This work discloses a zwitterionic approach for selective copolymerization of carbon dioxide (CO 2 ) and propylene oxide (PO), producing poly(propylene carbonate) (PPC), a biodegradable polymer with broad applications. Small-molecule catalysts composed of triethylamine (TEA) and trialkyl boranes are effective for CO 2 / PO copolymerization with an alternating degree of >99% and a productivity of 171 g PPC/g catalyst. A diamine N,N,N′,N′-tetraethyl ethylenediamine (TEED) paired with trialkyl borane exhibited improved activity and productivity (up to 216 g PPC/g catalyst). By adjusting the Lewis acid−base pair, the PPC selectivity can be regulated to 99%. In addition, PPCs have medium regioregularity with a head-to-tail diad content of 80−82% and number-average molecular weights of up to 56.0 kg/mol with narrow polydispersity (below 1.2). The overall catalytic performance of these readily available simple molecules is better than that of previously reported organic catalysts for CO 2 /PO copolymerization. Successive insertion of PO and CO 2 into the Lewis pair leads to the formation of an end-to-end zwitterion featuring a TEB-masked anion and an onium cation, which is highly selective to the alternating copolymerization, as demonstrated by quantum mechanical calculations.

Novel constrained Schiff-base ligands (inden) were developed based on the well-known salen ligands. Chromium complexes supported by the constrained inden ligands were successfully synthesized and used as catalysts for the synthesis of cyclic carbonates from epoxides and carbon dioxide (CO 2 ). The catalyst having tert-butyl ( t Bu) groups as substituents in combination with tetrabutylammonium bromide (TBAB) as a cocatalyst exhibited very high catalytic activity with a turnover frequency of up to 14800 h −1 for the conversion of CO 2 and propylene oxide into propylene carbonate exclusively at 100 °C and 300 psi of CO 2 under solvent-free conditions. The catalyst was found to be highly active for various epoxide substrates to produce terminal cyclic carbonates in 100% selectivity.

Introducing sulfur atoms into polycarbonate can improve its optical properties, but is limited by the lack of efficient synthetic methods. Here we develop a facile method to achieve the one‐pot/one‐step incorporation of sulfur atoms into polycarbonate chains using raw chemicals of propylene oxide (PO), carbon dioxide (CO2), and carbonyl sulfide (COS). The metal‐free Lewis acid–base pair composed of N, N‐dimethylcyclohexylamine combined with triethyl borane can effectively catalyze the terpolymerization of PO, CO2, and COS, affording a sulfur‐containing polycarbonate with high molecular weight (Mn) up to 58.4 kDa and narrow dispersity (Đ = 1.24–1.56). The obtained terpolymers display gradient sequence with tunable thiocarbonate units (27%–81%) upon simply varying the feed ratio of COS. The refractive indices of the terpolymers can be enhanced up to 1.55 at high thiocarbonate content, suggesting promising applications of the terpolymer in optical materials.

An effective route for ring-opening copolymerization of β-butyrolactone (BBL) with ε-decalactone (ε-DL) is reported. Microstructures of the block copolymers characterized by 13 C NMR spectroscopy revealed syndiotactic-enriched poly(3-hydroxybutyrate) (PHB) blocks. Several di- and triblock copolymers (PDL- b -PHB and PDL- b -PHB- b -PDL, respectively) were successfully synthesized by sequential addition of the monomers using (salan)Y(III) complexes as catalysts. The results from MALDI-ToF mass spectrometry confirmed the presence of the copolymers. Moreover, thermal properties of the block copolymers were also investigated and showed that the microphase separation of PDL- b -PHB copolymers into PHB- and PDL-rich domains has an impact on the glass transition temperatures of both blocks.