最新刊期
- 摘要：As high-water absorption and high-water retention polymers, hydrogels are widely used in many fields such as smart materials, water absorption materials, drug delivery, slow release, skin dressings, and biomedicine. However, the traditional hydrogels like polyacrylamide (PAAm) have the limitation of low mechanical strength and poor stability, which greatly limits the development of hydrogels. The commonly used methods to increase the strength of hydrogels include the construction of double-network structure hydrogels, the introduction of chemical groups to modify hydrogels, the introduction of nanoparticles to form nanocomposite hydrogels, and so on. In this work, the mechanical properties of PAAm hydrogels are mainly improved by introducing hydrophilic silica (SiO2) nanoparticles. The results show that SiO2 nanoparticles, as multi-functional crosslinking agents, are physically adsorbed or chemically bonded into the hydrogel matrix to enhance the 3D network structure of the hydrogel. In addition, hydrogen bonds formed between the silicon hydroxyl group on the surface of SiO2 nanoparticles and the amide group on the polymer chain, which increases the crosslinking density of the hydrogel and greatly improves the compression performance. The SiO2 nanoparticles are hydrophilic, which will increase the water absorption of the composite hydrogel and increase the swelling rate, but the swelling rate will decrease due to the limitation of the three-dimensional mesh of the hydrogel. The energy storage modulus of composite hydrogels will gradually increase due to the denser three-dimensional mesh structure, but the loss modulus will increase due to the increase of internal structure friction, but also because of the denser mesh, the increase of loss modulus will be limited. In general, the addition of SiO2 nanoparticles has a certain significance for improving the viscoelasticity of hydrogels.关键词：Acrylamide;SiO2 nanoparticles;Composite hydrogel;Viscoelasticity766|1|0更新时间：2025-03-07
-
Direct Solid State Polymerization and Structural Properties of High Heat Resistant Copolyamide PA56T
摘要：To address the issues of diamine volatilization, low yield, and difficulty in increasing molecular weight during the direct solid state polymerization (DSSP) of high-temperature-resistant polyamides, this study first used dimethyl terephthalate (DMT) to react with excess 1,5-pentanediamine (PDA) and 1,6-hexanediamine (HMDA) to prepare diamides diamines 5T5 and 6T6. Then, 5T5 and 6T6 were reacted with terephthalic acid (PTA) to form different compositions of 5T5T/6T6T mixed salts. Finally, a series of high-viscosity, high-temperature-resistant copolyamides PA56T were successfully synthesized through direct solid state polymerization from the mixed salts. The structure and properties of PA56T were systematically investigated using FTIR, NMR, DSC, and TGA. The results indicate that using diamides diamines as amide salts can effectively prevent the volatilization of diamines during the direct solid-state polymerization process, thereby significantly improving the yield, molecular weight, and quality of the high-temperature-resistant copolyamides. By changing the composition, the comprehensive properties of the copolyamide PA56T can be effectively regulated. Its melting point (Tm) first decreases and then increases with the increase in 6T content. Copolymerization enhances the thermal stability of the high-temperature-resistant polyamides. The copolymer PA56T-40, with 40 mol% 6T content exhibits excellent comprehensive properties, with a melting point (Tm) of 310 °C, a 5 wt% weight loss temperature (Td5) of 440 °C, and a tensile strength of 95.2 MPa.