改性木聚糖对PBAT/PLA复合材料包装性能的影响

通过硅烷偶联剂KH560对木聚糖（xylan）进行改性,采用熔融共混制备聚己二酸/对苯二甲酸丁二酯（PBAT）/聚乳酸（PLA）/xylan复合薄膜,探讨了不同含量的xylan和改性木聚糖（s-xylan）对薄膜的力学性能和透氧、透湿、透光等性能的影响。结果表明,复合薄膜的拉伸强度和氧气透过率在当s-xylan含量为1 %（质量分数,下同）时达到最佳效果,其中拉伸强度较纯PBAT/PLA薄膜提高了11.7 %,氧气透过率比纯PBAT/PLA薄膜的氧气透过系数降低了32.7 %;s?xylan复合薄膜的阻湿能力明显优于未改性xylan复合薄膜,同时复合薄膜雾度随着xylan含量的增加而增大。     

The effect of side chains on the reactive rate and surface wettability of pentablock copolymers by ATRP

The reactive rate and surface wettability of three pentablock copolymers PDMS‐b‐(PMMA‐b‐PR)₂ (R = 3FMA, 12FMA, and MPS) obtained via ATRP for coatings are discussed. Poly(dimethylsiloxane) (PDMS) is used as difunctional macroinitiator, poly(methyl methacrylate) (PMMA) as the middle block, while poly(trifluoroethyl methacrylate) (P3FMA), poly(dodecafluoroheptyl methacrylate) (P12FMA) and poly(3‐(trimethoxysilyl)propyl methacrylate) (PMPS) as the end block, respectively. Their reactive rates obtained by gas chromatography (GC) analysis indicate that 3FMA gains 8.053 × 10^?5 s^?1 reactive rate and 75% conversion, higher than 12FMA (4.417 × 10^?5 s^?1, 35%), but MPS has 1.9389 × 10^?4 s^?1 reactive rate and 96% conversion. The wettability of pentablock copolymer films is characterized by water contact angles (WCA) and hexadecane contact angles (HCA). The PDMS‐b‐(PMMA‐b‐P12FMA)₂ film behaves much higher advancing and receding WAC (120° and 116°) and HCA (60° and 56°) than PDMS‐b‐(PMMA‐b‐P3FMA)₂ film (110° and 106° for WAC, 38° and 32° for HAC) because of its fluorine‐rich surface (20.9 wt % F). However, PDMS‐b‐(PMMA‐b‐PMPS)₂ film obtains 8° hysteretic contact angle in WAC (114°–106°) and HAC (32°–24°) due to its higher surface roughness (138 nm). Therefore, the fluorine‐rich and higher roughness surface could produce the lower water and oil wettability, but silicon‐rich surface will produce lower water wettability. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40209.     

Synthesis and properties of polydimethylsiloxane/graphene oxide modified,water-based polyurethane/polyacrylate

In this study, we prepared polydimethylsiloxane–graphene oxide (PG) modified waterborne polyurethane acrylate (WPUA) films and enhanced their hydrophobicity, thermal stability, and mechanical properties. The prepared films were characterized by Fourier transform infrared and energy spectroscopy analysis; this confirmed the successful incorporation of PG into WPUA. As shown by scanning electron microscopy and atomic force microscopy analysis, the surfaces of the WPUA films were confirmed to have turned smoother and more compact after PG addition. With an optimized amount of PG (0.1%) incorporated into the WPUA film, it exhibited a contact angle improvement of 21.9°, an enhanced decomposition temperature at 5% weight losses of 25 °C, and an elongation at break improvement of 482.92% over those of pure WPUA. The newly synthesized PG–WPUA showed considerable enhancements in its hydrophobicity and thermal and mechanical properties and could be deemed to have potential value as an alternative contender for practical applications in coatings painted on tunnels and highways. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47926.     

