Macromolecular Chemistry and Physics最新文献

The facile characterization of isothermal microphase separation kinetics in polyamide 6 (PA6)-based thermoplastic elastomers (TPAE-6) has long posed a challenge for the development of suitable melt spinning processes. In this study, this challenge is addressed through differential scanning calorimetry (DSC) measurements. It is assumed that the enthalpy changes of TPAE-6 during the isothermal process are a linear superposition of enthalpy changes associated with microphase separation and crystallization of PA6 in hard phases, resembling that of TPAE-6 without soft segments (TPAE-6-0). The study reveals that, as the concentration of soft segments in TPAE-6 increases, the accelerated dynamics of phase separation become stronger than the dilution of soft segments to PA6 segments during isothermal process, resulting in an increase in the microphase separation rate of TPAE-6. Furthermore, despite microphase separation, the overall crystallization rate of TPAE-6 decreases with rising isothermal temperature and varies with increasing soft segment content at different temperatures. Additionally, the crystallization mode of TPAE-6 follows two-dimensional, three-dimensional, or a combination of both crystal growth mechanisms, accompanied by a heterogeneous nucleation mechanism.

The blends of poly(butylene adipate-co-terephthalate) (PBAT), poly(propylene carbonate) (PPC), chain extender (ADR) and layered double hydroxides (LDH) are prepared by different extrusion methods. Effects of LDH and its distribution on rheology, phase morphology, mechanical properties, water vapor barrier properties and food preservation properties are investigated. Results show that when PBAT, PPC, and LDH are mixed directly, LDH is preferentially distributed in the PBAT phase. When LDH are mixed with PPC firstly and then further with PBAT, LDH mostly migrates to the interface of PBAT and PPC. The epoxy groups of ADR react with the terminal groups of the polymers to improve the interfacial compatibility. Adding LDH, the mechanical properties and barrier properties of the materials are improved and by premixing of PPC and LDH, properties of composites are further improved. Compared with PBAT/PPC blends, the tensile strength and elongation at break of PBAT/PPC(LDH-0.5)/ADR increased by 25.2% and 15.3%, respectively. The banana packaged in PBAT/PPC/LDH films maintains good freshness. It illustrates that PBAT/PPC(LDH)/ADR composites have a good application prospect in the field of barrier and food packaging based on their excellent mechanical, barrier, and preservation properties.

Olefin coordination copolymerization with polar monomers is an important topic both in academia and industry. During copolymerization, polar monomers will seriously reduce the polymerization activity and the molecular weight of the copolymer, making it difficult to balance the two and the polar monomer incorporation at the same time. In this study, a metallocene catalyst, Ph₂C(Cp)(Flu)ZrCl₂, is used for the copolymerization of ethylene with 4-penten-1-ol. The incorporation of 4-penten-1-ol can be effectively increased by the introduction of the steric phenol as the third component (TC). Depending on the cocatalyst, the activity or molecular weight can be improved. It is believed that the promotion effect may work by the interaction of the steric phenol with the catalyst or cocatalyst. It is also suggested that in this system, polymerization is terminated by deactivation-chain transfer mechanism rather than β-X elimination due to back-biting.

S. O. Aisida,* E. C. Gospel, A. Alshoaibi, D. Okeudo, R. Ijeh, and F. I. Ezema, Macromol. Chem. Phys. 2024, 225, 2300375.

The fifth author's surname and affiliation have been corrected in the article itself: https://onlinelibrary.wiley.com/doi/full/10.1002/macp.202300375

The introduction of nanomaterials as modified electrode materials into the field of electrochemical sensing is expected to improve the reliability, sensitivity, selectivity and repeatability of electrochemical sensors in detecting pollutants in the water environment. In this study, copper vanadate nanomaterials (Cu₃V₂O₇(OH)₂·2H₂O, referred to as CVO) and Cu₃V₂O₇(OH)₂·2H₂O/polyyaniline (PANI) composite nanomaterials (referred to as CVO/PANI) are successfully prepared and characterized by Fourier transform infrared spectrum (FTIR), X-ray traveling-action (XRD), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HR-TEM). The modified glassy carbon electrodes (GCE) with these two materials are used for the detection of benzoic acid (BA) and exhibit excellent electrochemical sensing performance. The results show that two pairs of semi-reversible redox peaks exist in both CVO and CVO/PANI modified glassy carbon electrode (GCE) in BA solution. The linear range of CVO and CVO/PANI nanomaterials-modified GCE is 0.01–2 mm and 0.001–2 mm, and the limits of detection are 2.16 and 0.41 µm, respectively. PANI plays important role in the electrochemical responses of BA at CVO/PANI modified GCE. PANI enhances the intensities of CV peaks and electrochemical determination ability for BA.

Front Cover: A pH/redox dual-responsive and dual chemotherapeutic PNA and hypoxia-activated AQ4N prodrug micelle is developed for targeting endogenous tumor microenvironment heterogeneity. This new micelle system provides an effective strategy to increase the drug stability and reduce toxicity or side effects under physiological conditions, trigger intracellular release of potent drugs as well as enhance the therapeutic efficiency via combined chemotherapy and hypoxia-activated cancer treatment. More details can be found in article number 2300386 by Jhin Chen Ho and Ching-Yi Chen.

The porous nature and gel network of aerogel fibers make them ideal options for personal thermal management because they can significantly cut down on energy waste. However, aerogel fibers generally suffer from poor mechanical properties and single function. Herein, the porous continuous bacterial cellulose/graphene oxide@polydopamine core–shell aerogel fibers with high strength, excellent photothermal properties, and thermal insulation are investigated by wet spinning and freeze-drying. The bacterial cellulose/graphene oxide@polydopamine aerogel fiber prepared by wet spinning method has a porous structure, which can prevent heat convection, reduce heat conduction, and suppress heat radiation, making the aerogel fiber have excellent thermal insulation properties. More crucially, graphene oxide may considerably enhance infrared radiation's capacity for heating, while polydopamine can enhance ultraviolet light absorption and boost photothermal conversion capability.