Encapsulation of Silicon Nano Powders via Electrospinning as Lithium Ion Battery Anode Materials.

Silicon-containing polyester from tetramethoxysilane, ethylene glycol, and o-Phthalic anhydride were used as encapsulating materials for silicon nano powders (SiNP) via electrospinning, with Polyacrylonitrile (PAN) as spinning additives. In the correct quantities, SiNP could be well encapsulated in nano fibers (200-400 nm) using scanning electron microscopy (SEM). The encapsulating materials were then carbonized to a Si-O-C material at 755 °C (Si@C-SiNF-5 and Si@C-SiNF-10, with different SiNP content). Fiber structure and SiNP crystalline structure were reserved even after high-temperature treatment, as SEM and X-ray diffraction (XRD) verified. When used as lithium ion battery (LIB) anode materials, the cycling stability of SiNPs increased after encapsulation. The capacity of SiNPs decreased to ~10 mAh/g within 30 cycles, while those from Si@C-SiNF-5 and Si@C-SiNF-10 remained over 500 mAh/g at the 30th cycle. We also found that adequate SiNP content is necessary for good encapsulation and better cycling stability. In the anode from Si@C-SiNF-10 in which SiNPs were not well encapsulated, fibers were broken and pulverized as SEM confirmed; thus, its cycling stability is poorer than that from Si@C-SiNF-5.

Relationship between the Co-Continuous Morphology of Immiscible Polymer Blends and the Structure of an In Situ Formed Graft Copolymer.

In order to get stable co-continuous morphology in immiscible polymer blends, besides reducing the interfacial tension, the compatibilizer should not only promote the formation of flat interface between different phases, but also not hinder the coalescence of the dispersed phase. Herein, the relationship between the morphology of the compatibilized polystyrene/nylon 6/styrene-maleic anhydride (PS/PA6/SMA) immiscible polymer blends and the structures of the in-situ formed SMA-g-PA6 graft copolymers as well as the processing conditions are studied. Two kinds of SMA are used: SMA28 (28 wt.% MAH) and SMA11 (11 wt.% MAH). After melt blending with PA6, the in-situ formed copolymer SMA28-g-PA6 has on average of four PA6 side chains, while that of SMA11-g-PA6 has only one. Dissipative particle dynamics simulation results indicate that both SMA28-g-PA6 copolymer and PS/PA6/SMA28 blends tend to form co-continuous structure, while those related to SMA11 intend to form sea-island morphologies. These results are correct only at relatively low rotor speed (60 rpm). When the rotor speed is higher (105 rpm), sea-island morphologies are obtained in SMA28 systems, while that for SMA11 ones are co-continuous. This indicates that higher shear stress can elongate the minor phase domains to form flat interfaces, while the SMA28-g-PA6 copolymers can be pulled out from the interface.

Construction of highly ductile, UV-shielding polylactide/poly(butylene adipate-co-terephthalate) biocomposites with hyperbranched polysiloxane functionalized lignin as a biocompatibilizer.

Biodegradable polylactide/poly(butylene adipate-co-terephthalate) (PLA/PBAT) blends have been widely utilized as packaging materials. However, it is urgent to develop a biocompatibilizer to improve the interfacial interaction of the biodegradable immiscible polymer blends in practice. In this paper, a novel type of hyperbranched polysiloxane (HBPSi) with terminal methoxy groups was synthesized and then utilized to functionalize lignin through a hydrosilation reaction. The HBPSi modified lignin (lignin@HBPSi) was incorporated into immiscible PLA/PBAT blends to serve as a biocompatibilizer. The lignin@HBPSi was uniformly dispersed in the PLA/PBAT matrix with improved interfacial compatibility. Dynamic rheological results revealed that the addition of lignin@HBPSi reduced the complex viscosity, improving the processing ability of the PLA/PBAT composite. The PLA/PBAT composite containing 5 wt% lignin@HBPSi had a superior toughness with an elongation at break of 300.2 % and a slight enhancement in tensile stress (34.47 MPa). In addition, the presence of lignin@HBPSi contributed to blocking ultraviolet rays in the full ultraviolet band. This work provides a feasible way to develop highly ductile PLA/PBAT/lignin composites with good UV-shielding properties for the packaging applications.