纳米SiO2/OTAC协同稳定Pickering乳液聚合制备水基硅橡胶

以十八烷基三甲基氯化铵(OTAC)协同纳米SiO₂制备Pickering乳液,碱性条件下引发D₄开环聚合制备线性聚硅氧烷(PDMS),然后加入交联剂KH560制备阳离子型水基硅橡胶乳液。考察了纳米SiO₂与OTAC用量对Pickering乳液性能的影响,通过zeta电位、TEM及SEM研究了OTAC在SiO₂表面的吸附状态,用FT-IR、²⁹Si NMR对水基硅橡胶的结构进行了表征,研究了KH560用量对橡胶膜对水接触角和邵氏硬度的影响。结果表明: w(SiO₂)=2.0%时,乳液流动性和稳定性最优;w(OTAC) = 1.75%时,OTAC在纳米SiO₂表面的单层吸附达到饱和,单体转化率为89%,粒径为617 nm,zeta电位接近零点,PDMS的数均分子量为16036,PDI为1.485;w(KH560)=5.0%时,KH560与PDMS充分水解缩合,硅橡胶膜憎水性和硬度显著提高。     

Mechanism and properties of coloured nanoscale SiO2 prepared from silica and reactive dyes

KH560‐modified SiO₂ was prepared using tetraethyl orthosilicate (TEOS) and γ‐(2,3‐epoxypropoxy) propytrimethoxysilane (KH560) by the sol–gel method and then coloured with CI Reactive Blue 4 (X‐BR) to prepare coloured nanoscale SiO₂. The antisolvent performance and the results of cross‐polarisation/magic angle spinning ¹³C nuclear magnetic resonance and Fourier transform infrared spectroscopy showed that the reaction of X‐BR with KH560‐modified SiO₂ is a two‐step process: X‐BR is firstly adsorbed by KH560‐modified SiO₂ via van der Waals forces, and then nucleophilic substitution occurs between dichloro triazine and the epoxy group. The grafting ratio of X‐BR on KH560‐modified SiO₂ reached 95% under optimum conditions, i.e. a mass ratio of KH560 to TEOS of 20%, a temperature of 40 °C, a pH of 8.5, and a reaction time of 5 h. X‐ray diffraction analysis and transmission electron microscopy showed that the coloured nanoscale SiO₂ was amorphous, with a mean diameter of 216 nm. Experimental application showed that the coloured nanoscale SiO₂ had excellent stability to solvents and alkaline solution, and the absorptive capacity of the coloured nanoscale SiO₂ in the 200–400 nm region was higher than that of X‐BR. The light fastness of the coloured nanoscale SiO₂ reached 5–6 grade.     

不同官能度水性聚氨酯丙烯酸酯的合成及性能

以丙烯酸羟乙酯与季戊四醇三丙烯酸酯作为封端剂,分别合成了二官能度水性聚氨酯丙烯酸酯(WPUA2)和六官能度的水性聚氨酯丙烯酸酯(WPUA6),并用红外光谱、粒径仪、热重分析对合成产物结构和性能进行表征。研究表明,相比于使用低官能度WPUA2紫外光固化所得聚氨酯丙烯酸酯(PUA)涂膜,加入单体或使用多官能度WPUA6,都可使PUA固化膜凝胶率提高20%以上,吸水率降低30%;质量损失10%,分解温度增大82℃。提高预聚物官能度可有效提高涂膜交联密度和耐热性能,并具有与加入活性单体相似的应用效果。     

In-situ growth of VNb9O25 nanowires on a traditional ceramic film for high-performance lithium-sulfur batteries

Traditional ceramic films are easily wrinkled at high temperature. In addition, the ceramic films often crack when a large amount of pressure is applied. As a result, their low strength limits their application in many areas. In our work, a modified ceramic film was prepared by growing VNb₉O₂₅ nanowires (VNONW) on the surface of a pristine ceramic film (CF). The VNONW/CF was synthesized via in-situ growth by a hydrothermal method. The morphology of the VNONW was observed by using scanning electron microscopy, which indicated that the VNONW exhibited a nanowire structure. The wettability of the as-prepared VNONW/CF was investigated by testing the contact angle of VNONW/CF in the electrolyte. The as-prepared VNONW/CF could maintain a perfect shape even when the temperature was improved to 200 °C, thus demonstrating its excellent mechanical properties. In contrast, the pristine ceramic film suffered from severe deformation during the heating process. Finally, the as-prepared VNONW/CF showed superior electrochemical performance in the lithium-sulfur batteries.     

