Cyclic Monomers Research Articles

Synergistic enhancement of poly(lactide) melt strength via copolymerization and multi-arm branching strategy

The lower melt strength of poly(lactide) (PLA) limits its broader applications. Here, a strategy combining copolymerization with multi-arm branching was propose to enhance the melt strength of PLA. Initially, stereoisomeric cyclic ester monomers (CEM) synthesized via zeolite catalysis were copolymerized into PLA chains. Subsequently, rheological testing revealed that the zero-shear viscosity (η0) of linear PLA increased by 467 % with only 1 mol% of CEM units. Our study further systematically explored the relationship between the side group structure and chirality of the comonomers and the rheological properties of the copolymers. CEMs with long-chain branched structures and opposite chirality had the best enhancement effect. In order to further enhance the melt strength, we successfully achieved alterations in polymer topology by employing trimethylolpropane as an initiator, corresponding three-arm copolymers achieve up to a 67-fold increase in η0 (1.0 kPa∙s to 68.1 kPa∙s). Tensile tests indicated that the mechanical properties of the copolymers were comparable to those of PLA, with a tensile strength of approximately 65 MPa. Additionally, due to the high melt strength, we successfully produced closed-cell PLA-based foam materials with uniform pore sizes. In summary, this study furnishes a feasible method for designing polymer materials possessing the desired melt strength.

Polyalkenamers as Drop-In Additives for Ring-Opening Metathesis Polymerization: A Promising Upcycling Paradigm.

We report a distinct strategy to upcycle waste polyalkenamers such as polybutadiene into new, performance-advantaged materials by using them as drop-in additives for ring-opening metathesis polymerization (ROMP). The polyalkenamers serve as competent chain-transfer agents in ROMPs of common classes of cyclic olefin monomers, facilitating good molecular weight control, allowing low Ru catalyst loadings, and enabling efficient incorporation of the polyalkenamer into the synthesized polymeric material. We successfully demonstrate ROMP using model polyalkenamers and translate these learnings to leverage commercial polybutadiene and acrylonitrile butadiene styrene (ABS) as chain transfer agents for ROMP copolymerizations. Critically, our strategy is shown to be highly efficient and operationally simple, quantitatively incorporating the polyalkenamer and inheriting aspects of its thermomechanical performance. Our results highlight a promising pathway for the upcycling of polyalkenamers and provide an alternative to existing deconstruction and functional upcycling strategies.

Facile and Efficient Synthesis of Fluorosilicone Polymers by Using an Optimized Gradient Ring-Opening Reaction.

Fluorosilicone rubber is essential for sealing in extreme temperatures and non-polar environments due to its exceptional adaptability. However, achieving a high yield of fluorosilicone polymers with medium and high fluorine content remains a challenge. Herein, a facile gradient strategy is developed that involves modifying the method of cyclic monomer addition based on the rate of ring-opening polymerization (ROP), to improve yield and adjust fluorine content precisely. The polymerization process is designed and tailored based on the reaction rates of anionic ring-opening polymerization (AROP) and cationic ring-opening polymerization (CROP) via an efficient gradient strategy. The effects of the polymerization process on the viscosity and yield of vinyl fluorosilicone polymers and hydrofluorosilicone polymers are investigated and optimized. Notably, the as-prepared vinyl-terminated fluoromethylsilane with 60% fluorine content (FMS-Vi-60F) has a high yield (86.6%) and high viscosity (150000 mPa·s) in a short reaction time, which is superior to previous methods. Clearly, the gradient ring-opening method developed in this work provides a facile and efficient synthesis for fabricating fluorosilicone polymers with a high yield and tunable fluorine content.

Allylic Epoxides Increase the Strain Energy of Cyclic Olefin Monomers for Ring-Opening Metathesis Polymerization.

Ring-opening metathesis polymerization (ROMP) is an effective method for synthesizing functional polymers, but since the technique typically relies on high ring strain cyclic olefins, the most common monomers are norbornene derivatives. The reliance on one class of monomer limits the obtainable properties of ROMP polymers. In this work, we investigate new bicyclic monomers synthesized via epoxidation of commercial dienes. DFT estimates of these monomers' ring strains suggests a significant increase in strain for cyclic olefins containing allylic epoxides. We found that the eight-membered (3,4-COO) and five-membered (CPO) cyclic olefins were particularly effective for ROMP. CPO was of especially intriguing due to its excellent polymerizability when compared to the limited reactivity of other five-membered rings. Unlike polynorbornenes, the resulting polymers of both monomers displayed glass transition temperatures well below room temperature. Interestingly, poly(3,4-COO) showed both high stereo- and regioregularity while poly(CPO) showed little regularity. Both polymers could be readily modified via post-polymerization ring-opening of the reactive allylic epoxides. With a high epoxide density in poly(CPO), CPO is an exciting new ROMP monomer that is easily synthesized, can be polymerized to high conversion at room temperature, and may be facilely modified to yield a wide range of functional materials.

