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Polybutene-1 with form I crystals exhibits excellent creep resistance and environmental stress crack resistance. The filaments of polybutene-1 and its random copolymer with 4 mol% ethylene co-units were produced via extrusion melt spinning, which are expected to be in form I states and show outstanding mechanical properties. The variances in microstructure, crystallization–melting behavior, and mechanical properties between homopolymer and copolymer filaments were analyzed using SEM, SAXS/WAXD, DSC, and tensile tests. The crystallization of form II and subsequent phase transition into form I finished after the melt-spinning process in the copolymer sample while small amounts of form II crystals remained in homopolymer filaments. Surprisingly, copolymer filaments exhibited higher tensile strength and Young's modulus than homopolymer filaments, while the homopolymer films showed better mechanical properties than copolymer films. The high degree of orientation and long fibrous crystals play a critical role in the superior properties of copolymer filaments. The results indicate that the existence of ethylene increases the chain flexibility and benefits the formation of intercrystalline links during spinning, which contributes to an enhancement of mechanical properties. The structure–property correlation of melt-spun PB-1 filaments provides a reference for the development of polymer fibers with excellent creep resistance. [ABSTRACT FROM AUTHOR]

The precise design and fabrication of electrode materials is important for the development of high-performance flexible supercapacitors. Cu 2 O/MXene film electrodes with an interconnected conductive network structure are prepared in this work by in situ growth of Cu 2 O nanoparticles in a Ti 3 C 2 Tx dispersion, followed by alkali induction and vacuum filtration. The interconnected crimpled Ti 3 C 2 Tx structure produced by alkali induction not only works as the self-supported conductive network of the thin film electrode but also demonstrates sufficient open pores and high surface area, which can promote electrolyte penetration and increase active sites for energy storage. The synergy between Cu 2 O nanoparticles and the crimpled Ti 3 C 2 Tx framework leads to good structural stability and electrochemical performance. The results show that the Cu 2 O/MXene electrode exhibits a high specific area capacitance of 1518 mF cm−2 in 1 M LiCl electrolyte. In addition, the all-solid-state flexible supercapacitor fabricated with the Cu 2 O/MXene electrode exhibits excellent cyclic stability and flexibility; the capacity retains 94.3% after 10,000 charge and discharge cycles, and the energy storage performance remains stable after 50 mechanical bending cycles. • In situ growing Cu 2 O in Ti 3 C 2 Tx dispersion helps achieve higher energy density. • The interconnected network structure benefits charge transfer. • The interaction between Cu 2 O and MXene improve the energy storage performance. [ABSTRACT FROM AUTHOR]

• 1T-MoS 2 was applied as a flexible and functional "spacer" to hybridize with Ti 3 C 2 T X MXene, forming flexible capacitive freestanding films. • The insertion of electrically neutral pseudocapacitive could mitigate the restacking of Ti 3 C 2 T X MXene layers and improves the capacity of the composite paper. • The supercapacitor fabricated with acidic gel electrolyte and composite electrode with randomly stacked MXene and 1T-MoS 2 in a mass ratio of 6:1 demonstrated optimal performance. In the case of increasing shortage of non-renewable resources, developing high-efficiency and high-capacity energy storage devices is critical. Supercapacitors have the potential of high-efficiency and high-capacity. MXene and 1T-MoS 2 are two kinds of high performance pseudocapacitive materials. However, the stacking and aggregation of MXene nanosheets greatly reduce its capacity. The poor conductivity of 1T-MoS 2 also limits the full expression of its excellent pseudocapacitive performance. A flexible MXene/1T-MoS 2 composite paper electrode is designed and prepared in this work where the restacking of MXene can be relieved and the whole electrode maintains the conductivity. The interior stacking structure of MXene and 1T-MoS 2 in the composite paper, as well as the gel electrolyte type are explored. The device constructed with the electrode composed of randomly stacked MXene and 1T-MoS 2 (mass ratio 6:1) and acidic electrolyte (PVA/H 2 SO 4 gel electrolyte) demonstrates the optimal performance. The specific areal and volumetric capacitances reach 561.2 mF cm−2 and 1268.17 F cm−3 at the current density of 0.8 mA cm−2 respectively, outperforming most of the previously reported values for MXene based supercapacitors tested in gel electrolyte. The supercapacitor has excellent deformation durability and long cycle stability, demonstrating promising prospect in future flexible electronics. [Display omitted] [ABSTRACT FROM AUTHOR]