Synthesis and Characterization of Crosslinked Castor Oil-Based Polyurethane Nanocomposites Based on Novel Silane-Modified Isocyanate and Their Potential Application in Heat Insulating Coating.

An isocyanate with trimethoxysilane groups at the side chains (IPDI-M) was synthesized via an addition between the mercaptopropyl trimethoxysilane groups (MPTMS) and IPDI tripolymer (IPDI-T). Then, silane grafted isocyanate as the functional hard segment, castor oil as the soft segment, poly (ethylene adipate) diol (PEA) as the chain extender, and MPTMS as an end-capping reagent were applied to form a series of organosilicon hybrid bio-based polyurethane (CPUSi). The effect of the IPDI-M contents on the thermal stability, mechanical properties, and surface properties of the resulting product was systematically investigated. Profit from the Si-O-Si crosslinked structures formed from MPTMS curing, the tensile strength, and Young's modulus of the resulting products increased from 9.5 MPa to 22.3 Mpa and 4.05 Mpa to 81.59 Mpa, respectively, whereas the elongation at break decreased from 342% to 101%. The glass transition temperature, thermal stability, transparency, hydrophobicity, and chemical resistance were remarkably strengthened for the obtained organosilicon-modified polyurethane with the increasing MPTMS content. At the end of the work, the thermal insulation coating that was based on CPUSi and ATO can effectively block near-infrared rays, and the temperature difference between the inside and outside of the film reached 15.1 °C.

Single Molecular Layer of Chitin Sub-Nanometric Nanoribbons: One-Pot Self-Exfoliation and Crystalline Assembly into Robust, Sustainable, and Moldable Structural Materials.

Sub-nanometric materials (SNMs) represent a series of unprecedented size-/morphology-related properties applicable in theoretical research and diverse cutting-edge applications. However, in-depth investigation and wide utilization of organic SNMs are frequently hindered, owing to the complex synthesis procedures, insufficient colloidal stability, poor processability, and high cost. In this work, a low-cost, energy-efficient, convenient, effective, and scalable method is demonstrated for directly exfoliating chitin SNMs from their natural sources through a one-pot "tandem molecular intercalation" process. The resultant solution-like sample, which exhibits ribbon-like feature and contains more than 85% of the single molecular layer (thickness <0.6 nm), is capable of being solution-processed to different types of materials. Thanks to the sub-nanometric size and rich surface functional groups, chitin SNMs reveal versatile intriguing properties that rarely observe in their nano-counterparts (nanofibrils), e.g., crystallization-like assembly in the colloidal state and alcoplasticity/self-adhesiveness in the bulk aggregate state. The finding in this work not only opens a new avenue for the high value-added utilization of chitin, but also provides a new platform for both the theoretical study and practical applications of organic SNMs.

Design of a Superhydrophobic Strain Sensor with a Multilayer Structure for Human Motion Monitoring.

A flexible strain sensor is of significant importance in wearable electronics since it can help monitor the physical signals from the human body. Among various strain sensors, the polyurethane (PU)-based ones have received widespread attention owing to their excellent toughness, large working range, and nice gas permeability. However, the hydrophobicity of these sensors is not good enough, which may affect their use life and sensitivity. In this work, a high-performance strain sensor composed of PU, reduced graphene oxide (rGO), polydopamine (PDA), and 1H,1H,2H,2H-perfluorodecane-thiol (PFDT) was designed and prepared. The results revealed that this PU/rGO/PDA/PFDT device possessed good superhydrophobicity with a water contact angle of 153.3°, a wide working strain range of 590%, and an outstanding gauge factor as high as 221 simultaneously. Because of these above advantages, the sensor worked effectively in detecting both subtle and large human movements (such as joint motion, finger motion, and vocal cord vibration) even in a high humidity environment. This strain sensor with high sensitivity, wide working range, and suitable modulus may have great potential in the field of flexible and wearable electronics in the near future.

Biodegradable and renewable UV-shielding polylactide composites containing hierarchical structured POSS functionalized lignin.

