Sustainable Polymer & Energy Open Access

Synthesis and Characterization of Cyclic Carbonate End-Functional Linear and Star Polyesters via Ring-Opening Polymerization

Well-defined α-(cyclic carbonate), ω-hydroxyl heterotelechelic poly (D,L-lactide)s (PDLLAs) were prepared with good end-group fidelity by ring-opening polymerization (ROP) of D,L-lactide catalyzed by organo catalyst namely, N,N′ dimethyl amino pyridine (DMAP) in conjunction with a renewable, functional bio-based initiator namely glycerol 1,2-carbonate (GC) in bulk at 135 °C with 82% yield. In the case of GC/DMAP catalyzed polymerizations, the HO-PDLLA-COOH series was not observed in MALDI TOF mass analysis unlike as obtained due to transesterification reactions when catalyzed by GC/Sn(Oct)₂. Also, cyclic carbonate end-functional 4-arm star poly(ε-caprolactone) (PCL) was prepared via coupling of GC with (PCL-COOH)₄ at room temperature in the presence of N,N′-dicyclohexylcarbodiimide (DCC) and DMAP. Quantitative conversion of hydroxyl functionality in (PCL-OH)₄ to carboxylic acid and then to cyclic carbonate functionality was achieved with 90% yield for low molecular weight 4-arm star PCL confirmed by NMR, FT-IR, and MALDI TOF mass spectroscopy.

Anion Exchange Membrane Reinforced with Polyethylene Substrate for Alkaline Fuel Cell Applications

To enhance mechanical robustness of our in-house anion exchange membrane (QPAF-4), the reinforcement technique was applied using ozone-treated, porous polyethylene (PE) thin film (Toray SETELA) as a substrate. Homogenous and flexible reinforced membranes (QPAF-4-PE, 15–20 µm thick) were obtained by bar-coating method. The cross-sectional SEM image and EDS analysis revealed triple-layered (sandwich-like) structure without detectable pinholes. The QPAF-4-PE with ion exchange capacity (IEC) of 1.48 meq·g⁻¹ exhibited lower water uptake (15 wt% at 90% relative humidity) and slightly lower hydroxide ion conductivity (71 mS·cm⁻¹ at 80 ℃) than those of the pristine QPAF-4 (IEC = 1.84 meq·g⁻¹, 25 wt% water uptake and 82 mS·cm⁻¹ of the conductivity). The reinforced QPAF-4-PE exhibited slightly higher viscoelasticity (particularly, in MD direction) due to the suppressed water absorbability. Furthermore, the elongation at break increased by 9.8% in TD direction and 6.3% in MD direction. An H₂/O₂ fuel cell using QPAF-4-PE as membrane was investigated at different back-pressure, in which the cell with 100 kPa back-pressure onto the cathode side only achieved the maximum performance (176 mW·cm−2 at current density of 364 mA·cm⁻²) and the longest durability for (>200 h) at a constant current density of 100 mA·cm⁻² maintaining 0.43 V of the cell voltage (67% remaining). The durability was eight times longer than that with ambient pressure and two times longer than that with back-pressure on both sides.

Green Composites Using Naturally Occurring Fibers: A Comprehensive Review

Depletion of non-renewable resources and health hazards of petroleum-based polymers and plastics has enforced the development of eco-friendly materials. The use of conventional plastics has to be minimized and can be replaced with environmentally friendly and sustainable bio-based polymers or biopolymers due to extensive environmental impact. A major share of petroleum-based polymers is used for polymeric composites with research focus on green composites and biocomposites containing renewable/bioderived matrix polymer and fillers from naturally occurring fibers. Biocomposites hold great promise to replace petroleum-based polymer composites owing to their lower cost, non-toxicity, abundance of raw material, renewability, and high specific strength. All these merits of biocomposites have led to an increment in the development of new biocomposites with enhanced properties, wide applicability and ever demanding criteria. The recently published review studies detailed the raw materials used, fabrication techniques, characterization, and applications including biodegradation and rheological studies performed in recent years. This review covers all the important properties of biocomposites along with detailed description of synthesis, properties, characterizations and applicability of these green composites in several areas. The review also focuses on their raw materials, types, recent biocomposites, processing techniques, characterizations, applications, and current challenges with future aspects.

