最新刊期
      卷 55 ， 期 4 ， 2024

        Review

      • Wen-tao Zhai,Jun-jie Jiang
        Vol. 55, Issue 4, Pages: 369-395(2024) DOI: 10.11777/j.issn1000-3304.2023.23252
        摘要：The viscoelasticity of a supercritical fluid batch foaming system is easily controllable, and its processing parameters and equipment are also readily adjustable, making it the most favored technical pathway in the physical foaming of thermoplastic elastomers. This review introduces the literature, research and development history, as well as the current application status of thermoplastic elastomer foams. Firstly, the review clarifies the basic concepts, technical characteristics, and interaction between thermoplastic elastomer and supercritical fluid. It also discusses the characteristics of "high-elastic foaming" during batch foaming of thermoplastic elastomer, as well as the mechanisms of cell nucleation, growth, and structure shaping, along with regulatory strategies for foam shrinkage in high-elastic state. Secondly, this review examines the preparation methodology for preparing foamed films made from thermoplastic elastomers, the steam-chest molding process applied to thermoplastic elastomer foamed beads, and the strength of the interface between the beads, as well as the mechanism of inter-bead bonding. Additionally, the elastic properties of foam materials made of thermoplastic elastomers based on the chemical structure of molecular chains, cellular structure, and material macrostructure are summarized. Furthermore, the relationship between the structure and elastic properties of thermoplastic elastomer foams is investigated. Finally, the development for the batch foaming of thermoplastic elastomers with supercritical fluids is prospected.  
        关键词：Thermoplastic elastomers;Physical foaming;Cell nucleation and growth mechanism;Shrinkage;Resilient performance   
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        发布时间：2024-04-16

        Research Article

      • Zhen-zhen Zhou,Shun-jie Liu,Tao-tao Lang,Feng-xiang Gao,Xian-hong Wang
        Vol. 55, Issue 4, Pages: 396-406(2024) DOI: 10.11777/j.issn1000-3304.2023.23282
        摘要：Foldamer catalysts have been extensively applied in the synthesis of small molecules due to the "enzyme-like" secondary structure, while their contributions in polymer synthesis were rarely reported. Based on the polycondensation reaction of aluminum bis-aminoporphyrin and 2,‍5-diacylchloropyridine, we reported an aluminum porphyrin aromatic amide foldamer catalyst (AAF), and its foldamer structure was verified by the circular dichroism spectrum. The foldamer catalyst AAF effectively (turnover frequency, TOF=300‍‒‍1250 h-1) catalyzed the copolymerization of carbon dioxide and epoxides with high polymer selectivity (99%). It is worth mentioning that, this catalyst can realize the copolymerization of carbon dioxide and propylene oxide even in the absence of cocatalyst with a TOF of 525 h-1 and polymer selectivity of 95%, which also exhibits an enzyme-like optimum temperature of 80 ℃. Additionally, it could also catalyze the copolymerization of carbon dioxide and cyclohexane oxide, the catalytic activity (TOF=550‍‒‍1250 h-1) was linearly positively correlated with carbon dioxide pressure (1‍‒‍7 MPa), and the polymer selectivity and carbonate units were all over 99%. Herein, we reported an aluminum porphyrin based aromatic amide foldamer catalyst, which broadens the application of foldamer catalysis in polymers and opens up new avenues for the study of aromatic amide foldamers in the field of catalysis.  
