查找使用阿拉丁产品的科研文献

A skin-inspired biomimetic strategy to fabricate cellulose enhanced antibacterial hydrogels as strain sensors

Junyu Jian,Yitong Xie,Shishuai Gao,Yu Sun,Chenhuan Lai,Jifu Wang,Chunpeng Wang,Fuxiang Chu,Daihui Zhang

With the development of wearable devices, the fabrication of strong, tough, antibacterial, and conductive hydrogels for sensor applications is necessary but remains challenging. Here, a skin-inspired biomimetic strategy integrated with in-situ reduction has been proposed. The self-assembly of cellulose to generate a cellulose skeleton was essential to realize the biomimetic structural design. Furthermore, in-situ generation of silver nanoparticles on the skeleton was easily achieved by a heating process. This process not only offered the excellent antibacterial property to hydrogels, but also improved the mechanical properties of hydrogels due to the elimination of negative effect of silver nanoparticles aggregation. The highest tensile strength and toughness could reach 2.0 MPa and 11.95 MJ/m 3 , respectively. Moreover, a high detection range (up to 1300%) and sensitivity (gauge factor = 4.4) was observed as the strain sensors. This study provides a new horizon to fabricate strong, tough and functional hydrogels for various applications in the future.

Insight into different roles of chitin nanocrystals and cellulose nanocrystals towards stabilizing Pickering emulsions

Guangni Peng,Defeng Wu

Rod-like polysaccharide particles such as chitin nanocrystals (ChNCs) and cellulose nanocrystals (CNCs) have been widely used for the preparation of Pickering emulsion . Both are believed playing good role of particle emulsifiers. However, these two kinds of nanocrystals have completely different surface properties: electronegative CNC is more hydrophilic and has higher surface charge level as compared to electropositive ChNC. To reveal their difference as emulsifiers in Pickering emulsions is therefore of interest. In this work, ChNCs and CNCs with the same structural parameters (aspect ratio = 28) were used to prepare olive oil- in -water emulsions for a comparative study. The two kinds of nanocrystals show the same mechanical state in emulsions, behaving like rigid rods, instead flexible fibers because they have 10 4 level of effective stiffness. Therefore, their roles of emulsifying oil/water system are dominated by their surface properties: ChNCs reveal higher emulsifying capacity relative to CNCs due to better ChNC-oil affinity, and can even emulsify the oil/water (7/3 w/w) system with high oil fractions. However, ChNC-stabilized emulsions are not that stable to centrifugation as compared to CNC-stabilized emulsions at low oil fractions due to the formation of the cluster structure resulted from less coating of droplets. Thus, the former reveals higher strain sensitivity and stronger thixotropy than the latter in shear flow. The correlation between viscoelasticity and morphology/phase behavior of the two kinds of Pickering systems was assessed, then. This work provides valuable information on formulating preparation of Pickering emulsions by using different types of rod-like polysaccharide nanocrystals.

Valuable aramid/cellulose nanofibers derived from recycled resources for reinforcing carbon fiber/phenolic composites

Shanshan Ma,Hejun Li,Chang Li,Bo Li,Jie Fei,Yangbing Wen

The scale-up preparation of aramid nanofiber (ANF) and cellulose nanofiber (CNF), still faces serious challenges such as extreme production cost and lengthy preparation cycle. Herein, a feasible top-down strategy was proposed to achieve the efficient reclamation of waste resources, further realizing the large-scale production of high value-added nanofibers. The ANF/CNF as nanoscale building blocks and their reinforcement effects on the mechanical performances of carbon fiber/phenolic composites were investigated. Related strength and modulus of ANF/CNF-enhanced composites in the tensile, bending, shear and nano indentation tests, increased by 118.1% (tensile strength), 141.2% (tensile modulus), 142.2% (flexural strength), 354.4% (flexural modulus), 38.8% (shear strength) and 94.4% (elastic modulus), respectively. Our work offers a valuable reference in the fabrication of low-cost ANF/CNF derived from waste resources, which would facilitate the wide application of nanofibers in fabricating high-performance advanced functional materials.

Ultra-stable pickering emulsions stabilized by zein-cellulose conjugate particles with tunable interfacial affinity

Yijie Wang,Xiufeng Li,Ting Li,Yang Wang,Jie Jiang,Xuhui Zhang,Jing Huang,Bihua Xia,Ho Cheung Shum,Zhenzhong Yang,Weifu Dong

Designing solid particles with desirable interfacial affinity from plant-based ingredients is a key area in sustainable food production. Here, a chemical approach is introduced to fabricate conjugate particles by combining a water-insoluble plant protein (zein) and a hydrophilic polysaccharide (cellulose) through Schiff-base reaction. Zein assembles and precipitates into anisotropic particles after forming conjugates with cellulose . The wettability of conjugate particles at the interface can be precisely engineered by adjusting the ratio of the hydrophobic and hydrophilic components. The three-phase contact angle of a water droplet sitting on the substrate made of particles can be adjusted in a range from around 130°–40° when they are submerged in corn oil. The interfacial absorption kinetics of conjugate particles shows 2 to 4 times improvement than the particles made from sole material sources. The optimal polymer ratio is found to be 1:1.5 and 1:2 (zein:cellulose) for the corn oil-water system. In association with the enhanced interfacial affinity, emulsions stabilized by conjugate particles exhibit superior stability against droplet coalescence and bulk phase separation when going through the isoelectric point of the protein (around pH 6), high ionic strength, long-term storage, and thermal treatment. It has been found that 0.5 wt% conjugate particles are enough to stabilize emulsions containing more than 60 vt% oil.

