Tailoring Molecular Weight of Bioderived Polycarbonates via Bifunctional Ionic Liquids Catalysts under Metal-Free Conditions

Abstract

Synthesis of bioderived high-molecular-weight polycarbonates over metal-free catalysts is of great importance but also challenging. In this work, a series of 1-butyl-3-methylimidazolium (Bmim) ionic liquids (ILs) were prepared as catalysts for a melt polycondensation reaction of isosorbide and diphenyl carbonate. By modifying the structures of ILs’ anions, the number-average molecular weight (M n) of poly­(isosorbide carbonate) (PIC) was effectively tailored. In the presence of a trace amount (0.05 mol % based on isosorbide) of bifunctional [Bmim]­[CH3CHOHCOO], the synthesized PIC possessed high M n of 61,700 g/mol and a glass transition temperature of 174 °C, both the highest so far to the best of our knowledge. Besides, it was found that the anions with stronger electronegativity and hydrogen bond formation ability were more efficient for the formation of PIC with higher M n. To modify the flexibility of PIC, poly­(aliphatic diol-co-isosorbide carbonate)­s with M n ranging from 34,000 to 75,700 g/mol were also formulated by incorporating with various aliphatic diols. Additionally, based on the experimental results and nuclear magnetic resonance spectroscopy, a possible mechanism of cooperative nucleophilic–electrophilic activation through hydrogen bond formation and electrostatic interactions by the ILs catalyst was proposed.

Transesterification of Isosorbide with Dimethyl Carbonate Catalyzed by Task‐Specific Ionic Liquids

“…Upon introduction of the IL, the H signals of the −OH groups in isosorbide at 5.11 and 4.72 ppm were no longer displayed (Figure S2 in the Supporting Information), implying that the H atoms of the −OH groups were activated by forming a H‐bond with the O atom of [4‐H‐Phen] − . This is similar to results described in the literature . Moreover, DMC was also activated by the IL, which could be deduced from the 1 H NMR spectroscopy of the mixture of DMC and [P 66614 ][4‐H‐Phen].…”

“…According to the experimental results, simulation results, and previous reports, a plausible nucleophilic activation mechanism was proposed (Scheme ). The oxygen atom of [4‐R‐Phen] − (R=H, F, Cl, Br, or I) was anticipated to facilitate the nucleophilic activation of isosorbide through a hydrogen bond, similarly to that mentioned in other literature . This deduction was verified by the 1 H NMR chemical shift of the mixture of isosorbide and [P 66614 ][4‐H‐Phen].…”

A Brønsted Acidic Ionic Liquid as an Efficient and Selective Catalyst System for Bioderived High Molecular Weight Poly(ethylene 2,5‐furandicarboxylate)

“…Zhao et al [12] investigated the esterification of aliphatic acids with alcohols by using as eries of Brønsted acidic ILs as catalysts (0.5 mol %based on the aliphatic acids). Ma et al [14] synthesized high-molecular-weight bioderived polycarbonates by using at race amount of ab ifunctional 1-butyl-3-methylimidazolium lactate[ C 4 MIM][CH 3 CHOHCOO] (0.05 mol %b ased on isosorbide). Naik and co-workers [13] proposed the efficient use of 1-n-butyl-3-methylimidazolium-2-carboxylate (BMIM-2-CO 2 )a sacatalyst precursor (1 mol %b ased on diols) in the synthesis of aliphatic polycarbonates by transesterification of dimethyl carbonate and diols.…”

Renewable Isohexide‐Based, Hydrolytically Degradable Poly(silyl ether)s with High Thermal Stability

“…[8] These bifunctional isohexides are chiral and nontoxic, [9] andt he unique aliphatic bicyclic structure with two fused tetrahydrofuran rings confers ah igh strength and rigidity to the molecule. [12] Hence, aw ide range of thermally stable polyesters, [13] polyamides, [14] poly(ester amide)s, [15] poly-(ether imide)s, [16] polymethacrylates, [17] polyurethanes, [18] polycarbonates, [19] and poly(isosorbide fatty alkylates) [20] have been synthesized through either chain or step-growth polymerization. [11] Interestingly,avariety of reactive functionalities such as amine, azide, isocyanate, carboxylic acid, ande ster groups can be installed to replace or extend the originalh ydroxy groups for new starting materials, which further broadens the scope of accessible polymers.…”

“…[11] Interestingly,avariety of reactive functionalities such as amine, azide, isocyanate, carboxylic acid, ande ster groups can be installed to replace or extend the originalh ydroxy groups for new starting materials, which further broadens the scope of accessible polymers. [12] Hence, aw ide range of thermally stable polyesters, [13] polyamides, [14] poly(ester amide)s, [15] poly-(ether imide)s, [16] polymethacrylates, [17] polyurethanes, [18] polycarbonates, [19] and poly(isosorbide fatty alkylates) [20] have been synthesized through either chain or step-growth polymerization. Notably, poly(estera mide)s derived from isohexides are degradable and can be used in biological applications.…”