        关键词：Aluminum porphyrin;Aromatic Amide Foldamer;Carbon dioxide;Epoxides;Cooperative Catalysis   
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        发布时间：2024-04-16
      • Yuan Yao,Pin He,Xin-feng Tao,Bin-bin Xu,Shao-liang Lin
        Vol. 55, Issue 4, Pages: 407-418(2024) DOI: 10.11777/j.issn1000-3304.2023.23269
        摘要：Self-assembly of amphiphilic copolymers presents a promising platform for the design and synthesis of nanomaterials, depending heavily on the topological polymer chemistry and properties of their compositions. In particular, asymmetric molecular brushes are composed of two different side chains grafted on a linear backbone, possessing distinct assembly behaviors in comparison with conventional linear copolymers, owing to the asymmetric double-brushes and combined effects of backbone and brushes. Additionally, the introduction of unique functionalities and responsiveness into the self-assembly system of asymmetric molecular brushes endows extra opportunities to pursue morphologic diversity and intriguing functionalities. In this study, a novel functional acrylate monomer Br-acrylate-Cl with Br-containing initiating group and alkylchlorine group was designed and synthesized. The functional macro-agent, poly(Br-acrylate-Cl), was first prepared by reversible addition-fragmentation chain transfer (RAFT) homopolymerization of Br-acrylate-Cl monomer. Azobenzene-containing side chains were then directly grown from the backbone via atom transfer radical polymerization (ATRP) of azobenzene-containing monomer initiated by the pendant Br-containing initiating groups on the backbone, affording PA-g-PAzo molecular brushes. The obtained PA-g-PAzo molecular brushes were subsequently used in postpolymerization substitution to generate PA-g-PAzo/(TPE-HEG) asymmetric molecular brushes with azobenzene and hexaethylene glycol-containing side chains and tetraphenylethylene groups. Due to the special architecture and inter/intramolecular association of pendant azobenzene and tetraphenylethylene groups, PA-g-PAzo/(TPE-HEG) asymmetric molecular brushes exhibited unique self-assembly behavior. Therefore, π‍-‍π and solvophobic interaction-driven self-assembly of PA-g-PAzo/(TPE-HEG) in CH3OH-THF mixed solvents was studied, and the morphologies of the assemblies were characterized by transmission electron microscopy (TEM). Well-defined bundle-like aggregates, sheaf-like aggregates, and 2D platelets were constructed via self-assembly of PA-g-PAzo/(TPE-HEG) through a heating-cooling-aging process. The formation of sheaf-like aggregates was systematically investgated. Intriguingly, the azobenzene moieties undergo trans-cis isomerization upon UV irradiation and further promote a morphology evolution of the assemblies, leading to the formation of rectangular platelets. Our study presents an efficient method for preparing asymmetric molecular brushes based on the functional monomer stragtegy, and opens a new avenue to design molecular-brush-based nanomaterials with tunable morphologies.  
        关键词：Molecular brushes;Azobenzene;Sheaf-like aggregate;Photo-responsiveness;Self-assembly   
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        发布时间：2024-04-16
      • Zi-hao Jiang,Xin-yuan Li,Li-wei Hui,Yu-ze Kang,Fei Wang,Hao Cai,Li Pan,Yue-sheng Li
        Vol. 55, Issue 4, Pages: 419-427(2024) DOI: 10.11777/j.issn1000-3304.2023.23247
        摘要：Using 1-octene and 1-decene as monomers, and a catalytic system of TiCl4 (a fourth-generation Ziegler-Natta catalyst) loaded on MgCl2 as the main catalyst, triethylaluminium (Et3Al) as a co-catalyst, and methylcyclohexyldimethoxysilane (CHMDMS) as the external electron donor, under both magnetic stirring and mechanical stirring conditions, respectively, a series of poly-α-olefin (PAO)-based drag reducer were successfully prepared. As proven by high-temperature gel permeation chromatography, the newly obtained polymers not only had very high molecular weight, (weight average molecular weight of most of the polymers was higher than 3×106), but also had very narrow molecular weight distribution (polymer dispersity index was lower than 3.0 for most of the polymers), suggesting a uniform distribution of all polymer chains. The obtained polymers were characterized by 13C-nuclear magnetic resonance (13C-NMR), differential scanning calorimetry (DSC), thermal gravimetric analyzer (TGA) and X-ray diffraction (XRD), respectively. It turned out that target polymers with expected composition were obtained. Most of the polymers were amorphous, making them well-soluble in oils. All polymers showed high decomposition temperature beyond 300 ℃, much higher than working temperature of drag reducers. The loop pipeline cycling experiment indicated that the drag reduction efficiency of the newly obtained polymers was greatly improved compared with those of commercial products and previous reports.  
        关键词：Drag reducer;Poly-α-olefin;Drag reduction efficiency;Ziegler-Natta catalysts   
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        发布时间：2024-04-16
      • Hao Liu,Jia-ling Tan,Wei-dong Yu,Jia-yin Liu,Chao-xia Wang
        Vol. 55, Issue 4, Pages: 428-437(2024) DOI: 10.11777/j.issn1000-3304.2023.23258
        摘要：Polydiacetylene is a kind of polymer that can transform conjugate skeleton to lead to change color when the ambient temperature changes. But its thermochromic temperature is high and it is difficult to recover after conformation transformation. The thermochromic materials which meet the application of human temperature intelligent sensing can be obtained by head-group modification. In this study, dopamine was used to modify diacetylene monomer to create covalent bonds at the head group. A double polymerization system (Poly-PCDA-PDA) was produced under 254 nm UV light to investigate the effect of polydopamine on the thermochromic temperature and the reversible recovery property. Composite thermochromic materials were prepared by combining PCDA-PDA with thermoplastic polyurethane (TPU). After modification, the polydiacetylne, whose phase transition point was reduced from 62 ℃ to about 39 ℃, can transform color from blue to purple at 35 ℃. The thermal performance analysis showed that the combination of TPU improved the stability of PCDA-PDA without affecting the thermochromism performance. The thermochromic material is more in line with the application scenario of human temperature environment. This paper provides a strategy for further modification of polydiacetylene by covalent bonding after dopamine-substituted head group, which is expected to play an important role in the research of polydiacetylidene temperature sensing materials.  