关键词：High heat resistant polyamide;Copolyamide;Diamide diamine;Direct solid state polymerization;Mechanical property564|0|0更新时间：2025-03-07 - 摘要：Thermoplastic polyurethane (TPU) has become a pivotal engineering material due to its unique combination of elasticity and processability. Recent research has focused on elucidating the structure-property relationship to guide high-performance TPU design. This study innovatively explores the impact of segment sequence length on material performance through a systematic synthesis strategy. Using pre-polymerization and chain extension techniques, we developed a series of hydrazide-based TPU elastomers with identical hard/soft segment ratios but varying sequence lengths. Characterization results reveal that extending the sequence lengths induces two critical structural modifications: enhanced microphase separation between hard and soft domains, and optimized hierarchical hydrogen bonding networks. These structural changes collectively elevate material performance, with long-sequence TPUs exhibiting a 50% increase in tensile strength (from 50 MPa to 80 MPa), and significantly higher flow temperatures (ΔT >45 °C) compared to short-sequence counterparts. Notably, stress relaxation tests demonstrate that extended sequences increase the relaxation time significantly, indicating superior dimensional stability. The performance enhancements stem from the dual reinforcement mechanism: microphase separation creates robust physical crosslinks while hierarchical hydrogen bonds enable energy dissipation. This sequence engineering approach provides a paradigm shift from traditional composition-focused design to topological structure optimization, offering a viable pathway for developing TPUs that simultaneously satisfy conflicting requirements of mechanical robustness and processing efficiency in industrial applications.关键词：Thermoplastic polyurethane;Elastomer;Sequence length;Hydrogen bond;Mechanical properties648|0|0更新时间：2025-03-07
- 摘要：Lewis bases are frequently employed as polar modifiers to enhance the 1,2-selectivity of butadiene anionic polymerization. In this work, we report four novel N,O-bidentate Lewis bases bearing different alkyl substituents: 1-(2-methoxyethyl)piperidine (MOD 1), 1-(2-ethoxyethyl)piperidine (MOD 2), 1-(2-propoxyethyl)piperidine (MOD 3), and 1-(2-butoxyethyl)piperidine (MOD 4). A comparative study was conducted between these newly synthesized polar modifiers and five commonly used, previously reported modifiers, focusing on their effects on the anionic polymerization of butadiene. Additionally, we investigated how the dosage of various modifiers and the polymerization temperature influence the polymerization behavior. The results show that the newly designed N,O-bidentate polar modifiers can achieve a high degree of 1,2-structural regulation in polybutadiene at relatively low dosage levels. Their regulatory effectiveness remains stable across different polymerization temperatures, demonstrating both high efficiency and excellent stability.关键词：Anionic polymerization;Polar modifiers;Butadiene;Microstructure424|0|0更新时间：2025-03-07
- 摘要：Cycloaddition of carbon dioxide (CO2) and epoxides can boast 100% atomic economy, and it is considered an up-and-coming method for CO2 utilization. However, the need for harsh reaction conditions presents a significant challenge. This study addresses this issue by successfully preparing the cellulose-supported ionic liquid as a porous catalyst (PPCIL) via the reaction of allyl cellulose ether (AHP-cellulose) and vinyl imidazolium bromide ([VPIM]Br). The catalytic activity of PPCIL was thoroughly investigated. It was found that end epoxides with small-sized substituents such as epichlorohydrin, epibromohydrin, and propylene oxide, can be completely converted to corresponding carbonates over PPCIL at 80 °C and 0.1 MPa. When the temperature rose to 100 °C, PPCIL also revealed good catalytic activity towards end epoxides with larger size such as allyl glycidyl ether and styrene oxide. PPCIL can effectively activate the CO2 and epoxy substrates, and potential reaction mechanisms were proposed. Notably, PPCIL demonstrated high catalytic activity even after being recycled for five times, maintaining a yield of 88.5% and a selectivity of 98%. In summary, this study offers an effective strategy for heterogenizing ionic liquids for catalytic activation CO2 to cyclic carbonates under mild conditions.关键词：CO2;Ionic liquids;Cellulose modification;Porous catalyst615|0|0更新时间：2025-03-03