Allylic Epoxides Increase the Strain Energy of Cyclic Olefin Monomers for Ring‐Opening Metathesis Polymerization

Ring‐opening metathesis polymerization (ROMP) is an effective method for synthesizing functional polymers, but since the technique typically relies on high ring strain cyclic olefins, the most common monomers are norbornene derivatives. The reliance on one class of monomer limits the obtainable properties of ROMP polymers. In this work, we investigate new bicyclic monomers synthesized via epoxidation of commercial dienes. DFT estimates of these monomers’ ring strains suggests a significant increase in strain for cyclic olefins containing allylic epoxides. We found that the eight‐membered (3,4‐COO) and five‐membered (CPO) cyclic olefins were particularly effective for ROMP. CPO was of especially intriguing due to its excellent polymerizability when compared to the limited reactivity of other five‐membered rings. Unlike polynorbornenes, the resulting polymers of both monomers displayed glass transition temperatures well below room temperature. Interestingly, poly(3,4‐COO) showed both high stereo‐ and regioregularity while poly(CPO) showed little regularity. Both polymers could be readily modified via post‐polymerization ring‐opening of the reactive allylic epoxides. With a high epoxide density in poly(CPO), CPO is an exciting new ROMP monomer that is easily synthesized, can be polymerized to high conversion at room temperature, and may be facilely modified to yield a wide range of functional materials.

Recent Advances in the Development of 1,4-Cyclohexanedimethanol (CHDM) and Cyclic-Monomer-Based Advanced Amorphous and Semi-Crystalline Polyesters for Smart Film Applications.

Polyester-based advanced thin films have versatile industrial applications, especially in the fields of textiles, packaging, and electronics. Recent advances in polymer science and engineering have resulted in the development of advanced amorphous and semi-crystalline polyesters with exceptional performance compared to those of conventional polymeric films. Among these, 1,4-cyclohexanedimethanol (CHDM) and cyclic-monomer-based polyesters have gained considerable attention for their exceptional characteristics and potential applications in smart films. This review article provides a comprehensive overview of the recent advances in the synthesis, characterization, and applications of CHDM and cyclic-monomer-based advanced polymers for smart film applications. It discusses the structure-property relationships of these innovative polyesters and highlights their unique characteristics, including thermal, mechanical, and barrier characteristics. Furthermore, this article also emphasizes the solution, melt, and solid-state polymerizations of the polymers. Special emphasis is placed on the influence of the addition of a second diol or second diacid on the performance characteristics of synthesized polyesters/copolyesters to explore their versatile industrial applications. Additionally, the impact of the stereochemistry of the monomers is explored to optimize the characterization of polyesters suitable for industrial applications. Furthermore, this article explores the potential of these advanced polyesters to be considered as materials for smart film applications, especially in the field of flexible electronics. Finally, this article examines the challenges and future recommendations for the development of CHDM and cyclic-monomer-based polyesters for smart film applications. It discusses potential avenues for further research, including in-depth studies for the synthesis and characterization of polyesters, the development of sustainable and biodegradable alternatives to cyclic monomers, alternative green approaches for the synthesis of polymers, etc. This review article provides valuable insight for researchers in academia and industry who are working in the fields of polymer science and materials engineering.

Combining linear and cyclic sulfones as a strategy for elaborating more efficient high-dielectric polymer materials: A second case of dipolar glass copolymers

