超级柔韧性和优异电磁屏蔽性能的PVA-co-PE纳米纤维覆铜膜

本工作通过紫外辐射诱导和化学还原反应相结合成功制备了具有多级结构的聚乙烯醇-聚乙烯(PVA-co-PE)纳米纤维覆铜膜,PVA-co-PE纳米纤维覆铜膜具有超级柔韧性能和电磁屏蔽性能,且具有多次循环压缩后性能不减的稳定性。首先通过紫外辐照引入一定量的活化羟基,然后通过静电配位和铜粒子的化学还原作用,在纳米纤维膜上实现无钯镀铜。采用傅里叶红外光谱仪(AIR-FTIR)、能量色散型X射线荧光分析仪(EDX-7000)、扫描电子显微镜(SEM)等对样品进行结构性能分析。结果表明,成功实现PVA-co-PE纳米纤维覆铜膜的制备,SEM图表明,铜颗粒均匀分布于纳米纤维膜表面,并且薄膜由亲水转变为不易浸润。通过四探针仪器和矢量网络分析仪表征了薄膜材料的导电性和电磁屏蔽性能。结果表明,覆铜膜达到导体水平,吸波值达到47.3 dB。经过多次循环压缩后覆铜膜材料电磁屏蔽性能几乎不减,说明制得的纳米纤维覆铜膜具有优异的柔韧性和吸波稳定性,其在柔性智能可穿戴元器件领域具有广阔的应用空间。

MXene@c-MWCNT Adhesive Silica Nanofiber Membranes Enhancing Electromagnetic Interference Shielding and Thermal Insulation Performance in Extreme Environments

A lightweight flexible thermally stable composite is fabricated by com-bining silica nanofiber membranes(SNM)with MXene@c-MWCNT hybrid film.The flexible SNM with outstanding thermal insulation are prepared from tetraethyl orthosilicate hydrolysis and condensation by electrospinning and high-temperature calcination;the MXene@c-MWCNT_(x:y)films are prepared by vacuum filtration tech-nology.In particular,the SNM and MXene@c-MWCNT_(6:4)as one unit layer(SMC_(1))are bonded together with 5 wt%polyvinyl alcohol(PVA)solution,which exhibits low thermal conductivity(0.066 W m^(-1)K^(-1))and good electromagnetic interference(EMI)shielding performance(average EMI SE_(T),37.8 dB).With the increase in func-tional unit layer,the overall thermal insulation performance of the whole composite film(SMC_(x))remains stable,and EMI shielding performance is greatly improved,especially for SMC_(3)with three unit layers,the average EMI SET is as high as 55.4 dB.In addition,the organic combination of rigid SNM and tough MXene@c-MWCNT_(6:4)makes SMC_(x)exhibit good mechanical tensile strength.Importantly,SMC_(x)exhibit stable EMI shielding and excellent thermal insulation even in extreme heat and cold environment.Therefore,this work provides a novel design idea and important reference value for EMI shielding and thermal insulation components used in extreme environmental protection equipment in the future.

Polymer-free electrospun separator film comprising silica nanofibers and alumina nanoparticles for Li-ion full cell

A separator film for high-performance Li-ion batteries was prepared by electrospinning. The film had a hybrid morphology of silica nanofibers(SNFs) and alumina nanoparticles(ANPs), with a smooth surface, polymer-free composition, high porosity(79%), high electrolyte uptake(876%), and excellent thermal stability. Contact angle measurements demonstrated the better immersion capability of the SNF-ANP separator film for commercial liquid electrolytes than a commercial CELGARD 2500 separator film. Moreover,compared to the commercial CELGARD 2500 separator, the ionic conductivity of the SNF-ANP separator film was nearly three times higher, the bulk resistance was lower at elevated temperature(120 ℃), the interfacial resistance with lithium metal was lower, and the electrochemical window was wider. Full cells were fabricated to determine the cell performance at room temperature. The specific capacity of the full cell with the SNF-ANP separator film was 165 mAh g-1;the cell was stable for 100 charge/discharge cycles and exhibited a capacity retention of 99.9%. Notably, the electrospun SNF-ANP separator film can be safely used in Li-ion or Li-S rechargeable batteries.

