Understanding the phosphoric acid catalysed ring opening polymerisation of β-Butyrolactone and other cyclic esters

Macdonald, Emily K.; Shaver, Michael P.

doi:10.1016/j.eurpolymj.2017.04.005

Cited by 21 publications

(21 citation statements)

References 31 publications

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“…56 Shaver studied the dependence of the acidity of diaryl phosphates on the substitution into the ring. 57 The corresponding Hammett plot, for the acid strengths of diaryl phosphates, taken in extenso from Shaver's paper is shown in Figure 3.…”

Section: Factors Influencing Crop Polymerizability According To Ace A...mentioning

confidence: 99%

“…75 However, it has been shown by the authors from the University of Edinburgh that the reported synthetic methods were not correct, and improved methods were provided. 57 In the paper cited above, 75 it was also stated that mono-and diaryl phosphates not only are catalysts but also act as initiators, and the following picture was presented, showing the alleged structure of the resulting polymers with catalysts as parts of macromolecules, in the form of a mixed anhydride. In Scheme 10, the assumed structure of polyesters formed by CROP is shown according to ref 75. In another paper, on the same subject, it was demonstrated that diaryl phosphates are merely catalysts and are not present in the polymer.…”

Section: Factors Influencing Crop Polymerizability According To Ace A...mentioning

confidence: 99%

“…structures of several protonic acids, used in CROP, was given in the previous sections. 55,57 Triflic acid, belonging to the strongest acids, was used first in CROP a long time ago (1973), namely, in CROP of THF and cyclic acetals (the least basic among cyclic monomers). 86 Most probably TfOH is (or was) used (in ppm concentration) in industrial CROP of 1,3,5-trioxane, leading to the high molar mass thermoplastic polyacetal.…”

Section: Amm Polymerization Of Cyclic Esters Initiated With Protic Co...mentioning

confidence: 99%

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Activated Monomer Mechanism (AMM) in Cationic Ring-Opening Polymerization. The Origin of the AMM and Further Development in Polymerization of Cyclic Esters

Penczek

Pretula

2021

ACS Macro Lett.

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The origin of the activated monomer mechanism (AMM) in cationic ring-opening polymerization (CROP) is described first. Then, conditions leading to the active chain end (ACE) mechanism and AMM are compared, as well as methods allowing to distinguish between these two mechanisms. These methods are based on the “ion trapping” of the active ionic species using highly basic phosphines or by comparing ACE and AMM kinetics of polymerization. The major factors deciding on the actual mechanism include: basicity of the monomers, ring strain, and the presence of the protic additives in the reaction system. These factors are tabulated for major cyclic ethers and cyclic esters. The historically evolved subsequent steps of AMM in the polymerization of cyclic esters are described: from the first experiments with trialkyloxonium salts, precursors of protonic acids, and added alcohols, via HCl as catalyst, and then CF3S(O)2OH (polymerizing lactides) to the most popular derivatives of phosphoric acid, like diphenyl phosphate. Conditions allowing to synthesize poly(ε-caprolactone) (PCL), according to AMM-CROP, with molar mass up to 105 g·mol–1, are described as well as methods to polymerize CL with a protic initiator and acidic catalyst in one molecule. Then various methods enhancing the activity of the polymerizing systems are compared, based predominantly on hydrogen bonding, either to the polymer active end group (usually the hydroxyl group) or to the acid anion. Finally, kinetic equations for ACE and AMM are compared, and it is shown that the majority of the AMM-CROP systems, mostly studied for CL and lactides, proceed as living/controlled polymerizations. Since polymer end groups are hydroxyl groups, then, as it was shown in several papers, any initiator with one or many hydroxyl groups provides macromolecules with the corresponding architecture. The papers on synthetic methods are not discussed in detail.

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Section: Factors Influencing Crop Polymerizability According To Ace A...mentioning

confidence: 99%

Section: Factors Influencing Crop Polymerizability According To Ace A...mentioning

confidence: 99%

Section: Amm Polymerization Of Cyclic Esters Initiated With Protic Co...mentioning

confidence: 99%

See 1 more Smart Citation

Activated Monomer Mechanism (AMM) in Cationic Ring-Opening Polymerization. The Origin of the AMM and Further Development in Polymerization of Cyclic Esters

Penczek

Pretula

2021

ACS Macro Lett.

