A non-phosgene process to homopolycarbonate and copolycarbonates of isosorbide using dimethyl carbonate: Synthesis, characterization, and properties

Green Synthesis of UV-Reactive Polycarbonates from Levoglucosenone and 5-Hydroxymethyl Furfural

This study focuses on the synthesis of fully renewable polycarbonates (PCs) starting from cellulose-based platform molecules levoglucosenone (LGO) and 2,5-bis(hydroxymethyl)furan (BHMF). These unique bio-based PCs are obtained through the reaction of a citronellol-containing triol (Triol-citro) derived from LGO, with a dimethyl carbonate derivative of BHMF (BHMF-DC). Solvent-free polymerizations are targeted to minimize waste generation and promote an eco-friendly approach with a favorable environmental factor (E-factor). The choice of metal catalyst during polymerization significantly influences the polymer properties, resulting in high molecular weight (up to 755 kDa) when Na2 CO3 is employed as an inexpensive catalyst. Characterization using nuclear magnetic resonance confirms the successful incorporation of the furan ring and the retention of the terminal double bond of the citronellol pendant chain. Furthermore, under UV irradiation, the presence of both citronellol and furanic moieties induces singular structural changes, triggering the formation of three distinct structures within the polymer network, a phenomenon herein occurs for the first time in this type of polymer. These findings pave the way to new functional materials prepared from renewable monomers with tunable properties.

En Route to CO2-Based (a)Cyclic Carbonates and Polycarbonates from Alcohols Substrates by Direct and Indirect Approaches

This review is dedicated to the state-of-the art routes used for the synthesis of CO2-based (a)cyclic carbonates and polycarbonates from alcohol substrates, with an emphasis on their respective main advantages and limitations. The first section reviews the synthesis of organic carbonates such as dialkyl carbonates or cyclic carbonates from the carbonation of alcohols. Many different synthetic strategies have been reported (dehydrative condensation, the alkylation route, the “leaving group” strategy, the carbodiimide route, the protected alcohols route, etc.) with various substrates (mono-alcohols, diols, allyl alcohols, halohydrins, propargylic alcohols, etc.). The second section reviews the formation of polycarbonates via the direct copolymerization of CO2 with diols, as well as the ring-opening polymerization route. Finally, polycondensation processes involving CO2-based dimethyl and diphenyl carbonates with aliphatic and aromatic diols are described.

Sustainable Hyperbranched Functional Materials via Green Polymerization of Readily Accessible Levoglucosenone-Derived Monomers

The homopolymerization in basic conditions of the recently reported bis(γ-lactone), 2H-HBO-HBO, is herein described for the first time. The solvent-free polymerization of this pentafunctional levoglucosenone (LGO) derivative affords fully renewable poly(vinyl-ether lactone) copolymers with a highly hyperbranched structure. This investigation stems from the polycondensation trials between 2H-HBO-HBO and di(methyl carbonate) isosorbide (DCI) that fails to give the anticipated polycarbonates. Such unexpected behavior is ascribed to the higher reactivity of the 2H-HBO-HBO hydroxy groups toward its α,β-conjugated endocyclic C═C, rather than the DCI methylcarbonate moieties. The different mechanistic scenarios involved in 2H-HBO-HBO homopolymerization are addressed and a possible structure of poly(2H-HBO-HBO) is suggested. Furthermore, the readily accessible (S)-γ-hydroxymethyl-α,β-butenolide (HBO) is also polymerized for the first time at a relatively large scale, without any prior modification, resulting in a new hyperbranched polymer with an environmental factor (E factor) ≈0. These new HBO-based polymers have a great potential for industrial-scale production due to their interesting properties and easy preparation via a low-cost, green, and efficient process.

Balancing the transesterification reactivity of isosorbide with diphenyl carbonate: preferential activation of exo-OH

Exo-OH on ISB has long been asserted as a highly reactive moiety compared with endo-OH. Herein, we report that the nucleophilic attack surmounts steric hindrance in rendering endo-OH more reactive than exo-OH in case of transesterification with DPC.

Copolycarbonates Based on a Bicyclic Diol Derived from Citric Acid and Flexible 1,4-Cyclohexanedimethanol: From Synthesis to Properties

Octahydro-2,5-pentalenediol (OPD), is a compelling citric acid-based bicyclic diol with excellent rigidity and thermal stability. Herein, a series of copolycarbonates (co-PCs) were synthesized, starting from OPD, 1,4-cyclohexanedimethanol (CHDM), and diphenyl carbonate (DPC). All polycarbonates are amorphous with glass transition temperatures increased when increasing the content in OPD units. Dynamic mechanical analysis (DMA) revealed the sub T_g β-relaxations at low temperatures originating from the CHDM conformational transition, indicative of the possibility of impact-resistance. Morphological analysis of the fracture surfaces revealed the toughening mechanism under tensile was shear yielding of the matrix triggered by internal cavitation. The incorporation of OPD steadily increased the Young's modulus, from 482 to 757 MPa, with the OPD fraction increased from 0 to 30 mol %. As the OPD content further increased, a "ductile-to-brittle" transition occurred due to the low number-average molecular weight (M_n) and the low entangled strand density (high entanglement molecular weight).