Preparation and Characterization of Co_(3)O_(4)/Graphene/Cellulose Nanofiber Composite Films

Nanocellulose has served as an eye-catching nanomaterial for constructing advanced functional devices with renewability,light weight,flexibility,and environmental friendliness.In this study,Co_(3)O_(4)/graphene/cellulose nanofiber(CNF)flexible composite films,in which the CNF acted as a spacer for the graphene,were prepared via a facile and scalable vacuum filtration method.The effects of the CNF on the microstructure,hydrophilicity,thermal stability,tensile strength,surface resistance,and electrochemical performance of the Co_(3)O_(4)/graphene/CNF composite films were systematically investigated.The results showed that the synergistic interaction of the CNF and graphene substantially improved the overall properties of the Co_(3)O_(4)/graphene/CNF composite films,particularly their hydrophilicity and tensile strength.Meanwhile,Co_(3)O_(4)/graphene/CNF composite films with a CNF content of 4%appeared to have the optimal electrochemical performance,with an area specific capacitance of 56 mF/cm^(2) and prominent capacitance retention of 95.6%at a current density of 1 A/g after 1000 cycles.This work demonstrated that the prepared Co_(3)O_(4)/graphene/CNF flexible composite films have great application potential in the field of flexible energy storage devices.

高柔性PVA-co-PE纳米纤维基复合导电透明膜的制备及性能研究

将具有独特叠层结构的聚乙烯醇-聚乙烯共聚物纳米纤维膜材料与环氧树脂复合,并引入紫外光吸收剂2,4-二羟基二苯甲酮,利用多相之间的强界面相互作用,制备得到了具有高柔韧性、高透明度和高紫外光过滤效果的复合透明膜.在该柔性基底上,通过压力转移法相继复合银纳米线层和还原氧化石墨烯层,形成了相互渗透的导电网络.最终得到面电阻为147Ω/Sq、可见光透过率约80%、紫外吸收率达90%的透明导电复合膜.该导电复合膜显示出良好的拉伸和弯曲性能,并在循环弯曲变形测试下保持良好的电学稳定性.

Production of chitosan-based composite film reinforced with lignin-rich lignocellulose nanofibers from rice husk

Lignocellulosic nanofibers(LCNFs),implying lignin-containing cellulose fibers,maintain the prop-erties of both lignin and cellulose,which are hydrophobic and hydrophilic,respectively.The pres-ence of hydrophobic lignin in LCNFs is expected to be an economical and attractive option that can improve the thermal and mechanical properties of polymers.Thus,this study was conducted to produce lignin-rich LCNFs from sugar-rich waste obtained from rice husks after acidic pretreat-ment.The LCNFs were produced from the lignin-rich solid fractions obtained after pretreatment and enzymatic hydrolysis,which were then incorporated as an additive into a chitosan-based film.The variations in lignin content in the range of approximately 50.6%-66.8%in differently obtained LCNFs gave significantly different optical strengths and mechanical properties.These controllable processes may allow for customized film formation.Additionally,the glucose-rich liquid fractions obtained after pretreatment and enzymatic hydrolysis were used as a substrate for ethanol fermentation to achieve total utilization of rice husk biomass waste.In conclusion,the lignin-rich biomass fraction holds promise as a suitable material for chitosan-LCNF film and has the potential to increase the economic feasibility of the biomaterial industry.