Perhydropolysilazane-derived-SiOx coated cellulose: a transparent biodegradable material with high gas barrier property

Yue Shuangshuang,Wang Shuanjin,Han Dongmei,Huang Sheng,Xiao Min,Meng Yuezhong

A transparent perhydropolysilazane-derived-SiO x coated cellulose film with high gas barrier properties was fabricated via a facile solution dip-coating followed by UV curing method. The conversion of perhydropolysilazane to SiO x was proved by ATR-FTIR, XPS and TOF–SIMS characterizations. AFM and SEM images revealed the smoothness of the coating and good adhesion between the cellulose substrate and the coating. The thickness of the SiO x coating (50–450 nm) can be tuned by changing the concentration of the perhydropolysilazane precursor solution. The cellulose film (35 µm in thickness) with 450 nm thick SiO x coating exhibits low oxygen transmission rate (OTR) value of 0.82 cm 3 /m 2 ·day and water vapor transmission rate (WVTR) value of 1.28 g/m 2 ·day. The excellent oxygen and water vapor barrier properties, ultrahigh transparency and complete biodegradability of the SiO x coated cellulose film endow it competitive potential for packaging applications. Graphical abstract A transparent perhydropolysilazane-derived-SiO x layer is tightly coated on a cellulose film via a facile solution dip-coating followed by UV curing method. The sandwich structured cellulose-SiO x films show excellent oxygen and water vapor barrier properties as well as ultrahigh transparency and complete biodegradability, which has a great potential for food, medicine and other packaging applications.

Flexible Recyclable Cellulose Paper Templated Cu-Doped Polydopamine Membranes with Dual Enzyme-Like Activity

Hong Li,Zhuzhu Xiong,Yi Jia,Fan Gao,Chenlei Wang,Qi Li,Junbai Li

The development of high-efficiency enzyme mimics is of great significance in the field of biocatalysis. However, it remains challenging to design novel enzyme mimics with multiple enzyme-like activities, excellent stability, and good reusability. Herein, a facile molecular assembly strategy to construct dialdehyde cellulose (DAC) templated Cu-doped polydopamine (DAC@PDA/Cu) membrane with dual enzyme-like activities is presented. The Schiff base bonds formed between polydopamine (PDA) and DAC can not only accelerate the adhesion of PDA thin layer but also contribute to Cu-loading and high stability of DAC@PDA/Cu membrane. Importantly, the assembled DAC@PDA/Cu membrane exhibits a remarkable catalytic activity that is superior to the natural laccase along with high stability and excellent reusability. Moreover, the DAC@PDA/Cu membrane also demonstrates peroxidase-like activity, and it is successfully applied in the sensitive detection of ascorbic acid (AA). This work will provide a new paradigm methodology for rational design and practical applications of enzyme mimics based on bioinspired molecular assemblies.

Heat Soaking Pretreatment for Greener Production of Phosphorylated Cellulose Nanofibrils with Higher Charge Density

Shaohuang Chen,Ning Ren,Mei Cui,Renliang Huang,Wei Qi,Zhimin He,Rongxin Su

Phosphorylated cellulose nanofibrils (PCNFs) made from woody biomass have aroused immense interest because of their promising applications in various fields, including flame retardancy, adsorption, and separation. However, traditional production methods show high chemical and energy consumption, while the obtained PCNFs have lower charge density. In this study, PCNFs with higher charge density (2.09–3.79 mmol·g–1) were produced by tuning heat soaking pretreatment of cellulose fibers in phosphate salt and urea solutions, followed by curing and mechanical fibrillation. An optimized pretreatment can be achieved by heat-assisted soaking at 80 °C for 25 min, which was effective to produce PCNFs with greater performance (e.g., higher charge and crystallinity) compared to those of traditional methods. Furthermore, the optimized route is more sustainable with a substantial decrease in resource consumption including chemicals (33.6%), water (55.8%), and energy (65.3%), and the production costs would be saved by 62.0% in comparison with the traditional route. Such a sustainable and economic process has great potential in the industrial production of PCNFs.

