This paper describes the synthesis of a new biobased bis(cyclic carbonate) derived from 2,5-furandicarboxylic acid (FDCA) with the incorporation of CO2. The bis(cyclic carbonate) was then used to synthesize non-isocyanate polyurethanes (NIPUs) via polyaddition reactions with a series of diamines. The chemical structures of the bis(cyclic carbonate) and the NIPUs were characterized by Fourier transform infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance spectroscopy (1H NMR). The number-average molecular weights (Mn) of the NIPUs were between 3900 g mol−1 and 7000 g mol−1 as determined by gel permeation chromatography (GPC). The thermal properties of the NIPUs were investigated by differential scanning calorimetry (DSC) and thermogravimetric analyses (TGA). The results showed that the NIPUs synthesized in this study had a degradation temperature for 5% weight loss (T5%) in the range of 240 °C and 279 °C, indicating good thermal stability. The NIPUs were also found to be fully amorphous with a broad range of glass transition temperatures (Tg) from 63 °C to 113 °C, depending on the chemical structures of the diamines used. The rigid chemical moiety of cycloaliphatic diamine led to a higher Tg of the NIPUs than the flexible carbon chains of linear aliphatic diamines. This study demonstrated a new method for the synthesis of biobased NIPUs, with satisfactory properties, from FDCA, which is an important platform chemical derived from cellulosic biomass.

Oxalic acid, the cheapest dicarboxylic acid, was used as an effective initiator to synthesize polyols by copolymerization of CO2 and propylene oxide over a zinc–cobalt double metal cyanide catalyst. Generally, reaction times as long as 255 min were observed for complete PO conversion, due to the existence of the free carboxylic acid group of oxalic acid. To overcome this disadvantage, we proposed a novel preactivation approach by formation of oxalic acid based oligo-ether-diol in advance. About 4.75 PO monomers were initiated at 80 °C, which was independent of time and oxalic acid amount; the diol then acted as a chain transfer agent for the following copolymerization. Under the optimal conditions the reaction could proceed to completion in 150 min, which was a remarkable reduction in reaction time compared to the previous reaction time of 255 min. Notably, the resulting CO2-based diol was stable up to 190 °C, indicating that oxalic acid may be applied as an effective initiator for this copolymerization.

Synthesis of polyols from carbon dioxide (CO2) is attractive from the viewpoint of sustainable development of polyurethane industry; it is also interesting to adjust the structure of the CO2-polyols for versatile requirement of polyurethane. However, when renewable malonic acid was used as a starter, the copolymerization reaction of CO2 and propylene oxide (PO) was uncontrollable, since it proceeded slowly (13 h) and produced 40.4 wt% of byproduct propylene carbonate (PC) with a low productivity of 0.34 kg/g. A careful analysis disclosed that the acid value of the copolymerization medium was the key factor for controlling the copolymerization reaction. Therefore, a preactivation approach was developed to dramatically reduce the acid value to ~0.6 mg(KOH)/g by homopolymerization of PO into oligo-ether-diol under the initiation of malonic acid, which ensured the controllable copolymerization, where the copolymerization time could be shortened by 77% from 13 to 3 h, the PC content was reduced by 76% from 40.4 wt% to 9.4 wt%, and the productivity increased by 61% from 0.34 to 0.55 kg/g. Moreover, by means of preactivation approach, the molecular weight as well as the carbonate unit content in the CO2-diol was also controllable.

A trivalent titanium complex combining salen ligand (salen-H2═N,N-bis(3,5-di-tert-butylsalicylidene)-1,2-benzenediamine) was synthesized as catalyst for copolymerization of CO2 and cyclohexene (CHO). In combination with onium salt [PPN]Cl, (Salen)Ti(III)Cl showed impressive activity and selectivity, yielding completely alternating copolymer without the formation of cyclohexene carbonate (CHC), with turnover frequency (TOF) of 557 h–1 at 120 °C, which was more than 10 times higher than that of our previously reported (Salalen)Ti(IV)Cl, and close to the Cr counterparts. In addition to the biocompatibility of Ti, thermally robust character resulting from the reducibility of trivalent Ti was industrially desirable.Keywords: carbon dioxide; copolymerization; cyclohexene oxide; homogeneous catalysis; salen; titanium

An aluminum porphyrin complex with a quaternary ammonium salt cocatalyst exhibits high activity (i.e., a turnover frequency as high as 1.85 × 105 h−1) and selectivity (>99%) for cyclic carbonates synthesis from CO2 and epoxides; the catalyst can be reused at least 4 times with only a slight loss in activity.