Although polypropylene (PP) foams fabricated by microcellular injection molding (MIM) have been widely studied and globally applied, it is still a big challenge to achieve lightweight products with high mechanical performance. Herein, the MIM method assisted by a fast cooling design was applied to prepare lightweight bimodal nanoporous PP foams with high toughness. A specific mold with a thin cavity was designed to achieve rapid cooling rate during MIM process, and to further accelerate crystallization and refine crystals, which was verified by visualization results, DSC curves, and WAXD patterns. Thus, nanocellular PP foams were prepared, whose high toughness was presented in tensile testing, especially for bimodal cellular foams, more than 327% higher than that of microcellular foams, and up to 53% higher than that of solid. It is owing to the introduced matrix craze, shear yielding, and larger plastic zone by nanocells and the transformed crack propagation direction by microcells. Therefore, this novel toughening method paves a promising prospect for MIM technology to achieve lightweight and tough products for industrial applications. Unlabelled Image • High-tough and lightweight PP/talc bimodal nanoporous foams were fabricated by microcellular injection molding. • Fast cooling pronouncedly enhanced crystallization and contributed to formation of nanocells. • Bimodal cells significantly toughened PP composite foams by changing crack propagation direction. [ABSTRACT FROM AUTHOR]

Polybutene-1 (PB-1) exhibits excellent mechanical properties, while an unavoidable polymorphic transition from a metastable form II to the stable form I occurs after solidification from the molten state. This transition goes along with a deformation of the crystal lattice corresponding to a lateral shrinkage and normal elongation of about 20% and 12%, respectively. Here we study the semicrystalline morphology before and after the transition using small-angle X-ray scattering (SAXS) and differential scanning calorimeter (DSC). Scattering curves of samples with form II crystals could be well described by a model of layer-like stacked lamellar crystals. However, the scattering signal of form I samples showed additional scattering contributions at higher scattering vectors, indicating the generation of fine structures during the transition, much smaller than lamellar long spacing. The lamellar thickness increased less than the factor of 1.12, expected from the elongation of the lattice. The results indicate that the large lamellar crystals split up into blocks during the transition creating new interstitial spaces within the lamellae. This process is caused by the fact that the laterally extended lamella of form II cannot shrink as a whole due to the connectivity of the chains emanating from the crystals and due to possible overcrowding of the chain segments at the crystalline/amorphous interfaces. Image 1 • The semicrystalline morphology before and after the form II to I transition in PB-1 was studied using SAXS techniques. • Fine structures much smaller than lamellar long spacing were formed after form II to I transition in PB-1. • Lamellar thickness increases a bit after phase transition, but not to full extent of the elongation of the crystal lattice. [ABSTRACT FROM AUTHOR]

Phase composition and molecular mobility were studied using 1H NMR T 2 relaxometry in isotactic polybutene-1 (iPB-1) with two polymorphs - form I and II crystals. Several types of NMR relaxation methods and data analysis were evaluated for determining the most reliable way for studying physical phases in iPB-1. Three-phase model provided the most appropriate description of the phase composition in iPB-1, i.e., a crystal-amorphous interface separates the crystalline and the amorphous phases. Due to complex molecular mobility in iPB-1, the amount of rigid fraction should be considered as NMR crystallinity number. Two types of chain segments are present in the amorphous phase: (1) chain segments with anisotropic mobility due to chain anchoring to crystals and chain entanglements; and (2) highly mobile chain end segments. The polymorphic phase II to I transition causes significant immobilization of polymer chains in the crystalline and the amorphous phases. Molecular weight of iPB-1 largely influences phase composition and molecular mobility in crystalline and amorphous phases. Image 1 • Phase composition and molecular mobility in isotactic polybutene-1 are studied using 1H NMR T 2 relaxometry. • The three-phase model provides the best description of the phase composition. • Advantages and disadvantages of different types of T 2 relaxation experiments are discussed. • The polymorphic phase II to I transition causes decrease in chain mobility in the crystalline and the amorphous phases. • Molecular weight of iPB-1 largely influences phase composition and molecular mobility in crystalline and amorphous phases. [ABSTRACT FROM AUTHOR]

Hydrogel coatings that can endow various substrates with superior properties (e.g., biocompatibility, hydrophilicity, and lubricity) have wide applications in the fields of oil/water separation, antifouling, anti-bioadhesion, etc. Currently, the engineering of multifunctional hydrogel-coated materials with superwettability and water purification property using a simple and sustainable strategy is still largely uninvestigated but has a beneficial effect on the world. Herein, we successfully prepared poly(2-acrylamido-2-methyl-1-propanesulfonic acid) hydrogel/β-FeOOH-coated poly(vinylidene fluoride) (PVDF/PAMPS/β-FeOOH) membrane through free-radical polymerization and the in situ mineralization process. In this work, owing to the combination of hydrophilic PAMPS hydrogel coating and β-FeOOH nanorods anchored onto PVDF membrane, the resultant PVDF/PAMPS/β-FeOOH membrane achieved outstanding superhydrophilicity/underwater superoleophobicity. Moreover, the membrane not only effectively separated surfactant-stabilized oil/water emulsions, but also possessed a long-term use capacity. In addition, excellent photocatalytic activity against organic pollutants was demonstrated so that the PVDF/PAMPS/β-FeOOH membrane could be utilized to deal with wastewater. It is envisioned that these hydrogel/β-FeOOH-coated PVDF membranes have versatile applications in the fields of oil/water separation and wastewater purification. [ABSTRACT FROM AUTHOR]