Ultra-low reflection electromagnetic interference shielding nanofiber film with effective solar harvesting and self-cleaning

It is urgent to develop low-reflection electromagnetic interference shielding material to shield electromagnetic waves(EMW)and reduce their secondary radiation pollution.Herein,an electromagnetic interference shielding nanofiber film is composed of ZnO and carbon nanofiber(CNF)via electrospinning and carbonization approachs,and subsequently coating perfuorooctyltriethoxysilane as a protective layer.On the one hand,ZnO coated by porous carbon,which is derived from ZIF-8,endows the nanofiber film low reflection property through optimizing impedance matching between free space and the nanofiber film.On the other hand,the nanofiber film possesses high electromagnetic interference shielding efficiency,which is beneficial by excellent electrical conductivity of CNF derived from waste leather scraps.Furthermore,the nanofiber film involves abundant interface,which contributes to high interfacial polarization loss.Thus,the nanofiber film with a thickness of 250 pm has electrical conductivity of 53 S/m and shielding efficiency of 50 dB.The reflection coefficient of the nanofiber film is inferior to 0.4 indicates that most of EMW are absorbed inside the materials and the nanofiber film is effective in reducing secondary radiation contamination of electromagnetic waves.Fortunately,the nanofiber film exhibits outstanding solar harvesting performance(106℃at 1 sun density)and good self-cleaning performance,which ensure that the nanofiber film can work in harsh environments.This work supplies a credible reference for fabricating low-reflection electromagnetic shielding nanofiber film to reduce secondary radiation pollution and facilitates the upcycling of waste leather scraps.

Nanofibrillation of Bacterial Cellulose Using High-Pressure Homogenization and Its Films Characteristics

The microstructure of bacterial cellulose nanofibers(BCNs)film affects its characteristic.One of several means to engineer the microstructure is by changing the BCNs size and fiber distribution through a high-pressure homogenizer(HPH)process.This research aimed to find out the effects of repetition cycles on HPH process towards BCNs film characteristics.To prepare BCNs films,a pellicle from the fermentation of pineapple peels waste with Acetobacter xylinum(A.xylinum)was extracted,followed by crushing the pellicle with a high-speed blender,thereafter,homogenized using HPH at 150 bar pressure with variations of 5,10,15,and 20 cycles.The BCNs films were then formed through the casting process and drying in the oven at 60°C for 8 h followed by structural,morphological,and optical properties investigation using X-ray diffraction(XRD),scanning electron microscopy(SEM)and Fourier transform infrared(FTIR)spectrometer along with BCNs films porosity,tensile and roughness test.The research showed that the effect of HPH cycle on BCNs resulted in the highest film tensile strength by 109.15 MPa with the lowest surface roughness(Ra)of 0.93±0.10μm at 10 cycles.The HPH process is effective in controlling BCNs film porosity level.The HPH cycles influence the crystalline index and crystallite size,slightly.

用于压电传感器的层加层结构纳米纤维膜

通过聚丙烯腈(PAN)与改性木质素(CEHL-PTMG)接枝物进行共混,使用多层静电纺丝技术得到PAN|PAN/CEHL-PTMG|PAN层加层结构的纳米纤维膜,并制备一系列的薄膜。对制备的层加层结构纳米纤维膜进行表面形貌、构象、热性能、力学性能以及压电性能测试。实验结果表明:层加层结构使得薄膜的压电性能得到了大幅提高,PAN(11%,1 mL)|PAN/CEHL-PTMG(11%/2%,2 mL)|PAN(11%,1 mL)层加层结构纳米纤维膜的压电性能最为优异,输出电压和电流分别可达2.57 V、1468.0 nA;层加层结构薄膜的拉伸强度提高到了7.16 MPa,相较复合纳米纤维膜拉伸强度提高了7.51%,比纯PAN薄膜拉伸强度提高了52.67%;结构化后的薄膜的稳定性大幅提高,经过上千次的撞击仍能输出较好的电压;同时将其附于手指及手肘上,能更加明确地指示两者的运动,且在数值上出现较大的差距。

