最新刊期
卷 53 ， 期 9 ， 2022
- 摘要：For a sustainable development of polymeric materials, it is not only necessary to seek sustainable source of raw materials for their production, but also need reducing environmental pollution and resource depletion after their discard. The recovery of waste polymeric materials is one of most effective approaches for addressing the above issues. Therefore, there is an increasing research interest focused on their effective recovery. According to different recovery objectives, the recovery of polymeric materials is divided into energy recovery, mostly carried out by incineration, and matter recovery, which is further divided into "physcycling" or "mechcycling" (physical or mechanical recovery), "chemcycling" (chemical recovery), "physchemcycling" or "mechchemcycling" (physical and chemical recovery), and "biologcycling" (biological recovery). In recent years, more attention have been paid to the quality, performance, or value (including economic/environmental value) of the recycled products, which are used to define the "downcycling" and "upcycling". Whenever possible, a closed-loop recovery (i.e. "recycling") is always desirable because it can produce the recycled polymers from waste polymeric materials via physical recycling and chemical recycling, respectively. However, both methods have their limitations. The recycled polymers via physical recycling almost inevitably have deteriorated performances compared with the original polymers, often manifesting itself as downcycling of polymeric materials. On the other hand, chemical recycling can offer an opportunity to revert waste polymeric materials back to their monomers for repolymerization to virgin materials without altering the properties of the material or the economic value of the polymers. Unfortunately, only a small subset of polymeric materials could be chemically recycled in an energy-efficient and cost-effective manner. Therefore, more and more efforts have been devoted to upcycling polymeric materials although this field is still in its infancy. Chemcycling with flexible ways and strong designability is regarded as a promising method for upcycling that can recovers added-value chemicals or materials from polymeric materials. However, the traditional degradation process of polymeric materials is always carried out under harsh conditions, and inevitably generates complex distribution of degraded products which are difficult to separate and reutilize. Selective degradation of polymeric materials using highly efficient catalysts provides a sustainable approach to addressing this challenge. Moreover, the chemcycling process can be largely affected by the aggregated structure and composition of polymeric materials. We choose typical thermoplastic, thermosetting and hybrid polymeric materials, which are widely used and of a large quantity, to discuss their chemical upcycling, especially present author's recent relevant research work, and provide an insight into the future development of chemical upcycling.关键词：Chemical recovery;Upcycling;Thermoplastic;Thermoset;Hybrid polymeric materials
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发布时间：2024-10-08 - 摘要：Developing chemically recyclable polymers represents a greener alternative to landfill and incineration and offers a closed-loop strategy toward a circular materials economy. Although some progress has been achieved in the synthesis of closed-loop recycled polymers, the synthesis of chemically recyclable polymers is still plagued with certain fundamental limitations, including trade-offs between the monomer's cyclizability and polymerizability, as well as between polymer's depolymerizability and properties. Very recently, our research group has proposed that amino acid-based dithiolactone monomers is a kind of "ideal monomer" for chemically recyclable polymers. These dithiolactone monomers demonstrate appealing chemical properties different from those of dilactone, including accelerated ring closure, augmented kinetics polymerizability, high depolymerizability and selectivity, and thus constitute a unique class of polythioester materials exhibiting controlled molecular weight (up to 100.5 kDa), atactic yet high crystallinity, structurally diversity, and chemical recyclability. In particular, the ring-opening polymerization of isopropyl dithiolactone derived from valine, delivered atactic yet crystalline polythioester. These amino acid-based chemically recyclable plastics show promise as next-generation sustainable materials.关键词：Chemically recyclable polymers;Amino acids;Dithiolactone;Polythioesters;Ring-opening polymerization
