CN104451961A - Method for preparing superconducting micron fiber - Google Patents

Method for preparing superconducting micron fiber Download PDF

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CN104451961A
CN104451961A CN201410548429.4A CN201410548429A CN104451961A CN 104451961 A CN104451961 A CN 104451961A CN 201410548429 A CN201410548429 A CN 201410548429A CN 104451961 A CN104451961 A CN 104451961A
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nfc
microfibers
micrometer fibers
fiber
fibers
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戴红旗
李媛媛
胡良兵
祝红丽
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Nanjing Forestry University
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Nanjing Forestry University
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Abstract

本发明公开了一种制备超导电微米纤维的方法,包括:1)TEMPO氧化纤维素一次通过微射流机以后制备得到NFC;2)采用Hummer’s法对石墨进行氧化而得到GO;3)高强度微米纤维的制备:把纺丝液通过针管挤出到酒精凝固浴里析出,形成凝胶纤维,然后将凝胶纤维拉出凝固浴在空气中干燥;在干燥过程中,在微米纤维两端施加一定的作用力,以提高微米纤维的取向度;干燥后把微米纤维置于10wt% CaCl2的水溶液中浸渍1小时后重新干燥;4)对高强度微米纤维进行炭化得到导电GO+NFC微米纤维。本发明得到的c(GO+NFC)微米纤维的平均导电率为649±60 S/cm,是现今报道的最导电率,高于炭化NFC微米纤维和炭化GO微米纤维导电率。同时,制备使用低密度的NFC与GO,原料来源广泛。

The invention discloses a method for preparing superconducting microfibers, which includes: 1) TEMPO oxidized cellulose passes through a micro-fluidizer once to prepare NFC; 2) Hummer's method is used to oxidize graphite to obtain GO; 3) high-strength micron fibers Fiber preparation: Extrude the spinning solution through a needle into an alcohol coagulation bath to form a gel fiber, then pull the gel fiber out of the coagulation bath to dry in the air; during the drying process, apply a certain to improve the orientation of the microfibers; after drying, immerse the microfibers in a 10wt% CaCl 2 aqueous solution for 1 hour and re-dry; 4) Carbonize the high-strength microfibers to obtain conductive GO+NFC microfibers. The average conductivity of the c(GO+NFC) microfibers obtained in the present invention is 649±60 S/cm, which is the highest conductivity reported so far, and is higher than that of carbonized NFC microfibers and carbonized GO microfibers. At the same time, low-density NFC and GO are used in the preparation, and the raw materials come from a wide range of sources.

Description

一种制备超导电微米纤维的方法A method for preparing superconducting microfibers

技术领域 technical field

本发明涉及超强微米纤维技术领域,特别涉及一种制备超导电微米纤维(c(GO+NFC))的方法。 The invention relates to the technical field of ultra-strong micron fibers, in particular to a method for preparing superconductive micron fibers (c(GO+NFC)).

背景技术 Background technique

纳米纤维素具有优异的性能,现已被用于制备超强材料、导电材料等用于电子设备、生物医药、食品、包装等领域。纤维是具有广泛用途的材料,其应用领域涉及到纺织、建筑甚至飞机、汽车等的制备上。目前高性能低成本微米纤维的制备引起人们的广泛关注。由纳米纤维素制备的功能微米纤维已渐渐成为热门。 Nanocellulose has excellent properties, and has been used to prepare super-strong materials, conductive materials, etc. for electronic equipment, biomedicine, food, packaging and other fields. Fiber is a material with a wide range of uses, and its application fields involve the preparation of textiles, construction, and even aircraft and automobiles. At present, the preparation of high-performance and low-cost micron fibers has attracted widespread attention. Functional microfibers prepared from nanocellulose have gradually become popular.

力学性能优异的合成纤维(如碳纤维)在飞机、风力发电的涡轮叶片制备中扮演重要的角色。但是这些合成纤维价格昂贵,性能有限。因而对低成本高性能的纤维制备研究现已成为热点。纳米纤维素具有力学性能优异、来源广泛、绿色等特点,已被用来制备高强度材料或者材料的增强剂。二维纳米氧化石墨烯(GO)也是有优异机械性能、高比表面积,可用于制备超强材料的结构单元材料。GO片的表面以及边缘有因为化学反应而引入的大量羟基、羧基以及环氧基,这些基团使得GO在水中可以稳定分散,在材料中形成强的作用力。对于将低成本的二维GO用于制备一维微米纤维,现在已成为研究热点。为了提高GO微米纤维的强度,常用的方法有化学交联、聚合物包裹涂覆、离子键结合以及提高GO单片的质量等。目前报道的机械强度最好的GO微米纤维,抗张强度可达442MPa,弹性模量有47GPa。然而要想在实际应用中取代碳纤维,GO纤维的强度还需要进一步提高。 Synthetic fibers with excellent mechanical properties (such as carbon fibers) play an important role in the preparation of aircraft and wind power turbine blades. But these synthetic fibers are expensive and have limited performance. Therefore, the research on low-cost and high-performance fiber preparation has become a hot spot. Nanocellulose has the characteristics of excellent mechanical properties, wide range of sources, green, etc., and has been used to prepare high-strength materials or reinforcing agents for materials. Two-dimensional nano-graphene oxide (GO) is also a structural unit material with excellent mechanical properties and high specific surface area, which can be used to prepare super-strong materials. The surface and edge of the GO sheet have a large number of hydroxyl, carboxyl and epoxy groups introduced due to chemical reactions. These groups make GO stable in water and form a strong force in the material. The use of low-cost two-dimensional GO for the preparation of one-dimensional microfibers has become a research hotspot. In order to improve the strength of GO microfibers, common methods include chemical crosslinking, polymer coating, ionic bonding, and improving the quality of GO monoliths. The GO micron fiber with the best mechanical strength reported so far has a tensile strength of 442MPa and an elastic modulus of 47GPa. However, in order to replace carbon fibers in practical applications, the strength of GO fibers needs to be further improved.