Growth and optical properties of large-scale MoS2 films with different thickness

The synthesis of large-scale molybdenum disulfide (MoS₂) with high quality is highly desirable for the promising applications in flexible optoelectronic devices. Here, we report a feasible one-step chemical vapor deposition (CVD) synthesis of continuous MoS₂ films with different layer-number via adjusting the growth temperature in the range of 740–800 °C. Influences of the annealing treatments at diverse temperature ranging from 300 to 500 °C on Raman and PL spectra of the monolayer MoS₂ film grown at 780 °C are reported. PL characterization shows that the PL emission of film annealed at 400 °C exhibits highest intensity with a blue-shift in comparison to that of the pristine film grown at 780 °C. The PL fluctuation of the MoS₂ film annealed at 400 °C is mainly originated from the high crystalline quality and strain-release. This study sheds a light on growth and performance optimization of the large-area two-dimensional transition metal dichalcogenides films.     

Preparation and properties of fluorinated silicon two‐component polyurethane hydrophobic coatings

A polyurethane (PU) hydrophobic coating was prepared by the two‐component method, polycarbonate diol and isophorone diisocyanate becoming a two‐phase composition. The PU films with hydrophobic surface were prepared by establishing a rough structure on the surface of silica (SiO₂) modified with silane coupling agents (γ‐(2,3‐epoxypropoxy)propytrimethoxysilane (KH560) and (heptadecafluoro‐1,1,2,2‐tetradecyl)trimethoxysilane (FAS)). First, the surface of SiO₂ was covered by a layer of hydrophobic methyl and fluorocarbon (C–F) groups. Then, the SiO₂ and modified SiO₂ were obtained by the introduction of KH560 and FAS with the silanol reaction by ultrasonic stirring. The effect of SiO₂ and modified SiO₂ on the structure and hydrophobic properties of PU was investigated by a series of test instruments. The results showed that the introduction of SiO₂ and modified SiO₂ was beneficial for increasing the roughness of the PU coating surface; the roughness of FAS/SiO₂‐PU could reach up to 14.790 nm, four times better than pure PU. A hydrophobic modified PU coating with water contact angle 123° was fabricated by using the hydrophobic C–F group FAS as a low surface energy material and establishing a micro rough structure on the surface of PU. Moreover, PU modified with KH560 and FAS can reduce the glass transition temperature (T_g) of soft segments, resulting in improvement of micro‐phase separation. © 2020 Society of Chemical Industry     

Study on preparation and anticorrosive performance of a new high hydrophobic anticorrosive coating

Water-based anticorrosive coatings have poor water resistance, which easily lead to coating deterioration and metal corrosion. In order to improve the anticorrosion performance of waterborne coating, herein, the polytetrafluoroethylene/dimethyl siloxane/epoxy resin (PTFE/PDMS/EP) hydrophobic anticorrosive coating was prepared by layer-by-layer construction. The spatial structure and microscopic morphology of the hydrophobic coating were analyzed by XRD, FTIR, and SEM. The hydrophobicity and corrosion resistance of the composite coating were analyzed by hydrophobicity test, electrochemical polarization curve, hydrophobicity and corrosion resistance test of the mixed layer, Tafel polarization curves, and AC impedance spectrum. The results showed that the water contact angle of PTFE/PDMS/EP coating reached 141° and the protection efficiency of PTFE/PDMS/EP coating was 98.62%. After soaking for 7 days, the corrosion process still stays at the initial stage, which was mainly due to the good sealing and barrier properties and high anticorrosion efficiency of PTFE/PDMS/EP coating. The coating has high corrosion protection efficiency and long service life, which is of great significance to metal corrosion protection in harsh marine environments.     