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发布时间：2024-10-08 - 摘要：The first industrial revolution of polymer materials, which ended in the 1970s, created the polymer world. The ongoing second industrial revolution may bring the polymer material industry into the "circular economy" mode, which is a rare opportunity for China's polymer science and industry to achieve leap-forward development. This article summarized the research progress of our team in the chemical and physical recycling of waste polymer materials, including high-temperature pyrolysis of waste polymer materials to olefins, straw and other waste biomass pyrolysis to hydrogen-rich synthesis gas, upcycling of carbon fiber reinforced composite, and a new method of high-temperature solid-state polymer grafting. The advantageous application fields and development prospects were also discussed. Finally, a new polymer "circular economy" development model was proposed. In the model, waste polymer materials and waste plastic oil will become feedstock for ethylene industry. The products obtained by cracking the feedstock can be separated into different chemicals, among which, ethylene, propylene etc. can be polymerized into brand-new polymers by existing petrochemical technology and equipment. Meanwhile, biomass materials, such as plant oil and straw, can be supplementary to this circular process as feedstock. This new model can not only help the polymer industry get rid of the reliance on fossil materials, but also solve both the "white" and "green" problems of polymers at the same time.关键词：Waste polymer materials;Recycling;Microwave;Plasma;High temperature solid phase grafting
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发布时间：2024-10-08 - 摘要：The synthesis of environment-friendly polymer materials, including polycarbonates and polyesters, supports the strategy of sustainable development, and it is also one of the feasible ways to solve the current environmental stress (greenhouse effect and white pollution, etc.). Carbon dioxide (CO2) has a wide range of sources and is non-toxic, but it could cause the greenhouse effect. Therefore, developing efficient techniques to transform CO2 into value-added chemicals is a promising solution for our sustainable society. CO2-based polycarbonate materials can be prepared by ring-opening alternating copolymerization (ROCOP) of CO2 and epoxide, while polyester materials can be prepared by ROCOP of epoxide and anhydride. Organocatalysts, as a type of emerging "metal-free" catalysts, have developed rapidly in the past 20 years and exhibited unique properties and exceptional promises for various polymerization reactions. Recently, our group have developed a series of organic phosphazenes, which are a family of extremely strong, non-nucleophilic, and uncharged auxiliary bases and show remarkable potential as organocatalysts for ring-opening polymerization (ROP) of cyclic monomers. On the other hand, phosphazenes in combination with a Lewis acid, such as triethyleborane (TEB), can easily construct diverse binary organocatalysts that exhibite excellent catalytic performances. Apparently, organocatalytic synthesis of polymer materials has become an important and hot research topic. This feature article reviews the recent progress in the field of ROCOP of CO2/epoxide/anhydride catalysed by organocatalysts followed by a proper discussion of respective polymerization mechanisms. The review includes three sub-topics, i.e., ROCOP of CO2/epoxide, ROCOP of epoxide/anhydride, and terpolymerization of CO2/epoxide/anhydride. A short perspective viewpoint is provided at the end for readers who are interested in this area.关键词：Organocatalyst;Ring-opening polymerization;Alternating copolymerization;Polycarbonate;Polyeste
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发布时间：2024-10-08
Feature Article
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Research Progress on Ring-opening Polymerization Catalysts and the Synthesis of Aliphatic Polyesters
摘要：Compared with widely used polyolefin materials, aliphatic polyesters can show the same properties, and their unique biocompatibility and degradability make them widely used in electronics, absorbable surgical suture, food packaging, biomedicine and so on. They have become an environmentally friendly substitute for traditional polyolefin plastics, especially aliphatic polyester materials derived from biomass. Ring opening polymerization (ROP) is the main method for synthesizing aliphatic polyester at present. Aiming at the application of catalytic ring opening polymerization in the synthesis of aliphatic polyester, this paper summarizes two main catalytic systems involved in this field, namely metal based catalyst and metal free organic catalyst, and gives a preliminary introduction to the emerging enzyme catalytic system. This paper lists the chemical structures of relevant important catalytic systems, aims to reveal the catalytic reaction characteristics of various systems, and focuses on and comments on the effects of catalyst structure on catalytic efficiency, controllability, molecular weight and stereoselectivity. Specifically, metal based catalysts mainly include complexes formed by the coordination of central metal with N-heterocyclic carbene and thiourea, which have great adjustability in structure, and different structures can be selected according to the needs of catalysis; Metal free organic catalysts such as organic base catalysts (phosphonitrile base, N-heterocyclic carbene, etc.) and organic acid catalysts (phosphoric acid, squaric acid, etc.) often have the advantages of high catalytic efficiency, molar mass control and stereoselectivity. In addition, lipase catalyst has the characteristics of wide reaction range, mild reaction and no metal pollution residue.关键词：Ring-opening polymerization;Aliphatic polyester;Metal-Based Catalysts;Organocatalysts- 754