Motivated by the excellent features exhibited by sulfone functional groups in the development of high-dielectric polymer materials, this work assesses the combination of linear and cyclic sulfone structures through copolymerization to prepare novel polymer materials exhibiting high dielectric constants (ԑr'), low dissipative behavior, and improved thermal properties. Five new polymethacrylate-based copolymers with varying compositions were synthesized through reversible addition-fragmentation chain transfer (RAFT) polymerization. The correct structure and macromolecular nature of the devised materials were confirmed by infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (1H/13C NMR), and gel permeation chromatography (GPC), while their thermal properties were evaluated using thermogravimetry analysis (TGA) and differential scanning calorimetry (DSC). All specimens exhibited adequate thermal properties for most capacitor applications in terms of onset degradation (Ti) and glass transition (Tg) temperatures. All materials degraded well above 250 °C, with increased Ti and Tg values depending on the final composition of the cyclic sulfone monomer in the material. The incorporation of cyclic sulfones not only increased the thermal robustness of the specimens but also raised their Tg values to as high as 189 °C, notably expanding the range of temperatures where these systems can operate without dissipative phenomena. More importantly, broadband dielectric spectroscopy (BDS) revealed that all samples exhibited dielectric properties notably superior to those of conventional polymer materials, with high ԑr' values between 6.0 and 8.9 (at 25 °C and 1 Hz) and low loss factors (Tan(δ) < 0.018). Overall, the present work successfully demonstrates the advantages of including cyclic structures with high dipole moments in polymeric backbones, offering a new strategy to enhance the thermal and dielectric properties of high-dielectric polymer materials.

-Effects and mechanisms of acrylamide-based polymer containing N-vinylpyrrolidone on drilling fluids at high temperature

The exploration of ultra-deep oil and gas presents higher temperature resistance requirements for water-based drilling fluids. However, the lack of temperature resistance mechanism of drilling fluid polymers limits the development of key materials and drilling fluids. In this paper, by comparing the preparation of acrylamide polymers for drilling fluids, the influence of cyclic monomer N-vinylpyrrolidone (NVP) on the properties of polymers for drilling fluids was investigated, and the mechanism of NVP was deeply discussed. The results show that the NVP-containing copolymer PAAN has superior viscosity enhancement and filtration control in high-temperature drilling fluids. This is mainly due to the fact that PAAN has a more stable and complex polymer chain structure than PAA, the polymer that does not contain NVP, and its thermal stability is improved by 18.6 % up to 268°C. At the same time, NVP provides more adsorption spots, and the high-temperature clay adsorption capacity of PAAN in drilling fluids is increased by more than 66.9 % compared with that of PAA, which improves clay hydration and promotes clay dispersion, and ultimately reduces filtration of drilling fluids and stabilizes drilling fluids at high temperatures by more than 23.7 %. The introduction of NVP and the in-depth analysis of its action mechanism supplemented the anti-temperature mechanism of drilling fluid polymers, aiming to support the research and development of ultra-deep drilling fluid technology.

Visible light-driven organocatalyzed radical ring-opening polymerization of Bicyclo[1.1.0]butanes

Radical ring-opening polymerization (rROP) offers an essentially practical strategy to introduce a broad scope of functional groups in the polymer backbone. While suitable cyclic monomers mostly possess a vinyl group to facilitate the radical addition step, we herein present an efficient rROP of highly strained bicyclo[1.1.0]butane (BCB)-derived monomers through radical addition to bridge σ-carbon–carbon bond by photoinduced electron/energy transfer reversible addition−fragmentation chain transfer (PET-RAFT) polymerization technique, producing poly(BCBs) with relatively predictable molecular wight and low to moderate dispersity. Spatiotemporal control over the polymer chain-growth was achieved and high chain-end fidelity was imparted to access intriguing random and block copolymers with complex structures.

Enhancing the incorporation of 2-methylen-1,3-dioxepane (MDO) into industrial monomers by the addition of crotonate comonomers

Environmental concerns are pushing towards more sustainable materials such as degradable or bio-based polymers. 2-methylen-1,3-dioxepane (MDO) is a cyclic ketene acetal monomer that when reacts by radical ring opening polymerization can introduce degradable ester groups in the polymer backbone, but it is generally challenging to incorporate it uniformly with other industrially relevant vinylic monomers such as styrenics, methacrylics, acrylics and vinylics. In this work, we explore the use of butyl crotonate as termonomer to enhance the incorporation of MDO into common industrial monomers taking advantage of the particular reactivities of MDO and crotonate. Styrene is found not suitable for terpolymerization, as it just homopolymerized. With methyl methacrylate, the incorporation of MDO is substantially enhanced due to the presence of BCr, but the terpolymer is not homogeneous, and MDO is primarily incorporated in the closed form, which only partially enhanced the degradability. In the terpolymerization with ethyl acrylate high MDO incorporation is achieved (up to 80 %) and most of it is incorporated in to the open formed (80 %). Therefore, the obtained terpolymer shows complete degradation in 28 days. Last, the terpolymerization of vinyl acetate is the most successful, as almost total conversion of all monomers is achieved in short times, including (100 % conversion of MDO). Furthermore, the obtained terpolymers are highly homogeneous and degraded completely in few hours. The addition of crotonate monomer in formulations where MDO or other cyclic ketene acetal could bring new insights as it is shown that not only the incorporation of cyclic ketene acetals is enhanced but also that it favors the incorporation into the open form, which substantially enhanced the degradability of common polymers produced by radical polymerization.