柔性薄膜复合形状记忆合金弹簧驱动器

针对形状记忆合金(shape memory alloy,简称SMA)材料在使用过程中因其较低的响应频率而很难应用于高频率场所问题,在聚偏氟乙烯(polyvinylidene fluoride,简称PVDF)薄膜中引入锆酸铅钡(Pb_(0.8)Ba_(0.2)ZrO_(3),简称PBZ)纳米陶瓷纤维制备柔性薄膜,并与NiTi合金弹簧复合制得PBZ/PVDF@SMA复合驱动器,通过薄膜的电卡效应加热及冷却SMA丝,与传统电流加热及自然冷却方式进行了对比。结果表明,缩短了SMA丝循环周期,提高了其响应频率,有利于扩大SMA的适用场所。

小分子增塑剂对甲壳素/百里香精油复合膜性能的影响

为了提高天然聚合物/植物精油复合膜的基础性能,以甲壳素纳米纤维(ChNFs)为基体,通过Pickering乳化法负载百里香精油(TEO)制备复合包装膜,研究小分子增塑剂甘油和液体石蜡对复合膜机械性能、光学性能的影响。结果表明,甘油和液体石蜡添加量均为0.5 wt%时会将复合膜的拉伸强度提高至14 MPa,此时最大断裂伸长率为46%。甘油和液体石蜡的添加还会提高复合膜的遮光性能和热稳定性。试验制备的高性能甲壳素/百里香精油复合膜可为多糖/植物精油复合膜进一步在食品包装方面的应用提供理论基础。

多功能Ag/PAN珍珠纳米纤维膜的制备与研究

采用静电纺丝法和磁控溅射技术两步法制备了多功能银/聚丙烯腈(Ag/PAN)珍珠纳米纤维膜,探讨了不同溅射时间对Ag/PAN珍珠纳米纤维膜微观形貌、化学结构、表面润湿性能、导电性能和远红外发射性能的影响。结果表明:随着溅射时间的增加,银颗粒尺寸逐渐增大,当溅射时间为25 min时,纳米银薄膜表现出粗糙性和致密性;经过磁控溅射后,PAN珍珠纳米纤维膜由亲水性转变为疏水性,导电性能明显改善,溅射时间增加至25 min时,纤维膜的水接触角和电阻率分别为142.85°和0.039Ω·cm;Ag/PAN珍珠纳米纤维膜不仅具有远红外发射性能,而且在纳米银薄膜的作用下还能避免辐射热量的散失,达到蓄热保温的功能。

Enhanced energy density in polyetherimide nanocomposite film at high temperature induced by electrospun BaZrTiO_(3) nanofibers

Polymer dielectrics which possess excellent dielectric properties such as high breakdown strength,flexibility,and facile processability are considered as promising materials for advanced electrostatic capacitors.However,most dielectric polymers have unsatisfactory energy storage performances at high-temperature environments.Here,polyetherimide(PEI) nanocomposite films contained with electrospun Ba(Zr_(0.79)Ti_(0.21))O_(3) nanofibers(BZTNFs) are fabricated by common solution casting method.The dielectric properties,especially the breakdown strength of the BZTNFs/PEI nanocomposites,are characterized,yet improvement is only in the small loading ones.The energy storage performance of the 0.5 vol% and1.0 vol% BZTNFs content nanocomposite is further investigated from 25 to 150℃.With the introduction of small loading BZTNFs,the dielectric permittivity and electric displacement of the nanocomposite are improved at all evaluated temperatures.The 1.0 vol% BZTNFs/PEI possesses a maximal discharged energy density of6.05 J·cm^(-3) with high efficiency of 94.9% at 25℃,then falls to 3.34 J·cm^(-3) with efficiency of 54.6% at 150℃ for the larger remnant displacement.Apparently,the relaxation ferroelectric nanofller of BZTNFs is much effective in increasing the dielectric permittivity of nanocomposite,but its capacity to restrict the migration of the charge carriers at high temperatures is weaker than that of the nanofillers with wider bandgap.The complementation of both kinds of the nanofillers probably provides an approach to available high-temperature dielectric films.