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

Green synthesis of high-molecular-weight isosorbide-based polycarbonate (PIC) with excellent properties is a tremendous challenge and is profoundly influenced by the precursor. Herein, an ecofriendly catalyst was employed to obtain the more reactive PIC precursor dicarboxymethyl isosorbide (DC) with 99.0 % selectivity through the transesterification reaction of isosorbide with dimethyl carbonate. This is the indispensable stage of a one-pot green synthesis of PIC, playing a critical role in giving an insight into the polymerization mechanism of polymer synthesis through the melt transesterification reaction. To this end, a series of 4-substituted phenolate ionic liquids (ILs) were developed as a new type of high-efficiency catalyst for this reaction. These homogeneous ILs exhibited outstanding catalytic performances. The DC selectivity increased gradually with decreasing IL basicity; among the ILs studied, trihexyl(tetradecyl)phosphonium 4-iodophenolate ([P₆₆₆₁₄ ][4-I-Phen]) showed the highest catalytic activity. Additionally, according to the experimental results and DFT calculations, a plausible nucleophilic activation mechanism was proposed, which confirmed that the reaction is activated through the formation of H-bonds and electrostatic interactions with the IL catalyst. This strategy of tunable basicity and structure of anions in ILs affords an opportunity to develop other ILs for the transesterification reaction, thereby conveniently providing a variety of polymers through a green synthetic pathway.

A facile method to synthesize bio-based and biodegradable copolymers from furandicarboxylic acid and isosorbide with high molecular weights and excellent thermal and mechanical properties

Biobased, biodegradable copolymers containing isosorbide and 2,5-furandicarboxylic acid with high performance are successfully synthesized through a non-solvent and economical pathway.

A synthetic strategy toward isosorbide polycarbonate with a high molecular weight: the effect of intermolecular hydrogen bonding between isosorbide and metal chlorides

Isosorbide polycarbonate (ISB-PC) was prepared by melt transesterification and polycondensation reaction by employing ISB and diphenyl carbonate (DPC) as monomers.

Advances in the use of CO2 as a renewable feedstock for the synthesis of polymers

Carbon dioxide offers an accessible, cheap and renewable carbon feedstock for synthesis. Current interest in the area of carbon dioxide valorisation aims at new, emerging technologies that are able to provide new opportunities to turn a waste into value. Polymers are among the most widely produced chemicals in the world greatly affecting the quality of life. However, there are growing concerns about the lack of reuse of the majority of the consumer plastics and their after-life disposal resulting in an increasing demand for sustainable alternatives. New monomers and polymers that can address these issues are therefore warranted, and merging polymer synthesis with the recycling of carbon dioxide offers a tangible route to transition towards a circular economy. Here, an overview of the most relevant and recent approaches to CO2-based monomers and polymers are highlighted with particular emphasis on the transformation routes used and their involved manifolds.

Ring-opening polymerization of trimethylene carbonate to poly(trimethylene carbonate) diol over a heterogeneous high-temperature calcined CeO2 catalyst

CeO₂ calcined at 1273 K was an effective reusable heterogeneous catalyst for the synthesis of poly(trimethylene carbonate) diol by ring-opening polymerization of trimethylene carbonate under neat conditions without any additives.

Environmentally-Friendly Synthesis of Carbonate-Type Macrodiols and Preparation of Transparent Self-Healable Thermoplastic Polyurethanes

Carbonate-type macrodiols synthesized by base-catalyzed polycondensation of co-diols and dimethyl carbonate as an environmentally-friendly route were subsequently utilized for the preparation of transparent and self-healable thermoplastic polyurethanes (TPUs) containing a carbonate-type soft segment. Three types of macrodiols, obtained from mono, dual and triple diol-monomers for target molecular weights of 1 and 1.5 kg mol-1, were analyzed by ¹H NMR integration and the OH titration value. Colorless transparent macrodiols in a liquid state at a room temperature of 20 °C were obtained, except the macrodiol from mono 1,6-hexanediol. Before TPU synthesis, macrodiols require pH neutralization to prevent gelation. TPUs synthesized by a solution pre-polymer method with 4,4'-methylene(bisphenyl isocyanate) and 1,4-butanediol as a chain extender exhibited moderate molecular weights, good transparencies and robust mechanical properties. Especially, the incorporation of 3-methyl-1,5-pentanediol within carbonate-type macrodiols enhanced the transparency of the resultant TPUs by decreasing the degree of microphase separation evidenced by ATR-FTIR and DSC. Interestingly, packing density of hard segments and the degree of microphase separation determined the self-healing efficiency of TPUs, which showed good performances in the case of sourced macrodiols from triple diol-monomers.

