基于聚磷腈可降解电活性材料的合成及其降解行为研究

以六氯环三磷腈为原料,加热开环聚合制备了聚二氯磷腈,再分别以苯胺五聚体为功能单元、甘氨酸乙酯和赖氨酸为调节基团,通过两步亲核取代反应,合成了两种可用于神经支架工程材料的可降解电活性高分子聚[(甘氨酸乙酯/苯胺五聚体)磷腈](PGAP)和聚[(赖氨酸/苯胺五聚体)磷腈](PLAP)。通过红外、热重、核磁、循环伏安、紫外等对聚合物进行了全面的表征。在此基础上,重点研究了氨基酸类侧链取代基对聚磷腈降解行为的影响。研究结果表明,侧链氨基酸类取代基的类型和比例对此高分子材料的降解行为有着关键性影响。其降解速率随着取代基比例的增加而加快,此外,随着氨基酸侧链基团极性的增加,降解速率增加。     

Biodegradable Poly(butylene adipate-co-terephthalate) composites reinforced with bio-based nanochitin: Preparation,enhanced mechanical and thermal properties

The accumulation of nonbiodegradable petrochemical-based polymers in the environment motivates the development and use of low-cost, eco-friendly, and biodegradable polymers. A series of biodegradable poly(butylene adipate-co-terephthalate) composites reinforced by sustainably sourced nanochitin were successfully prepared using melt blending and compression molding methods. Structural, thermal, and mechanical characterizations of poly(butylene adipate-co-terephthalate) (PBAT)/nanochitin composites were performed. SEM revealed that the nanochitin was uniformly dispersed throughout the PBAT matrix at low contents (<2 wt %), while DSC analyses revealed a corresponding increase in the crystallinity (32.6% enhancement) of the PBAT matrix. The tensile strength and elongation at break of the PBAT/nanochitin composite containing 0.5 wt % nanochitin were higher by 82.5 and 64.2%, respectively, compared with pristine PBAT. The Chitin-0.5 composite also showed improved thermal stability compared with PBAT (the char yield improved by 8%) due to the uniform dispersion of nanochitin in the PBAT matrix. The enhanced performance of the PBAT/nanochitin composites, prepared without an added compatibilizer, informs the development of improved biodegradable PBAT-based polymers. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48485.     

Effect of pine resin derivatives on the structural,thermal, and mechanical properties of Mater-Bi type bioplastic

The effect of three additives derived from pine resin, namely, gum rosin (GR) and two pentaerythritol ester of GR, Lurefor (LF) and Unik Tack (UT), in 5, 10, and 15 wt %, on the properties of Mater-Bi, based on plasticized starch, poly(butylene adipate-co-terephthalate), and poly(ε-caprolactone) (PCL), obtained by injection molding processes, was studied. The mechanical, microstructural, and thermal properties were evaluated. LF had a cohesive behavior with the components of Mater-Bi, increasing the toughness of the material up to 250% accompanied by an increase of tensile modulus and tensile strength. UT had an intermediate behavior, conferring cohesive and plasticizing effects, allowing an increase of 105% in impact resistance. GR had a more marked plasticizing effect. This allows processing temperatures of about 50 °C lower than those used for neat Mater-Bi. In addition, an increase of the elongation at break, toughness, and impact resistance in 370, 480, and 250%, respectively, was achieved. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48236.     

Hydrogen-bonding assembly of heteropolyacid and poly(vinyl alcohol) for strong,flexible, and transparent UV-protective films

Although many preparation approaches have been developed, it remains a huge challenge to achieve ultraviolet (UV)-protection films that combine high transparency, excellent UV-shielding, and mechanical properties. Herein, we demonstrate a facile and eco-friendly process for fabricating strong, flexible, and transparent UV-protective poly(vinyl alcohol) (PVA) films by exploiting silicomolybdic acid (SiMoA) as UV absorber and reinforcing phase. Fourier-transform infrared analysis confirms the formation of strong hydrogen-bonding interactions between PVA and SiMoA. The glass-transition temperature, mechanical properties, and UV-shielding stability of the UV-protective PVA composite films obviously increase with increasing the content of SiMoA. By incorporation of only 2 wt % SiMoA, the UV-protective PVA composite film can block more than 90% of UV light in the entire UV regions and retain high visible light transparency (up to 95%). Simultaneously, the UV-protective PVA composite film presents excellent mechanical properties with a tensile strength of 65.2 MPa and an elongation at break of 172.6%, which are 72.0 and 69.5% higher than that of pristine PVA films. This work provides a simple but effective approach for creating strong, flexible, and transparent UV-blocking polymeric materials via hydrogen-bonding assembly, which are expected to have wide application prospects in UV-protection field. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48813.     