Bioinspired Binding and Conversion of Linear Monoterpenes by Polyaromatic Coordination Capsules.

Linear monoterpenes, versatile reaction biosubstrates, are bound and subsequently converted to various cyclic monomers and oligomers with excellent selectivity and efficiency, only in natural enzymes. We herein report bioinspired functions of synthetic polyaromatic cavities toward linear monoterpenes in the solution and solid states. The cavities are provided by polyaromatic coordination capsules, formed by the assembly of Pt(II) ions and bent bispyridine ligands with two anthracene panels. By using the capsule cavities, the selective binding of citronellal from mixtures with other monoterpenes and its preferential vapor binding over its derivatives are demonstrated in water and in the solid state, respectively. The capsule furthermore extracts p-menthane-3,8-diol, with high product- and stereoselectivity, from a reaction mixture obtained by the acid-catalyzed cyclization of citronellal in water. Thanks to the inner and outer polyaromatic cavities, the catalytic cyclization-dimerization of vaporized citronellal efficiently proceeds in the acid-loaded capsule solid and product/stereoselectively affords p-menthane-3,8-diol citronellal acetal (∼330% yield based on the capsule) under ambient conditions. The solid capsule reactor can be reused at least 5 times with enhanced conversion. The present study opens up a new approach toward mimicking terpene biosynthesis via synthetic polyaromatic cavities.

Ring-opening polymerization of six-membered cyclic hybrid dimers composed of an oxoester and thioester

Three cyclic oxoester-thioester hybrid monomers, 1 (3-methyl-1,4-oxathiane-2,5-dione), 2 (6-methyl-1,4-oxathiane-2,5-dione), and 3 (3,6-dimethyl-1,4-oxathiane-2,5-dione), were studied for anionic and cationic ring-opening polymerizations. These monomers are six-membered cyclic cross-dimers corresponding to combinations of glycolic and lactic acids with their thiol analogs. Anionic polymerizations using thiol as the initiator and 2,6-lutidine as the base catalyst were successful for the chemoselective cleavage of the thioester with the thiol propagating end. The polymerizability increased in the order of 3 < 1 < 2, which was in good agreement with the increasing ring strain order evaluated by Density Functional Theory calculations. The living character, to some extent, was suggested by the postpolymerization reactions, which involved a two-stage feed of the monomers and a thiol-ene terminal coupling reaction to form a block copolymer with PEG. Additionally, it was found that the polymerization took place in 2,6-lutidine without a thiol initiator and produced macrocyclic polymers. The cationic polymerizations took place with the aid of CF3SO3H and benzyl alcohol but involved side reactions with low chemoselective ring cleavage. The thioester unit caused the polymers to exhibit a lower Tg with greater thermal and photo degradability.

Ring‐opening (co)polymerization strategies of selected oxacyclic monomers to control and provide tailored polymers with desired properties

AbstractRing‐opening polymerization (ROP) is a versatile synthetic method used to produce polymers from cyclic monomers, particularly oxacyclic monomers such as lactones and cyclic ethers. Oxacyclic monomers polymerize with anionic or cationic initiators. For selected monomers, such as glycidol, β‐butyrolactone and higher lactones, methods, and mechanisms of polymerization are presented, the understanding of which has allowed control of these processes. The use of appropriate polymerization techniques and methods, as well as conducting the copolymerization, mainly block copolymerization, makes it possible to control the architecture, molar mass, and end groups of the resulting polymers. These parameters determine the properties of macromolecules, such as solubility, ability to aggregate in aqueous solutions, thermoresponsiveness, and degradability. By carefully selecting monomers, catalysts, and polymerization conditions, ROP strategies can be tailored to produce polymers with precise molecular structures and desired properties for a wide range of applications. This review mainly focuses on precisely controlled syntheses that lead to well‐defined macromolecules consisting mostly of polyether and/or polyester chains.