The demand for biodegradable and renewable UV-shielding materials is ever increasing due to the rising concern for the environment. In this paper, biobased lignin was functionalized by polyhedral oligomeric silsesquioxane (POSS) with an epoxy substituent. Then the POSS decorated lignin (lignin-POSS) was mixed with polylactide (PLA) to act as UV-shielding filler by melt compounding. The SEM observation revealed that the presence of POSS contributed to improving the homogeneous dispersion of lignin-POSS in the PLA matrix with good compatibility when the content of lignin-POSS was lower than 5 wt%. The synergistic effects of lignin and POSS endowed PLA composite films with a good balance of UV-shielding ability and transparency in the visible light region. With the addition of 5 wt% lignin-POSS, the PLA composite film absorbed almost all UV irradiation across the entire UV spectrum. In addition, the presence of lignin-POSS could serve as a nucleating agent to increase the degree of crystallinity of PLA. The dynamical rheological tests revealed that the lignin-POSSS reduced the complex viscosity and storage modulus of PLA composites, improving the flowability of PLA composites. This work presents a viable pathway to prepare biodegradable and renewable UV-shielding materials for potential packaging applications.

Pseudosolvent Intercalator of Chitin: Self-Exfoliating into Sub-1 nm Thick Nanofibrils for Multifunctional Chitinous Materials.

Traditionally, energy-intensive and time-consuming postmechanical disintegration processes are inevitable in extracting biopolymer nanofibrils from natural materials and thereby hinder their practical applications. Herein, a new, convenient, scalable, and energy-efficient method for exfoliating nanofibrils (ChNFs) from various chitin sources via pseudosolvent-assisted intercalation process is proposed. These self-exfoliated ChNFs possess controllable thickness from 2.2 to 0.8 nm, average diameter of 4-5 nm, high aspect ratio up to 103 and customized surface chemistries. Particularly, compared with elementary nanofibrils, ChNFs with few molecular layers thick exhibit greater potential to construct high-performance structural materials, e.g., ductile nanopapers with large elongation up to 70.1% and toughness as high as 30.2 MJ m-3 , as well as soft hydrogels with typical nonlinear elasticity mimicking that of human-skin. The proposed self-exfoliation concept with unique advantages in the combination of high yield, energy efficiency, scalable productivity, less equipment requirements, and mild conditions opens up a door to extract biopolymer nanofibrils on an industrial scale. Moreover, the present modular ChNFs exfoliation will facilitate researchers to study the effect of thickness on the properties of nanofibrils and provide more insight into the structure-function relationship of biopolymer-based materials.

Adhesion loss mechanism based on carboxymethyl cellulose-filled hydrocolloid dressings in physiological wounds environment.

Adhesion loss of hydrocolloid wound dressings is ubiquitous clinical problem, which seriously reduces the therapeutic efficiency and patient experience. In order to address this problem, the clarification on adhesion loss mechanism and the development of effective alternatives of commercial hydrocolloid dressings are urgent and inevitable. Herein, adhesion loss mechanism of hydrocolloid dressings was investigated using sodium carboxymethyl cellulose (CMC)-filled hydrocolloid dressings exposing to physiological environment as model. The adhesion mechanism and contact angle tests were combined to obtain surface energy of dressings. The results indicated that the dissolution, swelling and exudation of CMC occurred successively (concentration reached 1.607 g/L after 10 h). The effused CMC led to the dramatic increase in surface energy (from 14.5-80.7 mN/m) and adhesion loss appeared. This work explored the origin of adhesion loss of hydrocolloid wound dressings and might promote the designing of hydrocolloid dressings with both excellent humidity control and sustained self-adhesiveness.

Preparation of porous antibacterial polyamide 6 (PA6) membrane with zinc oxide (ZnO) nanoparticles selectively localized at the pore walls via reactive extrusion.