        关键词：Thermochromism;Polydiacetylene;Dopamine;Polyurethane;Self-assembly   
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        发布时间：2024-04-16
      • E Xu,Yu Huang,Lu-lu Xiong,Han-zhao Kuang,Hai Zheng,Yi Wang,Xiao-chao Xia,Feng Wang,Xu-dong Cui,Yan-hao Huang
        Vol. 55, Issue 4, Pages: 438-451(2024) DOI: 10.11777/j.issn1000-3304.2023.23261
        摘要：A post-functionalized photosensitive polyether material prepared by ring-opening polymerization (ROP), as well as side group modification that conducted by "click chemistry" is reported in this work. Allyl glycidyl ether (AGE) was used as the precursor to prepare poly(allyl glycidyl ether) (PAGE) by anionic ring-opening polymerization under the catalysis of cesium pivalate. Then the photosensitive moieties of cinnamoyl chloride were introduced onto side chains of PAGE prepolymer by two-step reactions of thiol-ene "click chemistry" and esterification, aiming to prepare polyether with photosensitive properties. The main chain length of PAGE prepolymer and the grafting rate of cinnamoyl chloride side groups can be flexibly controlled by adjusting the monomer/initiator ratio and grafting reaction time, respectively. After casted and photocured, the photosensitive PAGE film possesses a low glass transition temperature (Tg), and exhibits rapid and reversible deformation characteristic undergoing a reversible [2+2] cycloaddition reaction triggered by ultraviolet light with a wavelength of 365 and 254 nm. From the aspect of designing and optimizing the polyether main chain/side branches structure via ring-opening polymerization and "click chemistry" reaction design, the results provide practical ideas for broadening the service temperature window of photo-functional polyether, and improving its photo-induced deformation sensitivity. The obtained polyether materials also show some potential applications in the fields of controlled drug release and flexible intelligent robots.  
        关键词：Allyl glycidyl ether;Polyether;Cinnamyl chloride;photo-responsiveness;Photo-induced deformation   
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        发布时间：2024-04-16
      • Jian-ming Zhong,Jun-ming Dai,Yu Zhang,Qing-mei Zhao,Xu Zhang,Yong-bing Zhuang
        Vol. 55, Issue 4, Pages: 452-461(2024) DOI: 10.11777/j.issn1000-3304.2023.23245
        摘要：For proton exchange membranes used in fuel cells, it is critical to develop materials that can withstand a wide range of industrially relevant temperatures. In this work, novel polybenzimidazole (TB-PBI-N) containing Tröger's base (TB) units was synthesized and used as a filler to be blended with TB-based polyimide (PI-TB-N) for five types of phosphoric acid-doped composite proton exchange membranes. The chemical structures, mechanical properties, thermal and oxidative stability, acid adsorption, swelling ratios, proton conductivity (σ) and power density of H2O/air fuel cells (PD) of the composite membranes were characterized by Fourier transform infrared spectroscopy (FTIR), magnetic resonance spectroscopy (1H-NMR), thermogravimetric analysis (TGA), and tensile tests. The effect of incorporated TB-PBI-N filler on the properties of the composite membranes were investigated in details. The results showed that the tensile strength of the composite membranes without phosphoric acid doping were 87.3-129.5 MPa, and 3.7-9.5 MPa for the acid doped membranes. The phosphonic acid uptake were 235.3%-288.7% after doping with the swelling ratios ranging between 13.9%-25.0%, and the composite membranes can conduct protons at wide temperature range from 30 ℃ to 160 ℃. The maximum σ and PD of the composite membranes reached up to 94.3 mS/cm and 334.6 mW/cm2, respectively. Furthermore, it was found that the introduction of TB-PBI-N filler improved the mechanical properties and the dimensional stability for the phosphoric acid doped membranes. In addition, the TB units in TB-PBI-N have additional base sites, which enhanced acid adsorption capacity and greatly improved the σ values of the membranes. Among the five membrane types, the TB-PI-5PBI membrane showed a tensile strength of 116.8 MPa, proton conductivity of 67.7 mS/cm (160 ℃, 0% RH). More importantly, the PD values of the fuel cells reached 58.9, 224.7 and 334.6 mW/cm2 at 30, 80 and 160 ℃, respectively, indicating excellent application prospect in a wide temperature range under non-humidity environment.  