花青素—淀粉智能指示膜的制备及性能研究

以淀粉为原料,花青素为功能性物质,采用静电纺丝法制备了淀粉纳米纤维智能指示膜,并研究其结构和性能。结果表明:花青素负载量的增加会增大纤维直径和指示膜的水接触角。指示膜的晶态决定其力学性能,花青素添加到10%以上时指示膜结晶度较高其断裂应力也随之升高,达到了12.0 MPa,但断裂伸长率减小到了5.8%。加入花青素的指示膜热稳定性有所提升。静电纺丝过程不会改变淀粉和花青素的分子结构,指示膜的指示功能主要是通过花青素中酚羟基的电离状态改变引起颜色变化实现,抗氧化功能是酚羟基提供的还原性赋予的。这些结果证明了淀粉花青素智能指示膜具有良好的指示性,可用于监测食品品质变化。

Flexible and free-standing La_(0.33)Ti_(2)(PO_(4))_(3)/C nanofibers film as a novel high-performance anode for sodium-and potassium-ion batteries

Na superionic conductor(NASICON)-type La_(0.33)Ti_(2)(PO_(4))_(3)(LaTP) is firstly proposed as sodium/potassium storage materials.The density functional theory(DFT) calculations show that LaTP has good electronic character and low Na^(+)/K^(+)migration barriers.The flexible La_(0.33)Ti_(2)(PO_(4))_(3)/C nanofiber film is synthesized via electrostatic spinning and investigated as free-standing electrode applied to sodium-ion batteries(SIBs) and potassiumion batteries(PIBs) in this work.The low band gap and Na^(+)/K^(+) migration barriers of LaTP,unique morphology,and complete conductive carbon net allow the La_(0.33)Ti_(2)(PO_(4))_(3)/C nanofibers film to deliver high capacity(296.3 mAh·g^(-1) for SIBs and 235.8 mAh·g^(-1) for PIBs),excellent rate performance(142.5 mAh·g^(-1) for SIBs and50.5 mAh·g^(-1) for PIBs at 1.00 A·g^(-1)),and superior cyclability above 1000 cycles.The full-cell tests show that the material has a good application prospect,indicating a promising flexible anode material for SIBs and PIBs.

超亲水CNC/PAN复合纳米纤维膜及性能研究

以浓硫酸水解脱脂棉获得的,具有较高机械强度和结晶度的纤维素纳米晶(CNC)作为增强相,结合具有良好热稳定性、化学稳定性的聚丙烯腈(PAN),采用简单的静电纺丝技术制备了具有较高的孔隙率和纯水渗透通量的CNC/PAN复合纳米纤维膜。通过各项表征考察了CNC添加量对薄膜各项性能的影响,结果表明与Pure PAN相比,CNC/PAN复合纳米纤维膜具有良好的热稳定性,更好的力学性能和亲水性。探究了薄膜使用前后厚度、孔隙率与纯水渗透通量的变化情况,分析了薄膜的油水分离性能,拓展了其在水处理领域的应用。

羊毛角蛋白/聚乙烯醇纳米纤维膜的制备及其性能

从废旧羊毛中提取羊毛角蛋白对于资源再利用具有重要意义。针对羊毛角蛋白分子量低,难以直接纺丝等问题,将羊毛角蛋白与聚乙烯醇共混制备纺丝液,最后通过静电纺丝制备羊毛角蛋白/聚乙烯醇纳米纤维膜。利用旋转流变仪对羊毛角蛋白/聚乙烯醇纺丝液的黏度进行了分析,利用扫描电镜对羊毛角蛋白/聚乙烯醇纳米纤维的微观形貌进行了表征,采用数字源表对其传感性能进行了测试。结果表明:当聚乙烯醇与羊毛角蛋白的质量比为7∶3时,纺丝黏度适中,获得的纳米纤维粗细均匀,直径约240 nm。羊毛角蛋白/聚乙烯醇纳米纤维膜在手指弯曲运动时产生2.1 V输出电压,可感知人体生理信号,有望应用于柔性传感领域。

