymorphism on properties of poly(l‐lactic acid)

Influence of α′‐/α‐crystal polymorphism on properties of poly(l‐lactic acid)

ROP of L‐lactide and ε‐caprolactone catalyzed by tin(ii) and tin(iv) acetates–switching from COOH terminated linear chains to cycles

Hydroboration of Aldehydes, Ketones, and Carbodiimides Promoted by Mono(imidazolin‐2‐iminato) Hafnium Complexes

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