2D MoS2 Nanosheet-Based Polyimide Nanocomposite with High Energy Density for High Temperature Capacitor Applications

With the development of electrical vehicles and power electronics, the demand for high-temperature energy storage capacitors with high energy density has grown rapidly. In this investigation, 2D MoS₂ nanosheets are coated with a thin layer of poly(methyl methacrylate) and then mixed with polyimide (PI) solution to fabricate nanocomposites. The dielectric constant of MoS₂-g-PMMA/PI (MPP-3%) reaches 4.2, which is 20% higher than that of a pristine PI film. The energy density of the MPP-3% nanocomposite reaches 8.6 J cm⁻³, which is 40% higher than the highest energy density of a pristine PI film. In addition, the electric breakdown field of the MPP-3% composite is 50% higher than that of the MoS₂/PI nanocomposite without a surface coating. Furthermore, it is found that the highest energy density of MoS₂-g-PMMA/PI reaches 3.92 J cm⁻³, which is 47.9% higher than that of the PI film at 150 °C. The charge–discharge efficiency of the nanocomposite film reaches 61.7% at 150 °C. This result is much higher than the previously reported research results for high-temperature capacitor applications. The MoS₂-g-PMMA/PI-based nanocomposite shows great promise for use in high-temperature capacitor applications.     

Multifunctional MXene/CNT-based layered film for icing detection,anti-icing,and deicing application

Icing phenomenon usually happens in our daily life, especially in the cold winter or in high altitude areas, which makes us feel inconvenient and greatly threats some fields such as civil aviation or the manufacturing industry. In this study, a multifunctional film with properties of icing detection, anti-icing and deicing was fabricated. One-dimensional material carbon nanotube (CNT) and two-dimensional material Ti₃C₂T_x MXene were combined by two-step vacuum filtration. Polydimethylsiloxane (PDMS) as the flexible hydrophobic materials was then used to encapsulate layered film. Additionally, PDMS curing process on the sandpaper could make the surface of MXene/CNT layered film possess micro-structures. The low surface energy material PDMS and rough surface structures endow MXene/CNT layered film with good water-repellency. Compared with pure PDMS film (103°), the contact angle of MXene/CNT layered film surface reaches 128°. The result exhibits that a waterdrop(100uL) on the layered film surface takes 1425s to be frozen, which takes longer time than glass and pure PDMS. Additionally, excellent sensibility of the layered film could be used to detect icing phenomenon. The result manifests that gauge factor (GF) of MXene/CNT film reaches 15051 so that different icing stages could be identified by layered film clearly. MXene/CNT layered film possesses good electric heating and photo-thermal properties. The result shows that surface temperature can reach 89 °C with the 2.5 V voltage supply, and temperature reaches 95 °C through the radiation of near-infrared lamp as well. The dual-driven heating of MXene/CNT layered film shows the ability of deicing. 1000 mg ice just takes 223s to be melted entirely by 2.5 V input voltage, and 269s by radiation of 200 mW/cm², respectively. The multifunctional MXene/CNT based layered film prepared by a simple fabrication method that integrates hydrophobicity, dual-driven heating, and sensibility together, which shows potential application in icing detection, anti-icing, and deicing.     

Hydrophobic stretchable polydimethylsiloxane films with wrinkle patterns prepared via a metal-assisted chemical etching process using a Si master mold

We fabricated hydrophobic, stretchable, wrinkle-patterned polydimethylsiloxane (PDMS) films via a metal-assisted chemical etching (MACE) process using a Si master mold, which is a mask-free technique for fabricating large-area films. The wrinkle-patterned PDMS surface prepared via MACE exhibited high hydrophobicity and stretchability, which are difficult to achieve with wrinkle-patterned PDMS prepared via a conventional process, such as, plasma treatment, e-beam, or laser patterning. The contact angle of the wrinkled PDMS surface was dependent on the size of the micro/nanostructures, and the largest contact angle was 135.8 ± 0.1° for the film prepared under the optimum conditions. To confirm the applicability of the wrinkled PDMS films to flexible electronics, we tuned the mechanical properties by controlling the crosslinker ratio in the films. The Young's modulus ranged from 0.193 to 1.364 MPa depending on the crosslinker ratio, and the stress of the optimum film was 1.5 MPa under 250% strain.     