PEG-functionalized aliphatic polycarbonate brushes with self-polishing dynamic antifouling properties

Hydrophilic antifouling polymers provide excellent antifouling effects under usual short-term use conditions, but the long-term accumulation of contaminants causes them to lose their antifouling properties. To overcome this drawback, surface-initiated ring-opening graft polymerization (SI-ROP) was performed on the surface of the material by applying the cyclic carbide monomer 4′-(fluorosulfonyl)benzyl-5-methyl-2-oxo-1,3-dioxane-5-carboxylate (FMC), which contains a sulfonylfluoride group on the side chain, followed by a “sulfur(IV)-fluorine exchange” (SuFEx) post click modification reaction to link the hydrophilic polyethylene glycol (PEG) to the polyFMC (PFMC) brush, and a novel antifouling strategy for self-polishing dynamic antifouling surfaces was developed. The experimental results showed that the antifouling surface could effectively prevent the adsorption of proteins such as bovine serum albumin (BSA, ∼96.4%), fibrinogen (Fg, ∼87.8%) and lysozyme (Lyz ∼69.4%) as well as the adhesion of microorganisms such as the bacteria Staphylococcus aureus (S. aureus) (∼87.5%) and HeLa cells (∼67.2%). Moreover, the enzymatically self-polished surface still has excellent antifouling properties. Therefore, this modification method has potential applications in the field of biosensors and novel antifouling materials.

Polyheptenamer: A chemically recyclable polyolefin enabled by the low strain of seven‐membered cycloheptene

AbstractLow‐strain cyclic olefin monomers, including five‐membered, six‐membered, eight‐membered, and macrocyclic rings, have been recently exploited for the synthesis of depolymerizable polyolefins via ring‐opening metathesis polymerization (ROMP). Such polyolefins can undergo ring‐closing metathesis depolymerization (RCMD) to regenerate their original monomers. Nevertheless, the depolymerization behavior of polyolefins prepared by ROMP of seven‐membered cyclic olefins, an important class of low‐strain rings, still remains unexplored. In this study, we demonstrate the chemical recycling of polyheptenamers to cycloheptene under standard RCMD conditions. Highly efficient depolymerization of polyheptenamer was enabled by Grubbs' second‐generation catalyst in toluene. It was observed that the monomer yields increased when the depolymerization temperature increased and the starting polymer concentration was reduced. A near‐quantitative monomer regeneration (&gt;96%) was achieved within 1 h under dilute conditions (20 mM of olefins) at 60°C. Moreover, polyheptenamer exhibited a decomposition temperature above 430°C, highlighting its potential as a new class of thermally stable and chemically recyclable polymer materials.

Polymers from Plant Oils Linked by Siloxane Bonds for Programmed Depolymerization.

The increased production of plastics is leading to the accumulation of plastic waste and depletion of limited fossil fuel resources. In this context, we report a strategy to create polymers that can undergo controlled depolymerization by linking renewable feedstocks with siloxane bonds. α,ω-Diesters and α,ω-diols containing siloxane bonds were synthesized from an alkenoic ester derived from castor oil and then polymerized with varied monomers, including related biobased monomers. In addition, cyclic monomers derived from this alkenoic ester and hydrosiloxanes were prepared and cyclized to form a 26-membered macrolactone containing a siloxane unit. Sequential ring-opening polymerization of this macrolactone and lactide afforded an ABA triblock copolymer. This set of polymers containing siloxanes underwent programmed depolymerization into monomers in protic solvents or with hexamethyldisiloxane and an acid catalyst. Monomers afforded by the depolymerization of polyesters containing siloxane linkages were repolymerized to demonstrate circularity in select polymers. Evaluation of the environmental stability of these polymers toward enzymatic degradation showed that they undergo enzymatic hydrolysis by a fungal cutinase from Fusarium solani. Evaluation of soil microbial metabolism of monomers selectively labeled with 13C revealed differential metabolism of the main chain and side chain organic groups by soil microbes.

Effects of Humidity and Produced Water on Specific Adsorption of High Oxygen Permeability Ionomers Composed Entirely of Cyclic Monomers on Cathode Performance for Polymer Electrolyte Fuel Cells

Effects of Humidity and Produced Water on Specific Adsorption of High Oxygen Permeability Ionomers Composed Entirely of Cyclic Monomers on Cathode Performance for Polymer Electrolyte Fuel Cells

Study of a high salt tolerant amphiphilic polymer and its salt thickening mechanism

