Biodegradable polycarbonates from lignocellulose based 4-pentenoic acid and carbon dioxide

The production of biodegradable polycarbonate by copolymerizing CO₂ with epoxides has emerged as an effective method to utilize CO₂ in response to growing concerns about CO₂ emissions and plastic pollution. Previous studies have mainly focused on the preparation of CO₂-based polycarbonates from petrochemical-derived propylene oxide (PO) or cyclohexene oxide (CHO). However, to reduce dependence on fossil fuels, the development of 100% bio-based polymers has gained attention in polymer synthesis. Herein, we reported the synthesis of glycidyl 4-pentenoate (GPA) from lignocellulose based 4-pentenoic acid (4-PA), which was further copolymerized with CO₂ using a binary catalyst SalenCoCl/PPNCl to produce bio-based polycarbonates with vinyl side chains and molecular weights up to 17.1 kg/mol. Introducing a third monomer, PO, allows for the synthesis of the GPA/PO/CO₂ terpolymer, and the glass transition temperature (T _g) of the terpolymer can be adjusted from 2°C to 19°C by controlling the molar feeding ratio of GPA to PO from 7:3 to 3:7. Additionally, post-modification of the vinyl side chains enables the production of functional polycarbonates, providing a novel approach to the preparation of bio-based materials with diverse side chains and functions.

Cross-Linked Networks in Poly(propylene carbonate) by Incorporating (Maleic Anhydride/cis-1,2,3,6-Tetrahydrophthalic Anhydride) Oligomer in CO2/Propylene Oxide Copolymerization: Improving and Tailoring Thermal, Mechanical, and Dimensional Properties

Poly(propylene carbonate) (PPC) from CO₂ and propylene oxide (PO) has wide potential applications as a degradable "plastic". However, the thermal stability and mechanical properties of PPC cannot meet most of the application requirements. Herein, we focus on improving these properties. A (maleic anhydride/cis-1,2,3,6-tetrahydrophthalic anhydride) (MA/THPA) oligomer containing several cyclocarboxylic anhydride groups, which can copolymerize with PO, has been readily synthesized and used as the third comonomer to prepare PPC with cross-linked networks. The gel contents increase from 16 to 42% with increasing MA/THPA oligomer feed contents from 0.5 to 4 wt % of PO. The formation of cross-linked networks in PPC greatly improves the thermal, mechanical, and dimensional properties. The 5% weight-loss degradation temperature increases from 217 °C to nearly 290 °C before and after cross-linking, which ensures that PPC does not decompose in melt processing. The tensile strength of the copolymer is in the range of 22.2-44.3 MPa with elongation at break of 11-312%. The maximum tensile strength is improved by 143% compared to that of PPC. When the MA/THPA oligomer feed is above 3 wt % of PO, the hot-set elongation of the copolymer at 65 °C decreases more than 10 times when compared with that of PPC, and the permanent deformation is close to 0, while it is 145% for PPC. The dimensional stability is improved sharply. It can overcome the cold flow phenomenon of PPC. The improvement of the above comprehensive properties is of great significance to the practical application of PPC in various fields.

Enhanced Poly(propylene carbonate) with Thermoplastic Networks: A Cross-Linking Role of Maleic Anhydride Oligomer in CO2/PO Copolymerization

Cross-linking is an effective way to enhance biodegradable poly(propylene carbonate) (PPC) from CO₂ and propylene oxide (PO). Cross-linked PPC can be prepared by one-step terpolymerization of multifunctional third monomers with CO₂ and PO. However, few such third monomers are available. Each molecule of maleic anhydride oligomer (MAO) contains more than two cyclic anhydride groups. Here, we use it to synthesize PPC with cross-linked networks by adding a small quantity of MAO (0.625-5 wt% of PO) in CO₂/PO copolymerization that was catalyzed by zinc glutarate. The formation of networks in the prepared copolymers was confirmed by the presence of gel in copolymers combined Fourier transform infrared spectroscopy (FT-IR), ¹H NMR, and the improved mechanical properties. The 5% weight-loss degradation temperatures and maximum weight-loss degradation temperatures greatly increase up to 289.8 °C and 308.8 °C, respectively, which are remarkably high when compared to those of PPC. The minimum permanent deformation of the copolymers closes to 0, while that of PPC is 173%. The maximum tensile strength of the copolymers is 25.5 MPa higher than that of PPC, reaching 38.4 MPa, and it still has some toughness with the elongation at break of 25%. The above phenomena indicate that MAO that was inserted in PPC chains play a cross-linking role, which results in enhanced thermal stability, dimensional stability, and mechanical strength, comprehensively.