- 摘要：Polymer-based fibrous filtration materials are widely used, however, the development of high-temperature filtration application using engineering thermoplastics are limited by the difficulty of wet spinning and fiber refinement. In this paper, a nanofibrous membrane was prepared by electrospinning using the high performance engineering polymer polyetherketoneketone (PEKK), which can be dissolved in trifluoroacetic acid. And the regulation laws of the fiber diameter and morphology were investigated, as well as its characteristics for high temperature filtration application. The study shows that: the average diameter of the fiber can be refined to 87 nm, the pore size of the fiber membrane can be reduced to 293 nm, and the tensile strength can reach 7.77 MPa; the fiber membrane shows excellent filtration performance with the filtration efficiency of higher than 99.9% at a thickness of 6 μm; the fiber membrane maintains a good morphological structure, force, thermal properties, and high-temperature air filtration properties at 300 °C.关键词：Polyetherketoneketone;Electrospinning;Nanofiber;high temperature589|0|0更新时间：2025-03-03
- 摘要：Polydicyclopentadiene (PDCPD) is flammable, its polymerization process is complicated and the period is long. In this paper, a flame retardant monomer NB-DOPO were designed and synthesized by introducing 9, 10-dihydro9-oxaze-10-phosphoxene-10-oxide (DOPO) into the norbornene. This monomer can be copolymerized with dicyclopentadiene (DCPD) by frontal ring-opening metathesis polymerization (FROMP) to prepare the PDCPD/NB-DOPO copolymers with intrinsic flame retardant properties. The effects of the introduction of NB-DOPO on the FROMP process and the dynamic mechanical properties, thermal stability, mechanical properties as well as the flame-retardant properties of the copolymers were studied. On that basis, the possible flame retardant mechanism of the PDCPD/NB-DOPO copolymer was explored further. The results indicated that NB-DOPO could copolymerize with DCPD randomly, and thus the frontal polymerization velocity of the copolymerization was reduced. According to this, a controllable FROMP was achieved while maintaining a high curing degree of the material. When the content of NB-DOPO was below 10%, the introduction of NB-DOPO with high ring tension promoted the formation of cross-linking points in the system, reduced the molecular weight of cross-linking points (Mc), and enhanced the storage modulus and mechanical properties of the copolymer; When the concentration of NB-DOPO reached 30%, the cross-linking density of PDCPD/NB-DOPO declined, the rigid structures in the NB-DOPO acted as physical cross-linking points, hence the mechanical properties of the material could be kept at a high level accompanied by a markedly enhanced flame retardancy, and the limiting oxygen index (LOI) of the material was increased by 38% in comparison to that of PDCPD, that material exhibited superior comprehensive properties.关键词：Polydicyclopentadiene;Frontal ring-opening metathesis polymerization;Intrinsic flame retardant;Random copolymerization;Crosslinking density575|0|0更新时间：2025-03-03
- 摘要：Covalent organic framework nanosheets (CONs) are a class of two-dimensional layered materials with exceptional properties. The inherent features of COF materials, such as pre-designable periodic structures, atomic-level precision, tunable functionality, excellent thermal stability, permanent porosity, and ultralow density, endow CONs with significant potential for further development. However, challenges such as low exfoliation efficiency of COF nanosheets and poor size controllability complicate membrane fabrication processes. In this study, a liquid-phase exfoliation method was employed to prepare pyridine-based COF nanosheets (TpBpy-CON) and assemble them into COF membranes (TpBpy-COM). COF powders were exfoliated under mild conditions to obtain size-controllable TpBpy-CON. The resulting COF nanosheets exhibited high aspect ratios, specific surface areas, and porosity. Subsequently, the nanosheets were assembled into COF membranes using vacuum-assisted techniques. The fabricated TpBpy-COM demonstrated a compact membrane surface structure and excellent H2/CO2 gas separation performance.关键词：Liquid-Phase Exfoliation;Covalent organic frameworks;Nanosheet Assembly;Gas Molecular Sieving823|0|0更新时间：2025-02-24