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发布时间：2024-10-08 - 摘要：Natural cellulose cannot be melted and is difficult to process due to its strong hydrogen bonding network. Thermoplastic processing of cellulose is achieved only under harsh processing conditions or with the addition of large amounts of plasticizers, but the resulting material suffers from numerous drawbacks. So the internal plasticization method of introducing new derivatized groups has received extensive attention, but the internal plasticization method will lead to a significant decrease in the degradation performance of cellulose materials. How to prepare cellulosic materials with both thermoplasticity and degradability remains a challenge. This paper summarizes the relevant progress in the field of thermoplastic processing of cellulose materials, promoting the construction of materials with both thermoplasticity and degradability to solve the environmental hazards of thin and light materials such as heat-sealing coatings and films.关键词：Cellulose;Thermoplastic processing;Cellulose derivatives;Plasticizer;Derivatization
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发布时间：2024-10-08
Review
- 摘要：Endowing epoxy resin derived from bio-based glycidyl ester with controllable degradation in mild condition and high-valued recovery is a huge challenge. We design a novel cross-linked network with the degradable spior acetal structure orderly distributed on branch chains through the curing reaction between camphoric acid-based diglycidyl ester and vanillin-based amine curing agent. To investigate degradation mechanism of the epoxy resins, the degradation behaviors in 0.1 mol/L H+ acidic aqueous solutions for 48 h at 50 ℃ were monitored by the degradation kinetics and real-time 1H-NMR spectra. The result indicated that the cross-linked network with spiro acetal structure was hydrolyzed into pentaerythritol and oligomers, and then camphoric acid was obtained by the hydrolyzation of ester bonds in oligomers. The degradation products in different periods were extracted by water to recover the raw material monomer (yield, pentaerythritol >85.5%, camphoric acid >58.9%), which realized the controllable degradation and chemical recovery of epoxy resin by a green method. The curing agent formulation of the epoxy resin was adjusted to enhance thermal stability and tensile properties of resin samples, and samples with NVP performed excellent antimicrobial property (ratio, >95%) for both E. coli and S. aureus bacteria because of β-amino alcohols generated in the curing reaction. The above result will inspire more synthesis of epoxy resin with controllable degradation, chemical recovery and antimicrobial property.关键词：Epoxy resin;Diglycidyl ester;Controllable degradation;Chemical recovery;Antimicrobial property
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发布时间：2024-10-08 - 摘要：Polycarbonate is one of the most important polymeric materials in human society, which has found wide application in various areas owning to its excellent properties. However, traditional polycarbonates are derived from non-renewable petroleum-based chemicals, some of which are highly toxic. Therefore, the search for renewable resources, such as biomass and carbon dioxide, to replace petroleum-based chemicals for polymer synthesis has received great attention in recent years. In this work, thioether-containing bisphenols were synthesized from bio-based eugenol and dithiols with different lengths of carbon chain via thiol-ene click reaction initiated by UV light. The structures of eugenol-based bisphenols were confirmed by 1H- nuclear magnetic resonance (1H-NMR), 13C- nuclear magnetic resonance (13C-NMR) and Fourier-transform infrared spectroscopy (FTIR), and the yield reached 76.2%. The obtained bisphenols were polymerized with triphosgene under mild conditions to prepare eugenol-based poly(thioether carbonate)s with satisfying yields. The structures of eugenol-based poly(thioether carbonate)s were illustrated by 1H-NMR, 13C-NMR and FTIR, which demonstrated the successful preparation of poly(thioether carbonate)s. Gel permeation chromatography (GPC) analysis revealed that the molecular weight of those eugenol-based poly(thioether carbonate)s was in the range from 3.27×104 g/mol to 5.72×104 g/mol with polydispersity index between 1.1 and 1.9. The results of the thermal gravimetric analysis revealed that all the eugenol-based poly(thioether carbonate)s exhibited a one-step degradation pattern with a weight loss of 5% in the range of 343-359 ℃, and maximum degradation rates were found between 379 and 395 ℃, indicating the good thermostability of the as-prepared eugenol-based poly(thioether carbonate)s. The glass transition temperature of eugenol-based poly(thioether carbonate)s decreased from 24.4 ℃ to 12.2 ℃ as the lengths of the carbon chain of dithiols increased. Finally, one eugenol-based poly(thioether carbonate) was post-oxidized with m-chloroperbenzoic acid to obtain poly(sulfone carbonate), which was confirmed by 1H-NMR, 13C-NMR and FTIR. After post-oxidation, the obtained poly(sulfone carbonate) exhibited decreased thermal stability and glass transformation temperature.关键词：Eugenol;Polycarbonate;Thiol-ene Click Reaction;Post-oxidation