PDMS乳液/硅溶胶杂化水分散体系及其复合膜的制备与表征

以聚硅氧烷(PDMS)乳液/硅溶胶杂化水分散液为成膜基质,硅烷偶联剂KH 550为固化剂,制备了双组分水基有机硅涂料;将其固化后得到PDMS/硅溶胶复合膜。通过水分散液的粒径分布及红外光谱分析,研究了水分散液的脱水成膜过程;采用扫描电镜(SEM)和原子力显微镜(AFM)对复合膜的断面和表面形态进行了表征。结果表明:PDMS乳液加入硅溶胶后,粒径分布变宽,粒径略有增加;成膜后,硅溶胶粒子与PDMS长链发生了相互作用,并作为分散相被包埋在PDMS中;复合膜表面形成簇状结构,表面粗糙度随着硅溶胶含量的增加而增加。当硅溶胶与PDMS乳液的固体质量比由10%增加到30%时,复合膜的拉伸强度由0.76MPa升高到3.10MPa,而拉断伸长率从680%下降到470%。     

Bilaterally Microstructured Thin Polydimethylsiloxane Film Production

Thin PDMS films with complex microstructures are used in the manufacturing of dielectric electro active polymer (DEAP) actuators, sensors and generators, to protect the metal electrode from large strains and to assure controlled actuation. The current manufacturing process at Danfoss Polypower A/S produces films with a one-sided microstructured surface only. It would be advantageous to produce a film with both surfaces microstructured, as this increases the film’s performance efficiency. The new technique introduced herein produces bilaterally microstructured film by combining an embossing method with the existing manufacturing process. In employing the new technique, films with microstructures on both surfaces are successfully made with two different liquid silicone rubber (LSR) formulations: 1) pure XLR630 and 2) XLR630 with titanium dioxide (TiO₂). The LSR films (～70 µm) are cast on a carrier web substrate using a coating blade. The carrier web, which has a sinusoidal corrugation with wave height of 7 µm and a wave period of 7 µm on its surface, imparts corrugations to the bottom surface of the film. The elastomer film on the carrier web is preheated to the gel point, where the elastomer film can retain an imprint made on it. The preheated film at gel point is embossed between the rolls of a gravure lab coater, which corrugates the top surface of the film. The films are then heated, in order to cure completely. For the LSR systems used in this process, the optimum conditions for preheating are 110°C for 4–7 s, while for embossing the temperature is 110°C with 25 psi pressure between the rolls at a speed of 1.4 rpm. Scanning electron microscope (SEM) images confirm the formation of microstructures on both the surfaces of the film.     

Biodegradable,superhydrophobic walnut wood membrane for the separation of oil/water mixtures

The preparation of environmentally friendly oil/water separation materials remains a great challenge. Freeze-drying of wood after lignin removal yields wood aerogels, which can be used as substrates to prepare fluorine-free environmentally friendly superhydrophobic materials, However, they are more suitable for absorption rather than filtration applications due to their poor strength. A study using cross-sections of pristine wood chips as substrates retains the original strength of wood, but the use of the cross-sectional of wood pieces limits their thickness, strength, and size. In this paper, a degradable fluorine-free superhydrophobic film (max. water contact angle of approximately 164.2°) with self-cleaning and abrasion resistance characteristics was prepared by a one-step method using pristine and activated walnut longitudinal section films as the substrate, with tetraethyl orthosilicate as a precursor and dodecyltriethoxysilane as a modifier. The tensile strength results show that superhydrophobic films with pristine or activated wood substrates maintained the strength of pristine wood and were 2.2 times stronger than the wood aerogel substrate. In addition, after cross-laminating the two samples, the films had the ability to separate oil and water by continuous filtration with high efficiency (98.5%) and flux (approximately 1.3 × 10³ L∙m^‒2∙h^‒1). The method has potential for the large-scale fabrication of degradable superhydrophobic filtration separation membranes.     