        关键词：Polyimide;Polybenzimidazole;Tröger's base;Proton Exchange Membranes;Composite Membranes   
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        发布时间：2024-04-16
      • Cheng-yu Shi,Ying Zhou,Chun-yu Zhao,Shao Yang,Ling He,Ai-zhao Pan
        Vol. 55, Issue 4, Pages: 462-472(2024) DOI: 10.11777/j.issn1000-3304.2023.23251
        摘要：Hydrogels present broad application prospects in the field of conservation of cultural heritage due to their strong adhesion, high transparency, high flexibility and controllable mechanical strength. In this study, a novel bentonite-based hydrogel (AR-gel) material for efficient adhesive conservation of the damaged and fractured sandstone-based cultural heritage was fabricated via introducing functionalized bentonite into the acrylamide-based hydrogel, and the components, forming temperature and time were optimized. The bentonite-based hydrogel improved the compatibility with sandstones, and presented excellent adhesion without any obvious trace at the adhesion joints. While, the adhesive on sandstones kept primary state without white or discoloration, which further indicated its non-destructive bonding protection. In addition, the overflow during the bonding process can be easily removed with water without any trace. The morphology and properties of the repaired sandstone can keep consistent with primary sandstones, which avoid the secondary damage to the sandstones during the adhesion process. The high-durability conservation of AR-gel material on sandstone was verified by severe freezing and thawing aging cycle and salt crystallization-wet/heat cycle aging test, and the high-durability conservation mechanism was deeply analyzed: sandstone and AR-gel were firmly bonded by strong hydrogen bond, Si－O－Si bond, Si－O－M bond, protonation and ionic bond, mechanical bite, and so on. Besides, AR-gel presented excellent bonding properties for various types of cultural relics, such as glass, metal, sandstone, ceramics, and pottery. The development of this work was expected to provide a durable cultural relic bonding conservation material with wide application prospects.  
        关键词：Bentonite;Hydrogel;Adhesive restoration of cultural relics;Long-term protection;Adhesion universality   
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        发布时间：2024-04-16
      • Ming-wei Guo,Li-ming Huang,Zhi-feng Zhao
        Vol. 55, Issue 4, Pages: 473-484(2024) DOI: 10.11777/j.issn1000-3304.2023.23231
        摘要：To quantitatively explore the critical contributions of both molecular weights and blending ratios to the formation of stereocomplex (SC) crystallization in the poly(L-lactide)/poly(D-lactide) (PLLA/PDLA) enantiomeric blends. A series of PLLA/PDLA racemic blends were prepared by controlling the enantiomeric chain length differences and blending ratios, and it was found that in the enantiomeric blends with an enantiomeric chain length average degree of polymerization (DP¯) about 60 or less, when the two enantiomers had exactly the same chain lengths with the same blending ratios, SCs were formed that were more ordered with less entanglement or the amorphous regions. On the other hand, when the two enantiomeric chain lengths are unequal, the excess segments of the longer ones could remain amorphous on the surface of the SC crystallization, or complex with the other shorter enantiomers, or tightly pack between the excess segments to form homocrystals (HCs), depending on the dual effects of the difference in chain lengths and the blending ratios: when the difference in chain lengths is not significant (xL<xD<2xL where x is the chain segment length, and L or D refer to the poly(lactide) configuration), since xD does not exceed 2 times xL (xD<2xL), a longer chain segment cannot accommodate the two shorter chains in the series, and the excess segments of the longer segments could stay amorphous on the SC crystallization surface. Although there is competitive crystallization between SC crystallization and HC crystallization, the former is preferred at appropriate blending ratios; when the difference in chain length (xD≥2xL) widens further, there will be enough space in the longer chain to accommodate more than one short enantiomeric chain, which means that the equal-ratio asymmetric PLLA/PDLA blends fail to form a particularly uniform single SC crystallization, and HC crystallization is found to be signs of HC crystallization. Meanwhile, the lengthy segments of the longer enantiomeric chains on the surface of the SCs could be further matched with another additional short enantiomeric chain to form multi-complexation.  
        关键词：Polylactide;Stereo-complexation;Blending ratios;Molecular weight;Enantiomeric blends   
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        发布时间：2024-04-16
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