Recent Progress in Modification and Preparations of the Promising Biodegradable Plastics: Polylactide and Poly(butylene adipate-co-terephthalate)

The acquisition of high-performance biodegradable plastics is of great significance in addressing the problem of environmental pollution of plastics. Polylactide (PLA) and poly(butylene adipate-co-terephthalate) (PBAT) are the most promising biodegradable polymers and have excellent functional properties. However, low elongation at break and impact strength of PLA and low tensile modulus and flexural strength of PBAT hinder their application. A large number of studies focus on improving the performance of PLA and PBAT and broadening their applications. In terms of polymer modification, this paper summarized recent progresses in both chemical and physical modification methods for PLA and PBAT, respectively. The properties of PLA can be improved by co-polymerization, grafting, cross-linking and blending. The properties of PBAT can be improved mainly through blending with other degradable polymers, natural macromolecules and inorganic materials. This review can provide the reference and ideas for the modification of biomass-based biodegradable plastics like PLA and fossil-based biodegradable plastics like PBAT.

Ultra-Thin Solid Electrolyte in Lithium-Ion Batteries

Safety concern of lithium-ion battery, attributed to using volatile and flammable liquid electrolytes, could be addressed by using solid electrolytes. Solid electrolytes including inorganic solid electrolytes, polymer solid electrolytes and organic/inorganic composite electrolytes have the common drawbacks in low ion-conductivity. Much efforts have been devoted to increase the specific ion conductivity, especially for inorganic solid electrolyte whose intrinsic conductivity is close to liquid electrolyte. However, most solid-state electrolyte membranes in lithium-ion batteries are thick, resulting in long ion-conduction pathway, low energy density and high cost. In this review, the advantages and disadvantages of different kinds of solid electrolytes were analyzed, and the promising strategies of ultra-thin solid electrolyte preparation were summarized and prospected. Applied organic-inorganic composite, continuous phase enhancement and in situ integration have been devoted to reducing thickness of electrolyte membrane and improving battery performance. On the basis of the technical requirement of lithium-ion batteries, this review aims to provide a guidance in terms of rational design and synthesis of ultra-thin solid electrolytes for the further research that addresses the safety issues and improves cycling performance of batteries.

Waterborne Polyurethane Dispersion Synthesized from CO₂ Based Poly (Ethylene Carbonate) Diol with High Performance

CO₂-based aliphatic polycarbonates (APCs) are not widely commercialized due to the poor performance and high cost, compared to the traditional synthetic materials. In this paper, poly(ethylene carbonate) diol (PECD) was synthesized from CO₂ and ethylene oxide (EO), and the comprehensive properties were characterized. Furthermore, the preparation and properties of waterborne polyurethane dispersion (WPU) derived from PECD were studied. The result showed that PECD had high reactivity, narrow molecular weight distribution index and excellent thermal stability. The obtained WPU exhibited superior tensile performance, adhesion properties and surface hardness. Due to the low cost of EO and CO₂, PECD is expected to be widely used in the preparation of polyurethanes.

Metal-Free Lewis Pair Catalysts for a One-Pot Terpolymerization of Propylene Oxide, ʟ-Lactide and CO₂

Multiblock and di-/tri-block copolymers are successfully synthesized for the first time via the metal-free terpolymerization of propylene oxide (PO), ʟ-lactide (LA) and CO₂ in one-pot/one-step and one-pot/two-step protocols respectively. Firstly, triethyl borane (TEB) and bis(triphenylphosphine)iminium chloride (PPNCl) Lewis pair is employed in the ring-opening polymerization of LA, wherein the catalytic efficiency is significantly correlated to the TEB/PPNCl feed ratio. Next, a series of TEB/base pairs are selected to synthesize the PO/LA/CO₂ terpolymer (PPCLA) in one-pot/one-step strategy. In PPCLA synthesis, LA exhibits the fastest reaction rate but severe transesterification is almost unavoidable, resulting in low molecular weight products. In order to prepare high-molecular-weight terpolymers, a one-pot/two-step methodology has to be applied. By this method, the copolymerization of PO/CO₂ proceeds first to form poly(propylene carbonate) (PPC) macroinitiators, which triggers the polymerization of LA to polylactide (PLA), leading to PLA-PPC or PLA-PPC-PLA block copolymers. The synthesized PLA-PPC-PLA block copolymers display improved thermal stability compared with PPC.

