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The biorenewable carbohydrate-derived rigid building block of isosorbide (ISB) has demonstrated potential in high-performance polymer materials; however, a controllable eco-friendly preparation technology is not yet available. For this purpose, a sustainable strategy to synthesize ISB-based polycarbonate (PIC) has been established by adopting the CO2-based compound dimethyl carbonate (DMC) as a monomer and ionic liquids (ILs) as metal-free catalysts. The molecular weight of PICs can be readily controlled by varying the cation structure of IL catalysts. Control experiments, density functional theory (DFT) calculations, and Kamlet–Taft solvent parameters indicated that the H-bond donor/acceptor (HBD/HBA) ability of IL catalysts played a dominant role in regulating catalytic activity. PIC molecular weight can be modulated by modifying the inherent difference in reactivity of endo-OH and exo-OH in ISB, wherein the chain length or substituent group of cations can regulate the HBD/HBA ability of IL catalysts and anions can specifically activate the carbonyl carbon of DMC. The experimental results revealed that a task-specific [Pmim][OAc] catalyst exhibited the highest catalytic activity, which is attributed to its significant role in considerably lowering the disparity in reactivity between endo-OH and exo-OH. For this DMC route, the [Pmim][OAc] catalyst offered a PIC with the highest molecular weight of 57 200 g mol−1 reported to date. Furthermore, a well-supported polymerization mechanism was proposed, in which [Rmim][OAc]'s anion–cation synergistically catalyzed ISB and DMC to prepare PIC. Our findings offer a clear pathway for designing efficient metal-free catalysts to enable the sustainable synthesis of high molecular weight PICs, thus expediting the industrialization of the DMC route. [ABSTRACT FROM AUTHOR]

Core–shell polyionic liquids were successfully constructed to reduce the amount of bulk ionic liquids and realize heterogeneous catalysis in the reaction of CO2 conversion into carbonate. The core–shell polyionic liquid structure is formed by one-step surface polymerization with cheap and readily available SiO2 as the carrier. By optimizing the ratio of ionic liquid monomer to SiO2, PIL@SiO2(1:1.5) of high activity and low ionic liquid dosage was successfully obtained, and only 40% of bulk ionic liquid dosage was used to achieve high activity of quasi-homogeneous phase (PO conversion 95.5%). Combined with the characterization and mechanism study, it was found that at an appropriate ratio (1:1.5), good mesoporous structure and a certain extent dispersion of polyionic liquid can make the active site better dispersed to facilitate the simultaneous activation of multiple molecules, which is the reason for the high activity. In addition, the core–shell structure also has good substrate suitability and recyclability stability. This study provides good ideas for the development of low-cost heterogeneous ionic liquid catalysts. [ABSTRACT FROM AUTHOR]

In this article, we reported a new strategy to synthesize of isosorbide-based copolycarbonates with good flexibility and tunable thermal property via one-pot direct melt polycondensation of isosorbide (ISB), dimethyl carbonate (DMC) and 1,4-benzenedimethanol (BDM). The effect of different feed ratio on the chemical structure, molecular weight, thermal and mechanical property of copolycarbonates was in-depth studied. A series of metal ion-containing compounds as catalysts were used, and the copolycarbonates was synthesized with weight average molecular weight (Mw) of 80,300 and dispersity index below 1.78 by sodium tert-butoxide catalyst, and the reaction time was shorted to only 3.5 h with the ISB conversion up to 99.0%. Meanwhile, the Tg values realized controllable and tunable from 69 to 164 °C by varying the ratio of two diol monomers, and the influence of the structure of carbonyl carbon in repeating units of copolycarbonates on the thermal properties were demonstrated. Moreover, the results of dynamic mechanical analysis (DMA) implied that the flexibility of copolycarbonates was increased with increasing BDM content, and the results of scratch resistance and melting index of the copolycarbonates provided enormous prospect for the industrial application. Synopsis: A green synthetic pathway for high molecular weight and flexible isosorbide-based copolycarbonate was developed via one-pot melt polycondensation of isosorbide, dimethyl carbonate and 1,4-benzenedimethanol. [ABSTRACT FROM AUTHOR]