PVA/CNF@CuS近红外隔热膜的制备及性能

将具有近红外吸收能力的硫化铜(CuS)负载在具有高强度的纳米纤维素(CNF)上,得到CNF@CuS复合物,然后将CNF@CuS添加到聚乙烯醇(PVA)基体中,制备高强度和良好隔热性能于一体的PVA/CNF@CuS近红外隔热膜。通过扫描电镜、X射线衍射仪、傅里叶变换红外光谱仪、紫外-可见光谱仪、拉伸性能测试及隔热性能测试等对其进行结构表征及性能测试。结果表明:CNF@CuS与PVA基体具有良好的界面相容性,CNF@CuS与PVA的质量比为2∶100时,复合膜的拉伸强度由纯PVA的34.5 MPa增加到72.9 MPa,同时复合膜可以透过大部分可见光并对近红外光具有良好的屏蔽效果,且具有良好的隔热性能。

医用聚氨酯敷料研究进展

医用聚氨酯材料具有细胞毒性低、生物相容性好、力学性能优异等特性,已经成为药物、抗菌剂、抗炎剂等的良好载体。然而,传统的聚氨酯材料对石油资源的依赖程度较高,合成路线不利于绿色可持续发展。聚氨酯材料由于缺乏固有的抗菌活性和适宜的湿润性,在伤口敷料的应用中容易出现伤口感染、伤口过度润湿等问题。此外,多数研究者对伤口敷料作用效果的评估局限于小型动物模型(小鼠、兔子等),对该材料性能的研究不够深入。主要围绕医用聚氨酯材料在创面敷料方面的发展现状和问题进行了讨论与总结,并针对不同形态的聚氨酯如纳米纤维、薄膜、水凝胶、海绵及泡沫等展开了分析。提出了关于医用聚氨酯敷料的多个发展方向,包括生物质聚氨酯、多功能性聚氨酯、双层结构敷料等,期望为聚氨酯材料在医学领域中的发展提供理论依据。

功能化纳米纤维素复合PLA/PBAT薄膜的制备及性能

以γ-氨丙基三乙氧基硅烷(KH550)为改性剂对纤维素纳米纤维(CNF)进行功能化改性,并用聚丙二醇(PPG)对改性后的CNF进行包覆,制备了CNF-PPG纳米粒子。将其作为填料加到聚乳酸(PLA)/聚己二酸/对苯二甲酸丁二醇酯(PBAT)聚合物基体中,用溶液浇铸法制备了PLA/PBAT/CNF-PPG复合薄膜。通过FTIR、XPS、SEM、DSC、TG对薄膜进行了表征,探讨了PLA与PBAT的质量比及CNF-PPG纳米粒子的添加量对复合薄膜机械强度、热稳定性、阻隔性能的影响。结果表明,PLA/PBAT薄膜比纯PLA薄膜具有更高的韧性和热稳定性;当m(PLA)∶m(PBAT)=90∶10、CNF-PPG纳米粒子用量(以PLA和PBAT的质量为基准,下同)为10%时,PLA/PBAT/CNF-PPG(90/10/10)复合薄膜的拉伸强度达到(33.38±0.64)MPa,断裂伸长率为39.97%±0.67%;复合薄膜最终降解温度从纯PLA膜的394℃提高到435℃;复合薄膜的水蒸气和氧气透过系数分别为4.98×10^(–14)g·cm/(cm^(2)·s·Pa)和8.86×10^(−14)cm^(3)·cm/(cm^(2)·s·Pa),与纯PLA膜相比,分别降低了33.6%和23.5%。