Review on Multi-Functional Separator for Li-S Batteries

Because lithium-ion batteries cannot meet increasing demand for power density, lithium metal batteries are expected as the next generation of rechargeable batteries. As one of lithium metal batteries, lithium-sulfur (Li-S) batteries have attracted extensive attention because of their ultrahigh power density (2600 Wh kg⁻¹) and low cost of sulfur. In order to overcome problems of active material loss, volume expansion and dendritic growth of Li metal in Li-S batteries, researchers have adopted several methods such as adding electrolyte additives, electrode modification and separator modification. Among them, separator modification shows significant advantages in inhibiting the shuttle effect of lithium polysulfides. This paper reviews research progress of inhibiting the shuttle effect of Li-S batteries by the means of the separator modification in recent years, including direct design of new type of separator and physical/chemical modification of separator surface. Through extensive reading and summarizing of the research results of the separator modification of Li-S batteries, we give the possible development direction of Li-S batteries at the end of the paper.

Sustainable Polymer & Energy: A New Open-Access Journal to Share Your Research on Sustainable Polymer and Advanced Energy Materials

Research Progress on Electrolyte Additives for Sodium Ion Batteries

In view of the gradual depletion of lithium resources, sodium-ion batteries (SIBs) have emerged as a viable alternative to lithium-ion batteries (LIBs). This is primarily attributed to their comparable operational principles and abundant reserves of sodium resources. As an essential component of the secondary battery, the electrolyte is of paramount importance in the functioning of SIBs, and the electrode-electrolyte interface constructed by it affects the battery performance. Adding electrolyte additives in LIBs is a low-cost and efficient method that can enhance the performance of the electrolyte and the interface between the electrode and electrolyte. This method is also applicable to SIBs. Therefore, in this study, we provide a comprehensive overview of various electrolyte additives, including but not limited to carbonate additives, sulfur-containing additives, silicon-containing additives, phosphorus-containing additives and inorganic additives. We extensively analyze the impact of these additives on the electrode-electrolyte interface and the electrochemical performance of SIBs. The purpose of this review is to comprehensively evaluate the current status of electrolyte additives in SIBs, which serves as both a basic overview of the existing situation and a practical guide for selecting suitable additives for practical applications of SIBs.

Green Composites Using Naturally Occurring Fibers: A Comprehensive Review

Depletion of non-renewable resources and health hazards of petroleum-based polymers and plastics has enforced the development of eco-friendly materials. The use of conventional plastics has to be minimized and can be replaced with environmentally friendly and sustainable bio-based polymers or biopolymers due to extensive environmental impact. A major share of petroleum-based polymers is used for polymeric composites with research focus on green composites and biocomposites containing renewable/bioderived matrix polymer and fillers from naturally occurring fibers. Biocomposites hold great promise to replace petroleum-based polymer composites owing to their lower cost, non-toxicity, abundance of raw material, renewability, and high specific strength. All these merits of biocomposites have led to an increment in the development of new biocomposites with enhanced properties, wide applicability and ever demanding criteria. The recently published review studies detailed the raw materials used, fabrication techniques, characterization, and applications including biodegradation and rheological studies performed in recent years. This review covers all the important properties of biocomposites along with detailed description of synthesis, properties, characterizations and applicability of these green composites in several areas. The review also focuses on their raw materials, types, recent biocomposites, processing techniques, characterizations, applications, and current challenges with future aspects.utf-8

Metal-Free Lewis Pair Catalysts for a One-Pot Terpolymerization of Propylene Oxide, ʟ-Lactide and CO₂

Multiblock and di-/tri-block copolymers are successfully synthesized for the first time via the metal-free terpolymerization of propylene oxide (PO), ʟ-lactide (LA) and CO₂ in one-pot/one-step and one-pot/two-step protocols respectively. Firstly, triethyl borane (TEB) and bis(triphenylphosphine)iminium chloride (PPNCl) Lewis pair is employed in the ring-opening polymerization of LA, wherein the catalytic efficiency is significantly correlated to the TEB/PPNCl feed ratio. Next, a series of TEB/base pairs are selected to synthesize the PO/LA/CO₂ terpolymer (PPCLA) in one-pot/one-step strategy. In PPCLA synthesis, LA exhibits the fastest reaction rate but severe transesterification is almost unavoidable, resulting in low molecular weight products. In order to prepare high-molecular-weight terpolymers, a one-pot/two-step methodology has to be applied. By this method, the copolymerization of PO/CO₂ proceeds first to form poly(propylene carbonate) (PPC) macroinitiators, which triggers the polymerization of LA to polylactide (PLA), leading to PLA-PPC or PLA-PPC-PLA block copolymers. The synthesized PLA-PPC-PLA block copolymers display improved thermal stability compared with PPC.utf-8