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发布时间：2024-10-08 - 摘要：图文摘要:;Isobutene oxide (IBO) is a derivative of isobutene that is an important C4 product in petrochemical industry. The preparation of aliphatic polycarbonates by the copolymerization of IBO with carbon dioxide (CO2) is a feasible way to utilize isobutene and CO2 with high added value, but only few studies have been reported so far. In this paper, heterogeneous Zn-Co bimetal cyanidation complex (Zn-Co DMCC) was used to catalyze the copolymerization of IBO with CO2 at 40 ℃, and the catalytic efficiency was up to 1.6 kg copolymer/g DMCC. The product of poly(butyl carbonate) (PIBC) had a fully alternating structure and a regional regularity of 95%. The number-average molecular weight was up to 18.6 kDa, and the lowest content of cyclic by-product was 7 mol%. PIBC is a crystalline polymer with a melting point of 93.7 ℃, but the crystallization rate of PIBC is slow. The initial thermal decomposition temperature of PIBC is only 145 ℃. The tensile strength of PIBC is 4.4 MPa and the elongation at break is 350%. Therefore, PIBC may be used in sacrificial adhesives. DMCC also catalyzed the copolymerization of CO2, IBO and maleic anhydride (MA) to obtain a fully alternating terpolymer. The results provide a new sustainable development path for the application of isobutene.关键词：Carbon dioxide;Polycarbonate;Isobutene oxide;Maleic anhydride;Crystalline polymer
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发布时间：2024-10-08 - 摘要：To alleviate the energy and environment pressures resulted from the consumption of petroleum-based polymers, it is of great significance to synthesize the bio-based polyesters with degradability, sustainability and environmental friendliness. Various types of polymerization methods have been developed to accomplish such synthesis. Here it is shown that Lewis pair composed of N-heterocyclic olefin (NHO) and organic boron to synergistically catalyze the alternating copolymerization of 3,4-dihydrocoumarin (DHC) and epoxide by Lewis pair polymerization (LPP) for the first time. The effects of the substituents of Lewis acids (LA) and Lewis bases (LB) on the catalytic activity, chemoselectivity of alternating copolymerization versus homopolymerization of epoxides, regioselectivity of epoxides have been systematically studied. It turned out that the weaker acidity of BEt3 is beneficial for the alternating copolymerization activity relative to BPh3 and B(C6F5)3. After heating at 80-100 °C, such LPP system can achieve 52%-97% conversion of DHC in 12 h, 89%-100% polyester selectivity and 93%-97% regioselectivity. In combination with the experimental details including the identification of active species and mono-initiator, MALDI-TOF MS analysis of low molecular weight polyesters, and NMR reactions, the influences of exocyclic double bond of NHO with varying methyl substitution on polymerization mechanism were studied thoroughly. It turned out that NHO1 with two methyl groups substituted at the exocyclic double bond initiates the polymerization via alkaline, whereas NHO2 with one methyl group substituted at the exocyclic double bond initiates the polymerization via nucleophilicity. It is noted that the NHO2-DHC/TEB LP exhibit a unique, asymmetric dual initiation capability of synthesizing linear polyesters. Due to the complete inhibition of intramolecular transesterification by NHO2-DHC/TEB LP, there is no formation of cyclic polyester by-products, thus realizing the controllable synthesis of dual-initiated linear polyesters. This strategy provides important experimental and theoretic foundation to the rapid synthesis of DHC related polyester-based triblock polymers, thermoplastic elastomers and etc.关键词：Lewis pair;Alternating copolymerization;Bio-based polyester
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发布时间：2024-10-08 - 摘要：A hydroxyproline-derived bridged bicyclic lactone monomer (NnHex-HPL) was prepared and copolymerized with the commercially available ε-caprolactone (CL) and δ-valerolactone (VL). In a one pot fashion, NnHex-HPL was fed as the hard segment after the complete conversion of CL and VL in the polymerization, to generate a series of ABA triblock copolyesters BP1-3. The composition and physical properties of BP1-3 can be facilely tuned by adjusting the content and ratio of NnHex-HPL. BP1-3 can be processed with hot pressing to obtain transparent films and samples with characteristic properties of thermoplastic elastomer. The material has a melting point nearly 200 ℃, which corresponds to a higher upper limiting temperature in its applications. Mechanical tests, mainly uniaxial tensile tests, show the material can obtain Young's modulus over 20 MPa and toughness as high as 100 MJ·m-3, which are comparable to most reported thermoplastic elastomer polyesters.关键词：Hydroxyproline;Thermoplastic elastomer;Block copolymer;Polyester