Grafting of Epoxy Resin on Surface-modified Poly(tetrafluoroethylene) Films

An epoxy/PTFE composite was prepared by curing the epoxy resin on the surface-modified PTFE film. Surface modification of PTFE films was carried out via argon plasma pretreatment, followed by UV-induced graft copolymerization with glycidyl methacrylate (GMA). The film composite achieved a 90°-peel adhesion strength above 15 N/cm. The strong adhesion of the epoxy resin to PTFE arose from the fact that the epoxide groups of the grafted GMA chains were cured into the epoxy resin matrix to give rise to a highly crosslinked interphase, as well as the fact that the GMA chains were covalently tethered on the PTFE film surface. Delamination of the composite resulted in cohesive failure inside the PTFE film and gave rise to an epoxy resin surface with a covalently-adhered fluoropolymer layer. The surface composition and microstructures of the GMA graft-copolymerized PTFE (GMA-g-PTFE) films and those of the delaminated epoxy resin and PTFE film surfaces were characterized by X-ray photoelectron spectroscopy (XPS), water contact angle and scanning electron microscope (SEM) measurements. The delaminated epoxy resin surfaces were highly hydrophobic, having water contact angles of about 140°C. The value is higher than that of the pristine PTFE film surface of about 110°. The epoxy resin samples obtained from delamination of the epoxy/GMA-g-PTFE composites showed a lower rate of moisture sorption. All the fluorinated epoxy resin surfaces exhibited rather good stability when subjected to the Level 1 hydrothermal reliability tests.     

Post Curing as an Effective Means of Ensuring the Long-term Reliability of PDMS Thin Films for Dielectric Elastomer Applications

Post curing can be used to facilitate volatile removal and thus produce polydimethylsiloxane (PDMS) films with stable elastic and electrical properties over time. In this study, the effect of post curing was investigated for commercial silicone elastomer thin films as a means of improving long-term elastomer film reliability. The Young’s moduli and electrical breakdown strengths of commercial (silica-reinforced) PDMS elastomer films, with and without additional 35 parts per hundred rubber titanium dioxide (TiO₂), were investigated after high-temperature (200°C) post curing for various time spans. The elastomers were found to contain less than 2% of volatiles (significantly higher for TiO₂-filled samples), but nevertheless a strong effect from post curing was observed. The young’s moduli as well as the strain-dependent behavior were found to change significantly upon post curing treatment, where Young’s moduli at 5% strain increase with post curing. Furthermore, the determined dielectric breakdown parameters from Weibull analyses showed that greater electrical stability and reliability could be achieved by post curing the PDMS films before usage, and this method therefore paves a way toward more reliable dielectric elastomers.     

Influence of Mesoporous Silica and Butyral Content on the Mechanical,Water Absorption,and Permeability Properties of in situ Synthesized Silica/PVB Nanocomposite Films

Poly(vinyl butyral)–silica nanocomposites were synthesized in situ with three different degrees of butyral and with varying silica content for each vinyl butyral polymer ratio. The glass transition temperatures of the polymer nanocomposites were found to be ～40–46 and ～52°C for the neat polymer, respectively. The 4 wt% silica loaded film showed higher strength and lower strain to failure compared with the neat polymer. The matrix with 0.5 and 0.75 butyral:alcohol for 2.5–4 wt% silica exhibited good water vapor transmission and the efficiencies of these films were 50% higher than their encapsulated pristine polymer films.     

Enhanced electrochemical properties of fluoride-coated LiCoO<Subscript>2</Subscript> thin films

The electrochemical properties of fluoride-coated lithium cobalt oxide [LiCoO₂] thin films were characterized. Aluminum fluoride [AlF₃] and lanthanum fluoride [LaF₃] coating layers were fabricated on a pristine LiCoO₂ thin film by using a spin-coating process. The AlF₃- and LaF₃-coated films exhibited a higher rate capability, cyclic performance, and stability at high temperature than the pristine film. This indicates that the AlF₃ and LaF₃ layers effectively protected the surface of the pristine LiCoO₂ film from the reactive electrolyte.