Review on Multi-Functional Separator for Li-S Batteries

Because lithium-ion batteries cannot meet increasing demand for power density, lithium metal batteries are expected as the next generation of rechargeable batteries. As one of lithium metal batteries, lithium-sulfur (Li-S) batteries have attracted extensive attention because of their ultrahigh power density (2600 Wh kg⁻¹) and low cost of sulfur. In order to overcome problems of active material loss, volume expansion and dendritic growth of Li metal in Li-S batteries, researchers have adopted several methods such as adding electrolyte additives, electrode modification and separator modification. Among them, separator modification shows significant advantages in inhibiting the shuttle effect of lithium polysulfides. This paper reviews research progress of inhibiting the shuttle effect of Li-S batteries by the means of the separator modification in recent years, including direct design of new type of separator and physical/chemical modification of separator surface. Through extensive reading and summarizing of the research results of the separator modification of Li-S batteries, we give the possible development direction of Li-S batteries at the end of the paper.utf-8

Green Synthesis of Gold Nanoparticles for Catalytic Reduction of 4-Nitrophenol and Methylene Blue for Sustainable Development

Unique structural features and wide applications of gold nanoparticles (GNPs) are inspiring researchers to develop biocompatible, reliable and cost-effective methods for their synthesis. Herein, a clean, eco-friendly and non-toxic method to obtain GNPs was developed by reducing and capping the liquid extract of stem of Lilium longiflorum and highlights the catalytic reduction of 4-nitrophenol (4-NP) and methylene blue (MB). The formation of GNPs was confirmed through the absorption peak at 535 nm in the UV-Vis spectra. TEM and HRTEM analyses reveal GNPs spherical morphology with an average size of 4.97 nm. SEM and EDX analyses further elucidate the spherical nature of GNPs and elemental composition. FTIR spectroscopy analysis demonstrates that the GNPs were coated with organic compounds, which prevent the nanoparticle from aggregation. GNPs exhibit remarkable efficiency in reducing 4-NP and MB. The catalytic efficacy of the synthesized GNPs was demonstrated through the enhanced reduction rates of 4-NP and MB, with rate constants of 1.50 min⁻¹ and 1.29 min⁻¹, respectively. This study develops a novel and eco-friendly technique for the synthesis of gold nanoparticles and opens possibilities for the green synthesis of other metal nanoparticles. The confirmed catalytic activity holds promise for a range of industrial applications and environmental sustainability. utf-8

Biobased Vitrimers: A Sustainable Future

Vitrimers are crosslinked polymers containing dynamic covalent linkages. Because of their crosslinked structure, they are stable as thermosets at their service temperatures. At high enough temperatures, dynamic exchange reactions occur and rearrange the polymer network, thus vitrimers become malleable and reprocessable like thermoplastics. The dynamic covalent bonds can also undergo dissociative cleavage reactions under specific conditions, so vitrimers are inherently degradable. To achieve a sustainable future, various biomass resources have been used as raw materials in vitrimer preparation. This review summarizes recent developments in biobased vitrimers and highlights their preparation methods. The limitations of current biobased vitrimers are also discussed.utf-8

Ultra-Thin Solid Electrolyte in Lithium-Ion Batteries

Safety concern of lithium-ion battery, attributed to using volatile and flammable liquid electrolytes, could be addressed by using solid electrolytes. Solid electrolytes including inorganic solid electrolytes, polymer solid electrolytes and organic/inorganic composite electrolytes have the common drawbacks in low ion-conductivity. Much efforts have been devoted to increase the specific ion conductivity, especially for inorganic solid electrolyte whose intrinsic conductivity is close to liquid electrolyte. However, most solid-state electrolyte membranes in lithium-ion batteries are thick, resulting in long ion-conduction pathway, low energy density and high cost. In this review, the advantages and disadvantages of different kinds of solid electrolytes were analyzed, and the promising strategies of ultra-thin solid electrolyte preparation were summarized and prospected. Applied organic-inorganic composite, continuous phase enhancement and in situ integration have been devoted to reducing thickness of electrolyte membrane and improving battery performance. On the basis of the technical requirement of lithium-ion batteries, this review aims to provide a guidance in terms of rational design and synthesis of ultra-thin solid electrolytes for the further research that addresses the safety issues and improves cycling performance of batteries.utf-8