Bio-Based Poly(Ether Imide)s from Isohexide-Derived Isomeric Dianhydrides

In this work, four isohexide-derived isomeric dianhydrides were synthesized through a four-step procedure using isohexide and chloro-N-phenylphthalimides as the starting materials. The one-step solution polymerization of these dianhydrides with petroleum- or bio-based diamines enabled the synthesis of poly(ether imide)s (PEIs), which had viscosities of 0.41 to 2.40 dL∙g-1. The isohexide-derived PEIs were characterized based upon their solubility and their thermal, mechanical, and optical properties. The results showed that most of the isohexide-derived PEIs possessed comparable glass transition temperatures (Tg), tensile strengths, and moduli to petroleum-based PEIs. However, the thermo-oxidative stability of the PEIs was found to be lower than that of the common petroleum-based PEIs. Moreover, the PEIs displayed good optical activity, which originated from their unique chiral isohexide moieties. The isomeric effects of dianhydride monomers on the properties of the resulting PEIs were comparatively studied. The results suggested that the corresponding 4,4'-linked PEIs possessed lower Tg, higher mechanical properties, and higher specific rotations compared to 3,3'-linked polymers. Meanwhile, the polyimides with isomannide residue displayed higher Tg and more specific rotations than the corresponding polymers with isosorbide residue. These results contributed to more restricted rotations of phthalimide segments in 3,3'-linked or isomannide containing polyimides.

Structural Foams of Biobased Isosorbide-Containing Copolycarbonate

Isosorbide-containing copolycarbonate (Bio-PC) is a partly biobased alternative to conventional bisphenol A (BPA) based polycarbonate (PC). Conventional PC is widely used in polymer processing technologies including thermoplastic foaming such as foam injection molding. At present, no detailed data is available concerning the foam injection molding behavior and foam properties of Bio-PC. This contribution provides first results on injection-molded foams based on isosorbide-containing PC. The structural foams were produced by using an endothermic chemical blowing agent (CBA) masterbatch and the low pressure foam injection molding method. The influence of weight reduction and blowing agent concentration on general foam properties such as density, morphology, and mechanical properties was studied. The test specimens consist of a foam core in the center and compact symmetrical shell layers on the sides. The thickness of the foam core increases with increasing weight reduction irrespective of the CBA concentration. The specific (mechanical) bending properties are significantly improved and the specific tensile properties can almost be maintained while reducing the density of the injection-molded parts.

Polymers from sugars and CO2: ring-opening polymerisation and copolymerisation of cyclic carbonates derived from 2-deoxy-d-ribose

We report the preparation of two anomeric cyclic carbonate monomers from CO₂ and natural sugar 2-deoxy-d-ribose, their ring-opening polymerisation and copolymerisation with trimethylene carbonate to produce aliphatic polycarbonates with tunable properties.

A novel one-pot process for the preparation of linear and hyperbranched polycarbonates of various diols and triols using dimethyl carbonate

A novel one-pot method for preparation of high molecular-weight linear and hyperbranched polycarbonates from diols and triols with dimethyl carbonate.

Isosorbide and dimethyl carbonate: a green match

In this review the reactivity of the bio-based platform compounds D-sorbitol and isosorbide with green reagents and solvent dimethyl carbonate (DMC) is reported. Dehydration of D-sorbitol via DMC in the presence of catalytic amounts of base is an efficient and viable process for the preparation of the industrially relevant anhydro sugar isosorbide. This procedure is "chlorine-free", one-pot, environmental friendly and high yielding. The reactivity of isosorbide with DMC is equally interesting as it can lead to the formation of dicarboxymethyl isosorbide, a potential monomer for isosorbide-based polycarbonate, and dimethyl isosorbide, a high boiling green solvent. The peculiar reactivity of isosorbide and the non-toxic properties of DMC represent indeed a green match leading to several industrial appealing potential applications.

Renewability is not Enough: Recent Advances in the Sustainable Synthesis of Biomass-Derived Monomers and Polymers

Taking advantage of the structural diversity of different biomass resources, recent efforts were directed towards the synthesis of renewable monomers and polymers, either for the substitution of petroleum-based resources or for the design of novel polymers. Not only the use of biomass, but also the development of sustainable chemical approaches is a crucial aspect for the production of sustainable materials. This review discusses the recent examples of chemical modifications and polymerizations of abundant biomass resources with a clear focus on the sustainability of the described processes. Topics such as synthetic methodology, catalysis, and development of new solvent systems or greener alternative reagents are addressed. The chemistry of vegetable oil derivatives, terpenes, lignin, carbohydrates, and sugar-based platform chemicals was selected to highlight the trends in the active field of a sustainable use of renewable resources.