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“…1,13 Hong and Chen even took a step further and showed that the polymer can be fully recycled back to the starting material. 1 The cationic polymerization of cyclic esters has been reported using a variety of acids, including trifluoromethanesulfonic acid, 14 phosphoric acid, 15 methane/benzene sulfonic acid 16 or HCl•Et 2 O. 17 Smaller cycles such as propiolactone are polymerized with enzymes, 18 Lewis acids 19 or perchloric acid 20 in literature.…”

Section: Introductionmentioning

confidence: 99%

A systematic study of temperature‐dependent cationic photopolymerization of cyclic esters

Mete

Knaack

Liska

2021

Polymer International

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The polymerization of cyclic esters to form polyesters is a thoroughly investigated topic and can be performed via anionic, cationic or metal‐mediated techniques. While there have been attempts to apply light‐induced on‐demand initiation techniques, in most investigations photobase generators are used. In this work the focus lies on photoacid generators, which – contrary to many photobase generators – are easily stored, thermally stable, reactive, less sensitive towards water and oxygen inhibition and commercially available in various forms. However, in most cases the low reactivity of the monomers requires long polymerization times. Therefore, this study provides a basic study of the temperature‐dependent cationic photopolymerization of cyclic esters and shows that polyesters can be formed in less than 5 min of irradiation at elevated temperatures and without solvents, leading to highly crystalline products. In addition, the temperature‐dependent crystallinity, molecular weights and dispersities of the polymers are investigated and presented. © 2021 The Authors. Polymer International published by John Wiley & Sons Ltd on behalf of Society of Industrial Chemistry.

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“…105 Phosphoric and phosphoramidic acids, the weak acidity of which contrasts with strong acids used for electrophilic monomer activated ROP, 13 can act as bifunctional organocatalysts for ROP. [112][113][114][115][116][117] Diphenyl phosphate (21), phosphoramidic (22) and imidodiphosphoric (23) acids were used for the ROP of cyclic esters and carbonates, Figure 1.6. Catalysts 21 and 22 were found to be active towards the ROP of CL, yielding conversion to polymer in 5.5 and 1.5 h, respectively.…”

Section: Non-(thio)urea Lewis Acid/base Catalysis Sulfonamides Phospmentioning

confidence: 99%

Organocatalytic Pathway to the Creation of Polymeric Materials with Some Mechanistic Investigations

Datta¹

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The overarching theme of my research work involves understanding the mechanistic aspects of dually activated hydrogen-bonding catalyst systems and applying that knowledge to synthesize polymers from some of the less explored monomers. This entailed a thorough approach to some of the already hypothesized mechanisms in the polymer community and building on that with additional perspective on catalytic interactions. The other aspect of my research encompassed the application of these H-bond mediated catalysts in controlled ring-opening polymerization (ROP) of sulfur-based lactones. This allowed the growth in monomer scope using these catalysts for the first time. H-bonding catalysis, particularly the ones involving ureas and thioureas, began about a decade or so ago. The tremendous rise in organocatalytic ring-opening polymerization has sparked a wide range of catalysts developments in the past few years. Due to their lower cost, reduced toxicity and greener approach, the field has been booming vii

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Understanding the phosphoric acid catalysed ring opening polymerisation of β-Butyrolactone and other cyclic esters

Cited by 21 publications

References 31 publications

Activated Monomer Mechanism (AMM) in Cationic Ring-Opening Polymerization. The Origin of the AMM and Further Development in Polymerization of Cyclic Esters

Activated Monomer Mechanism (AMM) in Cationic Ring-Opening Polymerization. The Origin of the AMM and Further Development in Polymerization of Cyclic Esters

A systematic study of temperature‐dependent cationic photopolymerization of cyclic esters

Organocatalytic Pathway to the Creation of Polymeric Materials with Some Mechanistic Investigations

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