Polymer flooding is the most reliable method for the petroleum industry to further enhance oil recovery from the developed oil field and to keep the total oil production. For the reservoirs with high salinity, traditional polymer fluids, for example partially hydrolyzed polyacrylamide (HPAM), are failed to improve oil recovery rate due to the molecular agglomeration caused by compression-diffusion electric double layer. By optimizing the copolymerization of cyclic structure monomer n-vinylpyrrolidone (NVP) and long-chain hydrophobic monomer cetyl dimethyl allyl ammonium chloride (C16DMAAC), a high salt tolerant amphiphilic polymer P(AM/NVP/C16DMAAC), abbreviated as PANC, is synthesized. The optimal polymerization conditions were determined depending on the apparent viscosity measured by the rheometer. The microstructure of the polymer was evaluated using Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy and scanning electron microscopy. The viscosity of 2000 mg/L PANC increased to 42.7 mPa·s at the salinity of 11.6 × 104 mg/L and temperature of 40 °C, while the viscosity of HPAM was only 7.3 mPa·s under the same condition. The viscosity of PANC was 479 % higher than that of HPAM, indicating the remarkable salt tolerant property of PANC. The viscosity of PANC increased from 12 mPa·s to 42.7 mPa·s when the salinity increased from 1 × 104 mg/L to 11.6 × 104 mg/L. By comparing the salt resistance of polymer PANC and polymer P(AM/AA/C16), abbreviated as AP-C16, indicating that NVP enhanced the rigidity of the PANC molecular chain, and hindered the shrinkage and curling of the molecular chain after salt addition. The inclusion effect of β-cyclodextrin on the hydrophobic groups of PANC indicated that PANC increased viscosity through the hydrophobic association of C16DMAAC. Furthermore, PANC showed a salt thickening ability due to the synergy effect of C16DMAAC and NVP. As such, the salt tolerant amphiphilic polymer PANC offers a novel polymer flooding material for oil displacement, especially under a high-salinity condition.

PH/GSH-responsive diselenide-containing micelle via backbone ketoxime cross-links for efficient drug delivery and controlled release

Stimulus-responsive polymers are promising drug delivery systems for cancer therapy. However, low drug loading and drug leakage of polymeric carriers remain challenges. Here, a crosslinked diselenide-containing micelle was developed with pH/GSH dual responsiveness. Polyesters with multiple diselenide bonds and pendant ketone groups were synthesized by the ring-opening copolymerization of three cyclic monomers (diselenide-containing macrocyclic carbonate, 2-oxepane-1,5-dione, and 1,3-dioxan-2-one). The crosslinked polyester was obtained by the oxime click reaction of pendant ketone groups with hydroxylamine and then self-assembled into crosslinked micelle. This crosslinked micelle remained stable for 14 days, and responded to disassembly under the condition of pH = 5.0 and 10 mM glutathione (GSH). When the crosslinked micelle was loaded with the chemotherapeutic drug DOX, which possessed an active ketone group, the encapsulation efficiency of the crosslinked micelle increased to 91.36 %. The cumulative DOX release reached approximately 45 % under pH = 5.0 and 10 mM GSH. Importantly, the crosslinked diselenide-containing micelle could be taken up in MCF-7 breast cancer cells, responding to the tumor microenvironment and releasing encapsulated DOX. This crosslinked diselenide-containing micelle with pH/GSH dual responsiveness was proven to be a stable and efficient carrier with a promising application.

CO2 and Lignin‐Based Sustainable Polymers with Closed‐Loop Chemical Recycling

AbstractThis work highlights the conversion method of chaining up greenhouse gas CO2 with biomass lignin to develop new sustainable, recyclable polymers from abundant and non‐food based renewable resources. A cyclic carbonate monomer has synthesized using a cost‐effective, non‐phosgene‐based, and greener approach under atmospheric pressure and room temperature. The fully programable ring‐opening polymerization is accomplished by varying the catalyst (DBU and TBD), catalyst loading (0.5–5.0%) and reaction time (2–40 min). The best polymer is obtained in 1% TBD with a 30‐min reaction. The precise characterization of the synthesized cyclic carbonate monomer and polymers' structure are established using spectroscopic analyses including 1H, 13C, and 2D HSQC NMR, FT‐IR, and GPC. The new polymers exhibit high molecular weights (Mn: 120.34–154.58 kDa) and adequate thermal stabilities (Td5%: 244–277 °C from TGA and Tg: 33–52 °C from DSC), rendering them advantageous for practical applications. Significantly, the CO2 and lignin‐based polymers have successfully recycled to the monomer for a circular plastic economy by heating at 90 °C for 12 h in the presence of DBU. This process yields original monomers for another polymerization without unwanted changes in chemical structures, presenting an ultimate sustainable solution.