Porous fibrous bacterial cellulose/La(OH)3 membrane for superior phosphate removal from water

Liping Tan,Weihua Zhang,Xiaoguang Zhu,Yue Ru,Wenbo Yi,Bo Pang,Tongjun Liu

Lanthanum (La)-based nanoparticles (NPs) are promising candidates for phosphate removal owing to their inherently high affinity towards phosphate. However, significant challenges remain to be addressed before their practical deployment, especially the problems associated with their aggregation. Herein, we fabricated a high-efficient sorbent for phosphate removal through in-situ synthesizing La(OH) 3 NPs on a natural support, bacterial cellulose (BC), which is pre-modified with polyethyleneimine. The resultant La(OH) 3 NPs-immobilized BC with different La contents (BPLa-X) exhibited a highly fibrous porous structure, in which BPLa-3 was selected for further phosphate adsorption studies. BPLa-3 demonstrated a high adsorption capacity of 125.5 mg P g −1 , and high adsorption selectivity due to the large surface area and abundant exposed active adsorption sites for phosphate. Additionally, BPLa-3 also displayed high reusability and still possessed high adsorption capacity after four consecutive cycles of adsorption-desorption. Therefore, the present adsorbent is believed to be a promising candidate for practical phosphate removal.

Cellulose nanofiber/MXene/FeCo composites with gradient structure for highly absorbed electromagnetic interference shielding

Meng Ma,Wenting Tao,Xianjun Liao,Si Chen,Yanqin Shi,Huiwen He,Xu Wang

Conductive polymer composites (CPCs) had attracted tremendous attention in the field of electromagnetic interference (EMI) shielding. However, these materials encountered an intrinsic contradiction between high EMI shielding effectiveness (EMI SE) and low electromagnetic waves reflection. Herein, an excellent EMI SE and low electromagnetic waves reflection composite film with a controllable magnetic-conductive dual gradient structure was constructed using cellulose nanofiber (CNF), MXene, and FeCo by layer-by-layer vacuum filtration method. Benefiting from the synergy of the transition layers and reflection layer with gradient structure, the composite film exhibited favorable impedance matching, abundant loss mechanism, and efficient EMI shielding ability, resulting in absorption dominated shielding characteristic. In addition, the gradient structure facilitated the “absorb-reflect-reabsorb” process when electromagnetic waves were transmitted into the composite film. The obtained CNF/MXene/FeCo-G composite film possessed a remarkable EMI SE of 58.0 dB and the reflection coefficient (R) as low as 0.61. It was proven that the electromagnetic waves absorbing ability can be enhanced by thickening the transition layers, and the EMI SE was improved with the thickening of the reflection layer. Therefore, this work provided a facile strategy to prepare high EMI SE materials with low reflection, which had a good application prospect as the new-generated smart electronic devices.

Development of alginate-chitosan composite scaffold incorporation of bacterial cellulose for bone tissue engineering

Qingmei Zhu,Xiuqiong Chen,Zhaowen Liu,Zhengyue Li,Dongze Li,Huiqiong Yan,Qiang Lin

Bacterial laccase immobilized on a magnetic dialdehyde cellulose without cross-linking agents for decolorization

Weichuan Qiao,Ziyan Zhang,Yi Qian,Lijie Xu,He Guo

In the process of using cross-linking method to immobilize enzymes, cross-linker have a certain negative effect on immobilization efficiency. In this study, a magnetic dialdehyde cellulose (MDAC) was prepared by oxidizing hydroxyl groups in cellulose to aldehyde groups. The modified cellulose could be used for the immobilization of bacterial laccase without cross-linker. The morphology and structure of the MDAC–laccase complex (MDAC-L) confirmed that the laccase was immobilized on MDAC via -CHO in MDAC and -NH 2 in laccase. Under conditions of pH 4 and 45 °C, the maximum loading capacity of MDAC-L reached 210.74 mg/g, and relatively high enzyme activities maintained,. Compared with free laccase and immobilized laccase with glutaraldehyde , MDAC-L exhibited a wide pH range, temperature stability, reusability, and is suitable for long-term storage at low temperature. MDAC-L also improved the tolerance of free laccase to the presence of organic solvents , inhibitors and metal ions . Furthermore, the maximum saturation magnetization of MDAC-L was 34.07 emu/g, allowing for rapid magnetic separation. The relative activity of the immobilized laccase remained about 70% after 10 cycles of reuse. In addition, MDAC-L showed good decolorization performance when applied to crystal violet . Under the conditions of 45 °C and pH 6 for 21 h, the decolorization rate can reach about 90%. This study developed a novel cross-linking method for enzyme immobilization.

Cellulose nanospheres coated polylactic acid nonwoven membranes for recyclable use in oil/water separation

Lu Jun,Wen Jiexiu,Yu Qihao,Cui Chaofan,Su Juanjuan,Han Jian

Oily wastewater has always been an environmental issue that we are concerned about and committed to managing. Although the superwetting membranes have been extensively studied and widely used in oil/water separation, the abundant discarded membranes are still headaches due to their non-degradable nature. In this work, all-around green material, as well as superhydrophilic polylactic acid (PLA) nonwoven membrane, is designed by coating cellulose nanospheres (CNCs) with the aid of polydopamine (PDA). Plenty of hydroxyl groups and hierarchical rough structure synergistically contribute to the superhydrophilicity and excellent oil/water separation performance of the resultant CNCs/PDA/PLA nonwoven membrane. Interestingly, the efficiency of oil/water separation can be maintained above 98% after 100 times of repeated use. With the outstanding durability and easy controllability, the CNCs/PDA/PLA nonwoven membrane may provide effective solutions to manage the oily wastewater and secondary pollution of the used membrane itself simultaneously. Graphic abstract