A CO2-based oligo(carbonate-ether) tetraol was synthesized in a controlled manner by immortal copolymerization of carbon dioxide (CO2) and propylene oxide (PO) in the presence of 1,2,4,5-benzenetetracarboxylic acid (btcH4) catalyzed by using a zinc–cobalt double metal cyanide (Zn–Co–DMC) catalyst. The number average molecular weight (Mn) of the tetraol was in a good linear relationship with the molar ratio of PO and btcH4 (PO/btcH4), and hence can be precisely controlled. Besides, the rapid chain transfer in immortal copolymerization afforded the tetraol with a narrow polydispersity index (PDI) of 1.08 at a Mn of 1400 g mol−1. Notably, the weight fraction of the byproduct propylene carbonate (WPC) was reduced to as low as 4.0 wt%, which is the lowest Wpc ever reported for the synthesis of branched polyols. The structure of the oligo(carbonate-ether) tetraol was confirmed, providing new evidence for the effect of the acidity (pKa1 value) of the chain transfer agent (CTA) on the initial catalytic mechanism. The acid only acts as the CTA directly participating in the copolymerization via the chain transfer reaction when its pKa1 value is higher than that of adipic acid (pKa1 = 4.43). However, when its pKa1 value is lower than that of succinic acid (pKa1 = 4.2), it acts as the initiate-transfer agent, which first initiates PO homopolymerization to an oligo-ether polyol, and then the in situ formed polyol acts as a new CTA for the copolymerization.

Amorphous poly(propylene carbonate) (PPC) is brittle at room temperature, but the studies related to the toughening of PPC is rare. Herein, two types of polyurethane (PCO2PU) synthesized from a CO2-based diol and toluene diisocyanate were used as rubbery particles to toughen PPC. The notched impact strength of PPC increased from 20.8 J m−1 to 54.2 J m−1 at a PCO2PU loading of 20 wt%, comparable with that of neat nylon 6, and reached 228.3 J m−1 at a PCO2PU loading of 30 wt%, 10.9 fold that of neat PPC and even higher than bisphenol A polycarbonate. Matrix yielding as well as cavitation was observed during the impact process, which was responsible for the increase of impact strength. Moreover, the toughening efficiency was related with the carbonate content of PCO2PU, and the transition of fracture behavior from brittle to ductile occurred when the PCO2PU with a weight average diameter of 0.20 μm was uniformly dispersed in PPC substrate.

A novel conjugated microporous polymer was solvothermally synthesized using an aluminum porphyrin as a main building block, which had a high Brunauer–Emmett–Teller specific surface area up to 839 m2 g−1 and a pore volume of 2.14 cm3 g−1. The polymer displayed excellent capacity to capture carbon dioxide (4.3 wt%) at 273 K and 1 bar, and good catalytic activity for cyclic carbonate synthesis with TOF up to 364 h−1.

•Non-isocyanate polyurethane (NIPU) was synthesized and used to toughen PPC.•The transition of PPC from brittle to marginally tough occurred.•Equilibrium between two kinds of hydrogen bonding affected the miscibility.To overcome the brittleness of poly(propylene carbonate) (PPC), rubbery non-isocyanate polyurethane (NIPU) with rich hydrogen bonding moiety was synthesized for toughening PPC. Debonding phenomenon of NIPU was observed during the impact process of PPC/NIPU blends, which was beneficial for toughening PPC. When the NIPU loading increased to 10 wt%, the unnotched impact strength increased 3 times compared with neat PPC. The NIPU dispersed uniformly and a transition from brittle to marginally tough occurred when L/d reached a critical value, 1.74, where L and d were center-to-center distance and the diameter of the particle, respectively. The debonding of NIPU accounted for the increase of toughness, and shear yielding of the matrix was limited around the microvoids. When the NIPU loading reached 13 wt%, NIPU flocculated in the matrix leading to decline in toughness. The equilibrium between self-associating hydrogen bonding and intermolecular one formed between PPC and NIPU affected their miscibility and thereby the morphology of the blends.