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发布时间：2024-10-08 - 摘要：图文摘要:;As one of the chemical recycling to monomer polymer, poly(γ-butyrolactone) (PBL), polymerized from intrinsically recyclable five-membered γ-butyrolactone ring, exhibits unique properties and complete recyclability. Therefore, it receives more and more attention in polymer science. In order to accurately understand the effect of structures of PBL on crystalline behaviors, a series of discrete oligo(γ-butyrolactone)s (oBLs) with different chain lengths were synthesized via iterative exponential growth strategy combined with efficient esterification conditions using γ-butyrolactone and succinic anhydride as starting materials. The molecular structures of these discrete oBLs are validated by size-exclusion chromatography, matrix-assisted laser desorption ionization time-of-flight mass spectrometry and 1H-NMR spectroscopy. We systematically investigate the crystalline behaviors of oBLs using differential scanning calorimetry and polarized optical microscopy. Specifically, we focus our attention on the effect of molecular weight (MW) and molecular weight distribution on nucleation, crystallization temperature, melting temperature, crystal growth rate and crystallization rate of oBLs. The nucleation rate, crystallization temperature, melting temperature, crystal growth rate and crystallization rate increase with an increase of molecular weight of discrete oBLs. For dispersed PBL, the high-MW components dominate the crystallization behaviors. Dispersed PBL exhibits relatively high nucleation rate, crystal growth rate and crystallization rate compared to discrete oBL with similar molecular weight.关键词：Discrete polymer;Oligo(γ-butyrolactone);Iterative exponential growth;Crystalline behaviors
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发布时间：2024-10-08 - 摘要：图文摘要:;Poly(ethylene terephthalate) (PET) is one of the five general engineering plastics, with an annual consumption of nearly 70 million tons in the world. How to realize the sustainable development of PET has always been the focus of academic and industrial circles and an important trend in this field is to develop a new way of recycling PET. At present, the biological enzymatic regeneration of PET is still in the initial exploration stage, and there are some insurmountable problems such as low efficiency and poor selectivity. Therefore, the physical degradation or chemical conversion of PET is the most likely way to realize industrial regeneration. Generally, the chemical conversion method of PET is to depolymerize the main chain through alcoholysis reaction to form terephthalic acid (ester) and ethylene glycol monomer, and then a series of complex post-treatment processes such as purification, washing and rectification to make the monomer reach the polymerization level, and finally giving regenerated PET (r-PET) following esterification and polycondensation processes. However, this chemical conversion and regeneration method has a long process flow and high energy consumption. Herein, we propose a “one pot” strategy to recycle of PET by diol-initiated alcoholysis and the successive diacids-triggered esterification and polycondesation.The highlight of the strategy lies in the depolymerization and copolymerization reaction distribution of PET is carried out through the “one pot” method, so as to convert PET into biodegradable polymer materials. The “one pot” method not only eliminates the complex and high energy consumption process of purifying monomers, but also a 100% regeneration of PET recycled material is realized, which meets the basic requirements of sustainable development. It is worth pointing out that choosing different alcoholysis agents and dibasic acids for depolymerization, esterification and co-polycondensation can realize the regulation of the properties of regenerated polymer materials. The method of “depolymerization-polycondensation” to synthesize biodegradable polymers proposed in this paper has reference value for promoting the high-value recovery and regeneration of PET.关键词：Poly(ethylene terephthalate);Chemical Conversion;Depolymerization;Copolycondensation;Biodegradable Polymer
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发布时间：2024-10-08 - 摘要：Despite that γ-methyl-α-methylene-γ-butyrolactone (γ-MMBL) shows great potential in substituting the methyl methacrylate (MMA) for synthesizing the acrylic polymer with intriguing physical properties and enhanced depolymerization selectivity, the possibly industrial production of this cyclic monomer is unfortunately not practical due to low overall yields, harsh reaction conditions, and time-consuming multistep process. Here we report a convenient and effective synthetic approach to γ-MMBL via zinc-mediated allylation-lactonization one-pot reaction of acetaldehyde with ethyl 2-(bromomethyl)acrylate. Under simple room-temperature sonication conditions, quantitative conversions can be accomplished within 5 min, providing pure γ-MMBL with high isolated yields of 80%. This synthetic method can also be applied to efficient preparation of cuminaldehyde, 2-furaldehyde, lauraldehyde-derived methylene butyrolactones with high yields (80.4%‒83.5%). The development of Lewis pair catalyst based on methylaluminum bis(2,6-di-tert-butyl-4-methylphenoxide) (MeAl(BHT)2) or tris(2,4,6-trifluorophenyl)borane (B(2,4,6-F3C6H2)3) Lewis acid and 3-diisopropyl-4,5-dimethylimidazol-2-ylidene (IiPr) Lewis base enables their rapid polymerizations with a high degree of control, affording new poly(methylene butyrolactone)s with thermal properties tuned in a wide range. Through the utilization of a muffle furnace coupled with a cooling-trap, effective depolymerizations of these poly(methylene butyrolactone)s have been achieved with monomer recovery up to 98.8%, thus successfully constructing new acrylic polymers with closed-loop recyclability.关键词：Chemically recyclable polymer;Acrylic polymer;Controlled/Living polymerization;Lewis pair polymerization;Methylene butyrolactone
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发布时间：2024-10-08
Research Article
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