Waterborne Polyurethane Dispersion Synthesized from CO₂ Based Poly (Ethylene Carbonate) Diol with High Performance

CO₂-based aliphatic polycarbonates (APCs) are not widely commercialized due to the poor performance and high cost, compared to the traditional synthetic materials. In this paper, poly(ethylene carbonate) diol (PECD) was synthesized from CO₂ and ethylene oxide (EO), and the comprehensive properties were characterized. Furthermore, the preparation and properties of waterborne polyurethane dispersion (WPU) derived from PECD were studied. The result showed that PECD had high reactivity, narrow molecular weight distribution index and excellent thermal stability. The obtained WPU exhibited superior tensile performance, adhesion properties and surface hardness. Due to the low cost of EO and CO₂, PECD is expected to be widely used in the preparation of polyurethanes.utf-8

Recent Progress in Modification and Preparations of the Promising Biodegradable Plastics: Polylactide and Poly(butylene adipate-co-terephthalate)

The acquisition of high-performance biodegradable plastics is of great significance in addressing the problem of environmental pollution of plastics. Polylactide (PLA) and poly(butylene adipate-co-terephthalate) (PBAT) are the most promising biodegradable polymers and have excellent functional properties. However, low elongation at break and impact strength of PLA and low tensile modulus and flexural strength of PBAT hinder their application. A large number of studies focus on improving the performance of PLA and PBAT and broadening their applications. In terms of polymer modification, this paper summarized recent progresses in both chemical and physical modification methods for PLA and PBAT, respectively. The properties of PLA can be improved by co-polymerization, grafting, cross-linking and blending. The properties of PBAT can be improved mainly through blending with other degradable polymers, natural macromolecules and inorganic materials. This review can provide the reference and ideas for the modification of biomass-based biodegradable plastics like PLA and fossil-based biodegradable plastics like PBAT.utf-8

Development of Eco-Friendly Composites Using Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and Diss Fibers (Ampelodesmos Mauritanicus)

In response to the growing environmental threats and pollution linked to synthetic plastics, current scientific inquiry is prioritizing the advancement of biodegradable materials. In this context, this study investigates the possibility of developing fully biodegradable materials using plant fibers extracted from the Diss plant (Ampelodesmos mauritanicus) as reinforcement in poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV)-based biocomposites. The biocomposites were prepared by melt blending in the following weight ratio: PHBV/Diss fibers 80/20. The chemical structure of Diss fibers was characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray fluorescence spectrometry (XRF). The impact of Diss fibers on the mechanical properties of biocomposites has also been investigated in comparison to neat PHBV. FTIR and XRF analyses identified cellulose, hemicellulose, and lignin as the main components of Diss fibers. On the other hand, the results showed a significant enhancement of Young’s modulus (⁓21%) of PHBV/DF biocomposites in comparison to neat PHBV due to a better dispersion of the fibers in the matrix, as confirmed by atomic force microscopy (AFM) images.utf-8

Biodegradable Composite Materials Based on Cassava Starch and Reinforced with Topinambur (Helianthus tuberosus) Aerial Part Fiber

The cultivation of topinambur (Helianthus tuberosus) has aroused the interest of producers since it is a source of inulin and can be used for biofuel production. During tuber processing, the aerial part of the crop remains as a by-product with no practical application. This work aimed to characterize the fibers obtained from the aerial part of topinambur and to evaluate their reinforcing potential in cassava starch-based films. Starch-based films with topinambur fiber (0, 5, and 10%) were prepared by extrusion followed by thermocompression. Topinambur residue contains 88.6% of total fiber, 8.5% ash, and 0.68% lipid. Mechanical film properties evidenced the reinforcement action of topinambur fiber, 10% content was able to increase up to 70% the Young’s modulus. SEM micrographs evidenced the good fiber-matrix interaction. UV-visible capacity, opacity, and chromaticity parameters of TPS films increased with fiber content in the formulation. Fiber incorporation improved the hydrophobicity of the biocomposite materials by increasing the contact angle. Starch-based films biodegraded more than 55% after 110 days, showing a similar trend to that of microcrystalline cellulose. Thus, topinambur residue can be effectively used as a reinforcing agent for TPS materials, being an innovative and non-toxic additive within the circular economy premises.utf-8