- 摘要：The self-healing properties of rubber products can be given by the introduction of dynamic crosslinking bonds. In this work, carboxylated cellulose nanocrystals (CCA) and zinc oxide (ZnO) were selected as fillers. Carboxylated styrene-butadiene rubber (XSBR) composites (X/C/Z) with dual dynamic crosslinking networks were constructed by constructing ionic bonds between Zn2+ of ZnO and the carboxyl groups of XSBR and CCA, as well as hydrogen bonds between the carboxyl groups of CCA and XSBR. The FTIR results confirmed the existence of dual dynamic crosslinking networks in X/C/Z composites. Compared with XSBR/CCA and XSBR/ZnO composites, the dual dynamic crosslinking networks and the synergistic reinforcement of CCA and ZnO endow X/C/Z composites with more excellent physical and mechanical properties. Fixed the CCA content at 5 wt%, the crosslinking density of X/C/Z composites increased with the increase of ZnO content. The tensile strength of the composites also showed an increasing trend, while the elongation at break gradually decreased. Meanwhile, the increase of ZnO content provided more Zn2+ that can complex with the carboxyl groups of XSBR and CCA to form ionic bonds. As a result, the self-healing ability of the composites were enhanced greatly. In this paper, using ZnO and CCA as reinforcing/cross-linking fillers, carboxylated styrene-butadiene rubber self-healing composites with excellent properties were prepared by a simple and convenient method, which provided a way for the development of self-healing composites.关键词：carboxylated cellulose nanocrystals;zinc oxide;carboxylated styrene-butadiene rubber;dynamic crosslinking;Self-healing647|0|0更新时间：2023-02-08
- 摘要：In recent years, immunotherapy, as a new therapeutic method, received extensive attention in the field of tumor therapy due to the exciting therapeutic effects on many types of malignant tumors. Though the development of immunotherapy is in full swing, immunotherapy still faces many challenges, such as low immune response rate, immune related adverse events. Using drug delivery materials for targeted delivery immune agents is an effective means to solve the current problems of immunodrugs and further improve the therapeutic index. Compared to chemotherapeutic agents, the target, mechanism and mode of action of immune agents are different, which poses a new challenge to the design of drug delivery materials. In this paper, we summarized the challenges in the process of immunodrugs delivery, and introduce the design ideas and representative results of polymeric materials for immune drug delivery to the tumor and lymph nodes. For the delivery of immune drug to tumor, we firstly showed 3 types of nanoparticles——polypeptide-dexamethasone conjugate, aspirin polymeric prodrug and nano-assembly of bile acid receptor modulators for releasing the immunosuppression in the tumor site. Then we introduced the polylactic acid block polyethyleneimine CpG loaded nanoparticles combination with oxaliplatin for inducing the immunogenic death and further enhancing the in-situ antitumor immunity. Finally, we present the strategy of hierarchical delivery of immune agents to tumors and lymph nodes using supramolecular assembled programmable nanomedicine. Furthermore, the influence of drug release mode on the immune stimulation effect was explored by the implants crosslinked by polyethylene glycol and polysaccharide. For the delivery of immune drug to lymph node, pathogen-mimicking polymeric nanoparticles were used for realizing the efficient reflux of antigen and adjuvant to lymph nodes, and polyethyleneimine derivatives with stimulator of interferon genes (STING) adjuvant function were synthesized for achieving the spatiotemporal synergy between activating antigen presenting cells and promoting antigen cross presentation. Finally, we forwarded the problems that need to be solved and the future research direction in the field of immunodrug delivery.关键词：Biomedical polymers;Drug delivery;Tumor therapy;Immunotherapy886|1|2更新时间：2023-01-06
- Postal code：100190
- Tel：010-62588927 Email：gfzxb@iccas.ac.cn
- Technical support is provided by Beijing Founder electronics co., LTD 京ICP备05002797号-8
京公网安备11010802046899号 - It is recommended to read the content of this site in Chrome&IE9+. Please switch to extreme mode in browser 360.
- Cookies We use cookies to help provide and enhance our service and tailor content. By continuing, you agree to the use of cookies.
0