Polyamide 6 (PA6) materials with different degrees of long chain branching (LCB) were prepared via extrusion through varying the addition of chain extender. The LCB degree was quantitatively determined by using a rheological method based on macromolecular dynamic models. The topological structures of long-chain branching and crosslinked network were effectively distinguished through rheological percolation analysis so that modified PA6 with ultra-high LCB level was obtained. The XRD analysis indicated that LCB modification favored the generation of the γ-form, and the γ-form content of LCB-PA6 increased with increasing degree of LCB, which could provide a reasonable explanation for the high Izod impact strength of ultra-high LCB-PA6. Another reason for the great enhancement of impact toughness was the strong interfacial interaction between LCB molecules and virgin PA6 matrix. A large number of fibrillar ligaments and cavities during crack propagation were observed in the SEM analysis. Unlabelled Image • The topological structures of LCB and crosslinked network were effectively distinguished through rheological percolation analysis. • Ultra-high branched PA6 presented a high melt strength and favorable impact toughness. • Good correlation between γ-form content and impact toughness was verified. • Toughening mechanism of LCB PA6 was firstly studied based on XRD and SEM analysis. [ABSTRACT FROM AUTHOR]

Transcrytallinity plays a critical role in the interfacial crystalline morphology. However, it is rather rare to observe transcrytallinity grown from completely molten surface without using nucleating agent. Herein, we utilize melt penetration engineering to provide a sheared polymeric melt interface in order to tailor interfacial polypropylene (PP) crystalline morphology from β-transcrystals (β-TC) to β-cylindrites. The investigated system containing polymorphic PP as penetrating phase and polyethylene (PE) as penetrated layer were selected. Interestingly, we can clearly observe a continuous and ordered β-transcrystals (β-TC) at PP/PE interface and morphological transition from β-TC to β-cylindrites upon using higher molecular weight PE as the penetrated melt. Foreign PE surface plays an indispensable role in transcrystallinity formation since only α-spherulites were developed during identical PP penetrating PP process. The effects of surface-induced crystallization as well as coupling flow and temperature field have been discussed, in order to offer an insight on interfacial morphological transition. Consequently, melt penetration engineering can provide a facile and scalable route to achieve designed interfacial morphology from β-TC to β-cylindrites, which opens a new perspective to develop interfacial crystalline morphology. [Display omitted] • Melt penetration to design interface. • Tunable structure from transcrystal to cylindrite. • β-interfacial morphology is developed. [ABSTRACT FROM AUTHOR]

Water pollution caused by industrial oily wastewater, is world-widely concerned by both scientific and practical researches, owing to its catastrophic destruction to natural environment, which highlights the urgency of producing green and advanced separation materials. Herein, a novel approach was proposed to fabricate oil-absorbing and oil/water-separating microcellular polypropylene (PP)/carbon nanotubes (CNTs)/sorbitol nanocomposites using a simple, green, and facile microcellular foaming technology. Owning to the effectively modified crystallization via introducing CNTs/sorbitol derivatives, the ultralight and highly-reticulated PP microcellular foam was prepared with an open-cell content of 99.4% and an expansion ratio of 50, which facilitated the creation of nano-porous structures on cell walls. Hence, the as-prepared PP nanocomposite foam presented pronounced absorption capacity of 40 g/g for applied oils with recovery efficiency of 97.2%, superior thermal-insulating and mechanical performance. Furthermore, the as-achieved unique hierarchical porous structures of the PP/CNT/sorbitol foam contributed to the outstanding oil/water separation capability, separation efficiency of up-to 97.6%, ascribed to its superhydrophobicity, capillary penetration action, high porosity and open-cell content. Therefore, this work provided new insight into the feasibility of advantageous, high-efficiency, environmentally friendly, and profitable PP-based foams as oil absorbents, which, to the best of our knowledge, outperform conventional polymer absorbents in treatment of oily wastewater. [Display omitted] • Superlight PP/CNT/sorbitol foams with high open-cell content were prepared by microcellular foaming. • Undifferentiated absorption capacities of more than 40 g/g for 10 kinds of oil were achieved by PP/CNT/sorbitol foams. • PP/CNT/sorbitol foams showed outstanding oil/water separation efficiencies, up to 97.6%. • PP/CNT/sorbitol foams exhibited thermal conductivity as low as 28.18 mW∙m-1∙K-1 with advanced compressive strength. [ABSTRACT FROM AUTHOR]