Antibacterial polymer membranes have been widely used in many fields of our daily life. In this study, porous PA6 membrane with ZnO nanoparticles attaching on to the surface of inner pore walls is prepared. Firstly, SMA (styrene maleic anhydride copolymer) is used to graft onto the surface of ZnO nanoparticle in DMF (dimethylformamide). Then the pre-treated ZnO nanoparticles (ZnO-SMA) are added into SEBS (Styrene-ethylene-butylene-styrene copolymer)/PA6 (60/40 wt/wt) blends with co-continuous morphology. The effects of SMA molecular structure (molecular weight and maleic anhydride content) used for ZnO-SMA nanoparticles on their dispersion states in SEBS/PA6/ZnO-SMA nanocomposites are investigated. When SMA3 (MAH = 8 wt%, Mn = 250,000 g mol-1), which has relatively higher molecular weight and lower MAH content, is used as the pre-treating agent, ZnO-SMA3 nanoparticles tend to be dispersed at the phase interface in SEBS/PA6/ZnO-SMA nanocomposites. However, when SMA2 (MAH = 23 wt%, Mn = 110,000 g mol-1) with relatively lower molecular weight and higher MAH content is used, no ZnO-SMA2 nanoparticles locate at the interface but stay within PA6 phase. Porous PA6 membranes are obtained by selectively etching SEBS phase out with xylene. It can be found that porous PA6 membrane containing ZnO-SMA3 nanoparticles still exhibits much better antibacterial property (R = 3.76) toward S. aureus even at a very low ZnO content (0.5 wt%). This result should be ascribed to almost all the ZnO-SMA3 nanoparticles being exposed to the surface of inner pore walls of PA6 membrane. This work proposes an effective method to prepare porous polymer membrane with functional nanoparticles selectively located at the inner pore walls.

Exosomal miR-196a-1 promotes gastric cancer cell invasion and metastasis by targeting SFRP1.

Aim: To investigate the role of exosomal miRNAs on gastric cancer (GC) metastasis. Materials & methods: miRNA expression profiles of exosomes with distinct invasion potentials were analyzed using miRNA microarray and validated by quantitative real-time PCR. In vitro and in vivo experiments assessed the role of exosomal miR-196a-1 in GC's metastasis. Results: High expression level of exosomal miR-196a-1 expression was significantly associated with poor survival in GC. Exosomes that contained miR-196a-1 were secreted from high-invasive GC cells. Ectopic miR-196a-1 expression promoted invasion of low-invasive GC cells by targeting SFRP1. Conclusion: miR-196a-1 was delivered from high-invasive GC into low-invasive GC cells via exosomes and promoted metastasis to the liver in vitro and in vivo.

Preparation and Characterization of Polyurethanes with Cross-Linked Siloxane in the Side Chain by Sol-Gel Reactions.

A series of novel polyurethanes containing cross-linked siloxane in the side chain (SPU) were successfully synthesized through a sol-gel process. The SPU was composed of 0%-20% N-(n-butyl)-3-aminopropyltriethoxysilane (HDI-T) modified hexamethylene diisocynate homopolymer. The effects of HDI-T content on both the structure and properties of SPU were investigated by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), mechanical properties tests, gel content test, water contact angle measurement and water absorption test. FT-IR, XPS and XRD results confirmed the successful incorporation of HDI-T onto polyurethanes and the formation of Si-O-Si. The surface roughness and the Si content of SPU enhanced with the increase of HDI-T content. Both crystallization and melting temperature shifted to a lower point after the incorporation of HDI-T. The hydrophobicity, tensile strength, Young's modulus and pencil hardness overall increased with the increasing of HDI-T content, whereas the thermal stability and the elongation at break of SPU slightly decreased.

Effects of Poly(cyclohexanedimethylene terephthalate) on Microstructures, Crystallization Behavior and Properties of the Poly(ester ether) Elastomers.

To understand the role of molecular structure on the crystallization behavior of copolyester in thermoplastic poly(ether ester) elastomers (TPEEs), series of poly(butylene-co-1,4-cyclohexanedimethylene terephthalate) (P(BT-co-CT))-b-poly(tetramethylene glycol) (PTMG) are synthesized through molten polycondensation process. The effects of poly(cyclohexanedimethylene terephthalate) (PCT) content on the copolymer are investigated by Fourier transform infrared spectroscopy (FT-IR), ¹H and 13C nuclear magnetic resonance (NMR), gel permeation chromatographs (GPC), wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), mechanical, and visible light transmittance tests. FT-IR and NMR results confirm the incorporation of PCT onto the copolymer. WAXD and DSC indicate that the crystalline structure of the copolymers changed from α-PBT lattice to trans-PCT lattice when the molar fraction of PCT (MPCT) is above 30%, while both crystallization and melting temperatures reach the minima. An increase in MPCT led to an increase in the number sequence length of PCT, the thermal stability and the visible light transmittance of the copolymer, but to a slight decrease in tensile strength and elastic modulus.