A Novel One-Pot Synthesis of Poly(Propylene Carbonate) Containing Cross-Linked Networks by Copolymerization of Carbon Dioxide, Propylene Oxide, Maleic Anhydride, and Furfuryl Glycidyl Ether

The thermoplastic poly(propylene carbonate) (PPC) containing cross-linked networks was one-pot synthesized by copolymerization of carbon dioxide, propylene oxide (PO), maleic anhydride (MA), and furfuryl glycidyl ether (FGE). The copolymers were characterized by Fourier transform infrared spectroscopy (FT-IR), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) measurements. The thermal and dimensional stability of the copolymers were improved. When the MA and FGE load increased from 1 mol% to 4 mol% of PO, the copolymers contained the gel contents of 11.0%-26.1% and their yields were about double that of the PPC. The 5% weight-loss degradation temperatures (Td,-5%) and the maximum weight-loss degradation temperatures (Td,max) increased from 149.7-271.3 °C and from 282.6-288.6 °C, respectively, corresponding to 217.1 °C and 239.0 °C of PPC. Additionally, the hot-set elongation tests showed that the copolymers exhibited elasticity and dimensional stability with the minimum permanent deformation of 6.5% which was far less than that of PPC of 157.2%, while the tensile strengths were a little lower than that of PPC because of the following two conflicting factors, cross-links and flexibility of the units formed by the introduced third monomers, MA and FGE. In brief, we provide a novel method of one-pot synthesis of PPC containing cross-linked networks. According to this idea, the properties would be more extensively regulated by changing the cross-linkable monomers.

Crystalline CO2 -Based Aliphatic Polycarbonates with Long Alkyl Chains

Carbon dioxide (CO₂ ) is an easily available, renewable carbon source and can be utilized as a comonomer in the catalytic ring-opening polymerization of epoxides to generate aliphatic polycarbonates. Dodecyl glycidyl ether (DDGE) is copolymerized with CO₂ and propylene oxide (PO) to obtain aliphatic poly(dodecyl glycidyl ether carbonate) and poly(propylene carbonate-co-dodecyl glycidyl ether carbonate) copolymers, respectively. The polymerization proceeds at 30 °C and high CO₂ pressure utilizing the established binary catalytic system (R,R)-Co(salen)Cl/[PPN]Cl. The copolymers with varying DDGE:PO ratios are characterized via NMR, FT-IR spectroscopy, and SEC, exhibiting high molecular weights between 11 400 and 37 900 g mol^-1 with dispersities (Р= M _w /M _n ) in the range of 1.37-1.61. Copolymers with T _g s of -11 °C or T _m s from 5 to 15 °C and thermal decomposition >200 °C depending on the comonomer ratio, are obtained as determined by differential scanning calorimetry/TGA.

Enhanced Poly(Propylene Carbonate) with Thermoplastic Networks: A One-Pot Synthesis from Carbon Dioxide, Propylene Oxide, and a Carboxylic Dianhydride

Thermally and mechanically enhanced poly(propylene carbonate) (PPC) with networks was prepared by adding a cyclic carboxylic dianhydride, bicyclo(2,2,2)oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (BTCDA), in the CO₂/propylene oxide (PO) copolymerization. The obtained copolymers were characterized by FT-IR, ¹H NMR, DSC, and TGA. The gel, melt flow rate, hot-set elongation, and tensile properties were also measured. The formation of networks was confirmed by the presence of gel and the shape recovery after the hot-set elongation test. The minimum permanent deformation of the copolymer is 3.8% and that of PPC is 4539% higher than this value. The results show that BTCDA units are inserted into the backbone of PPC, and the PPC chains are connected successfully owing to cyclic multifunctional anhydride groups in BTCDA. With increasing feed molar ratio of BTCDA to PO from 1 to 4%, the yield strength of copolymers increases from 18.1 to 37.4 MPa compared to 12.9 MPa of PPC. The 5% weight-loss degradation temperatures and maximum weight-loss degradation temperatures greatly increase up to 276.4 and 294.7 °C, respectively, which are 58.6 °C and 55.1 °C higher than those of PPC. These enhanced properties originate from the formation of crosslinks by the rigid and bulky multifunctional dianhydride.

Synthesis of fully alternating polycarbonate with low Tg from carbon dioxide and bio-based fatty acid

Perfectly alternating copolymerization of CO₂ with a bio-based epoxide is reported with a heterogeneous Zn–Co(iii) DMCC, affording copolymers with low T_g values of −38 to −44 °C and two end hydroxyl groups.