Anionic polycondensation and equilibrium driven monomer formation of cyclic aliphatic carbonates

Geng, Hua; Olsén, Peter; Franzén, Johan; Odelius, Karin

doi:10.1039/c8ra08219g

Cited by 9 publications

(9 citation statements)

References 59 publications

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“…rac-1-MeTMC was synthesized according to a ring-closing depolymerization procedure. 26 The obtained product was passed through an Isolera 4 (Biotage, Sweden) for flash purification (1:3, v/v, hexane/ethyl acetate), redistilled over CaH 2 , and followed by three freeze−pump−thaw cycles using a Schlenk apparatus right before transferring the monomer into a glovebox (Mbraun MB 150-GI, Germany). Detailed 1 H and 13 C NMR of the monomer is given in the Supporting Information (Figures S1 and S2).…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Phosphazene-Catalyzed Regioselective Ring-Opening Polymerization of rac-1-Methyl Trimethylene Carbonate: Colder and Less is Better

2019

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The regioselective organocatalytic ring-opening polymerization (ROP) of a 6-membered cyclic carbonate, rac-1-methyl trimethylene carbonate, was studied using phosphazene base (t-BuP2) as the principle catalyst. The influence on the reaction kinetics caused by the reaction temperature (−74–60 °C), catalyst loading (0.5–2.5%), and reaction solvent (toluene and tetrahydrofuran) was systematically tuned and followed by 1H NMR. All studied reactions reached close to or above 90% monomer conversion in 3 h, and all exhibited typical equilibrium polymerization behavior that is inherent to 6-membered cyclic carbonates. Good control over the molecular weight and distribution of the polycarbonate product was obtained in most studied conditions, with M n ranging from ∼4k to ∼20k and Đ < 1.2. The regioregularity (X reg) of the resulting polycarbonate was thoroughly studied using various NMR techniques, with the highest X reg obtained being 0.90. The major influence from the reaction conditions on both the ROP kinetics and X reg are as follows: higher reaction temperature resulted in a decrease of both; higher catalyst loading resulted in a faster ROP reaction but a slight decrease in X reg; and toluene being a better solvent resulted in both faster reaction and higher X reg. Throughout this study, we have demonstrated the possibility to synthesize regioregular aliphatic polycarbonate using an organic base as the ROP catalyst, contrary to the existing studies on similar systems where only metal–base catalysts were in focus and our systems showed similar high X reg of the product.

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Section: ■ Experimental Sectionmentioning

confidence: 99%

Phosphazene-Catalyzed Regioselective Ring-Opening Polymerization of rac-1-Methyl Trimethylene Carbonate: Colder and Less is Better

2019

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“…We previously developed a series of six-membered cyclic carbonates through RCE of in situ -generated polycarbonate derived from 1,3-propanediol derivatives and ethyl carbonate. − Unfortunately, the same methodology was not applicable to the formation of MCs. Here, we address this issue by developing a one-pot, direct, and scalable methodology for a library of inexpensive MCs through selective transesterification ring-closure depolymerization (Scheme , Figure ).…”

Section: Introductionmentioning

confidence: 99%

Simple Approach to Macrocyclic Carbonates with Fast Polymerization Rates and Their Polymer-to-Monomer Regeneration

et al. 2022

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Designing polymeric materials for closed-loop material streams is the key to achieving a circular society. Here, a library of macrocyclic carbonates (MCs) was designed by a facile and direct one-pot, two-step synthesis approach without the use of a solvent at a 10 g scale. We demonstrate that anionic polymerization with tert-butoxide enables the ultrafast ring-opening polymerization (ROP) of MCs with high conversion (>97%) within seconds (3–10 s) at ambient temperature. The polymerization rate depends on the odd or even number of methylene groups between the carbonate linkages in the MCs, and not the overall ring size, yielding an “odd–even” effect. This polymerization rate is related to the difference in molecular conformation of the MCs, as determined by X-ray crystallography. The polymers (polypenta-, hexa-, heptamethylene carbonate) were subsequently regenerated back to their original MCs at a high selectivity (95–99 mol %) and good yields (70–85%), hence taking a step toward closing the loop on these long alkyl chain polycarbonates.

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“…We followed a greener protocol established by Olsén and co-workers , that involves the polymerization/oligomerization of a diol in the presence of diethyl carbonate using sodium hydride as a catalyst, followed by ring-closing depolymerization at high temperatures under reduced pressures (Scheme ). According to this method, the product is distilled and collected from the reaction mixture as it is formed, facilitating purification. Hua and co-workers recently used this method to prepare the racemic-1,3-butylene carbonate monomer rac -BC .…”

Section: Results and Discussionmentioning

confidence: 99%

Regioregular Polymers from Biobased (R)-1,3-Butylene Carbonate

et al. 2021

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We present (R)-1,3-butylene carbonate ( R-BC) as a biorenewable monomer for the preparation of semicrystalline aliphatic polycarbonates. This conversion is achieved by using enantiomerically pure, biobased (R)-(−)-1,3-butanediol (bio-BG) as a renewable feedstock. Ring-opening polymerization from select catalysts at low temperatures can yield regioregular poly((R)-1,3-butylene carbonate) ( R-PBC) with semicrystalline properties (X reg = > 0.99; T m = 72 °C). Along with the R-enantiomeric polymer, the alternate stereochemical polymers (using S- and racemic BC) were investigated. Our analysis shows that the highest level of crystallinity is achieved with regioregular, biobased R -PBC compared to the petrol-based S- and racemic congeners. This work shows the potential of stereochemically pure bio-BG as a starting material for semicrystalline, aliphatic carbonates when high regioregularity is achieved in the polymer microstructure. The synthesis and thermal characterization of regioregular butylene carbonate polymers are described in detail.

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Anionic polycondensation and equilibrium driven monomer formation of cyclic aliphatic carbonates

Abstract: One-pot two-step phosgene-free method to make functionalized 6-membered cyclic-carbonates and aliphatic polycarbonates in large quantity.

Cited by 9 publications

References 59 publications

Phosphazene-Catalyzed Regioselective Ring-Opening Polymerization of rac-1-Methyl Trimethylene Carbonate: Colder and Less is Better

Phosphazene-Catalyzed Regioselective Ring-Opening Polymerization of rac-1-Methyl Trimethylene Carbonate: Colder and Less is Better

Simple Approach to Macrocyclic Carbonates with Fast Polymerization Rates and Their Polymer-to-Monomer Regeneration

Regioregular Polymers from Biobased (R)-1,3-Butylene Carbonate

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