Synthesis,properties, and biodegradability of three-branched copolyamide (4/6)

Previous studies on polyamide 4, excellent properties, functionalities, and biodegradation in natural condition have been shown. In this study, three-branched (star-shaped) copolyamides constituted of polyamide 4 and polyamide 6 constitutional unit were synthesized by anionic ring-opening copolymerization of 2-pyrrolidone with ε-caprolactam. The thermal and mechanical properties and the biodegradability of the obtained copolyamides have been systematically investigated. The weight-average molecular weight of the copolyamides was as high as tens of thousands (M_w 10–80 × 10³ g/mol). The composition of the copolyamides was approximately in accord with the monomer feed ratio, thereby being controllable. The thermal and mechanical properties changed readily as the composition was varied (T_m 146–266°C, ΔH_m 10–70 J/g, T_d 278–369°C, tensile strength 28–64 MPa, elongation at break 80–750%). The copolyamide having 2-pyrrolidone unit of 96–51 mol% exhibited biodegradability by an activated sludge. The biodegradation of the copolyamide proceeded uniformly without disproportion in constitutional unit.     

生物基异己糖醇聚酯的制备及其构效关系研究进展

异己糖醇是一类碳水化合物衍生二元醇,具有高刚性、手性、亲水性和低毒等特性,在制备新型生物基、生物可降解高分子材料方面具有广阔的发展前景。围绕近年来研究较为充分的全脂肪型及半芳香型异己糖醇基均聚酯与共聚酯,综述了其合成、热学性能、力学性能、生物降解性能及潜在应用,探讨此类聚酯的高效聚合反应工艺及构效关系。异己糖醇结构单元的引入可有效提高聚合物的玻璃化转变温度,以及促进其水解和生物降解性能,在构建具有更高性能的环境友好型聚酯方面具有较高潜力,有望应用于工程塑料、纤维、生物医药等领域。此类生物基聚酯的大规模商业化需进一步开发更高效、温和的聚合反应工艺以攻克其热敏感和热降解问题。     

Production of hyaluronic‐acid‐based cell‐enclosing microparticles and microcapsules via enzymatic reaction using a microfluidic system

This article describes the preparation of cell‐enclosing hyaluronic acid (HA) microparticles with solid core and microcapsules with liquid core through cell‐friendly horseradish peroxidase (HRP)‐catalyzed hydrogelation. The spherical vehicles were made from HA derivative possessing phenolic hydroxyl moieties (HA‐Ph) cross‐linkable through the enzymatic reaction by extruding cell‐suspending HA‐Ph aqueous solution containing HRP from a needle of 180 μm in inner diameter into the ambient coaxial flow of liquid paraffin containing H₂O₂ in a microtubule of 600 μm in diameter. By altering the flow rate of liquid paraffin, the diameters of gelatin and HA‐Ph microparticles were varied in the range of 120–220 μm and 100–300 μm, respectively. The viability of the enclosed human hepatoma HepG2 cells in the HA‐Ph microparticles of 180 μm in diameter was 94.2 ± 2.3%. The growth of the enclosed HepG2 cells was enhanced by decreasing the HRP concentration. The microcapsules of 200 μm in diameter were obtained by extruding HA‐Ph aqueous solution containing thermally liquefiable cell‐enclosing gelatin microparticles of 150 μm in diameter using the same microfluidic system. The enclosed cells grew and filled the cavity within 10 days. Spherical tissues covered with a heterogeneous cell layer were obtained by degrading the microcapsule membrane using hyaluronidase after covering the surface with a heterogeneous cell layer. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43107.     

Optimizing the mechanical and physical properties of thermoplastic starch via tuning the molecular microstructure through co‐plasticization by sorbitol and glycerol

Nowadays, environmental hazards caused by plastic wastes are a major concern in academia and industry. Utilization of biodegradable polymers derived from renewable sources for replacing common petroleum‐based plastics is a potential solution for reducing the problem. In this regard, starch has become one of the most promising alternatives to non‐biodegradable polymers for depleting plastic waste thanks to its low expense, abundance, renewability and biodegradability. However, the main drawbacks of starch are its poor processability, weak mechanical properties and severe hydrophilicity. In this work, thermoplastic starch (TPS) samples have been prepared using glycerol and sorbitol as co‐plasticizers in a laboratory co‐rotating twin screw extruder. Based on the mechanical test results, glycerol caused higher elongation to break but had lower tensile strength and elastic modulus compared to sorbitol plasticized starch. Fourier transform infrared spectroscopy and DSC results indicated that the hydrogen bond interaction between starch chains and plasticizers could be improved by replacing glycerol by sorbitol, which resulted in higher resistance against retrogradation proved by XRD results. TGA illustrated that the higher the sorbitol to glycerol ratio was, the more stable was the TPS. Using a proper amount of plasticizers (42 wt% total plasticizer, sorbitol to glycerol ratio 2:1) led to the preparation of a TPS sample with optimized properties including enhanced mechanical properties, high thermal stability, strong hydrogen bond formation and high resistance against retrogradation. © 2017 Society of Chemical Industry