纤维素是自然界中储量最多的生物大分子聚合物。它是用于制备碳材料的重要原料。由纤维素制备的碳材料在能量存储、碳纤维制备、水处理、催化等领域发挥了重要作用。由纤维素制备碳材料的重要手段是对纤维素进行炭化,主要包括在特定气氛下加热炭化和水热炭化两种。纤维素在炭化过程中,发生糖苷键断裂、纤维的降解、含氧和氢的气体释放,最终形成碳材料。但是通常得到的纤维素碳材料导电性比较低。如碳纤维的导电性在炭化温度为1000℃时为30S/cm左右。为得到高导电性的碳材料,通常要提高炭化温度。因为提高炭化温度可以提高碳材料内部石墨化程度,进而改善导电性。将炭化温度提高到2000℃时,碳纤维的导电性可以提高到100S/cm。但是,高温处理对设备的要求极高,使得导电纤维制备成本增加。 Cellulose is the most abundant biomacromolecular polymer in nature. It is an important raw material for the preparation of carbon materials. Carbon materials prepared from cellulose have played an important role in energy storage, carbon fiber preparation, water treatment, catalysis and other fields. An important means of preparing carbon materials from cellulose is to carbonize cellulose, which mainly includes heating carbonization and hydrothermal carbonization under a specific atmosphere. During the carbonization process of cellulose, the glucosidic bonds are broken, the fibers are degraded, the gases containing oxygen and hydrogen are released, and finally carbon materials are formed. However, the generally obtained cellulose carbon materials have relatively low conductivity. For example, the conductivity of carbon fiber is about 30S/cm when the carbonization temperature is 1000°C. In order to obtain highly conductive carbon materials, it is usually necessary to increase the carbonization temperature. Because increasing the carbonization temperature can increase the degree of graphitization inside the carbon material, thereby improving the electrical conductivity. When the carbonization temperature is increased to 2000°C, the conductivity of carbon fibers can be increased to 100S/cm. However, the high temperature treatment has extremely high requirements on equipment, which increases the cost of preparing conductive fibers.

发明内容 Contents of the invention

发明目的:针对现有技术中存在的不足,本发明的目的在于提供一种制备超导电微米纤维的方法,将GO与纳米纤维素(NFC)相结合制备出高强度微米纤维,提高了混合纤维的强度,然后再炭化处理,获得超导电微米纤维。 Purpose of the invention: In view of the deficiencies in the prior art, the purpose of the present invention is to provide a method for preparing superconducting micron fibers, combining GO and nanocellulose (NFC) to prepare high-strength micron fibers, which improves the performance of mixed fiber strength, and then carbonized to obtain superconducting micron fibers.

技术方案:为了实现上述发明目的,本发明采用的技术方案如下: Technical solution: In order to realize the above-mentioned purpose of the invention, the technical solution adopted in the present invention is as follows:

一种制备超导电微米纤维的方法,包括以下步骤: A method for preparing superconducting microfibers, comprising the steps of:

1)TEMPO氧化纤维素一次通过微射流机以后制备得到NFC; 1) NFC is prepared by TEMPO oxidized cellulose passing through a microfluidizer once;

2)采用Hummer’s法对石墨进行氧化而得到GO; 2) Oxidation of graphite by Hummer's method to obtain GO;

3)高强度微米纤维的制备:把纺丝液通过针管挤出到酒精凝固浴里析出,形成凝胶纤维,然后将凝胶纤维拉出凝固浴在空气中干燥;在干燥过程中,在微米纤维两端施加0.5N的作用力,以提高微米纤维的取向度;干燥后把微米纤维置于10wt% CaCl2的水溶液中浸渍1小时后重新干燥; 3) Preparation of high-strength micron fibers: Extrude the spinning solution through a needle tube into an alcohol coagulation bath to form a gel fiber, and then pull the gel fiber out of the coagulation bath to dry in the air; during the drying process, the micron A force of 0.5N is applied to both ends of the fiber to increase the degree of orientation of the micron fiber; after drying, the micron fiber is immersed in an aqueous solution of 10wt% CaCl for 1 hour and then dried again;

4)对高强度微米纤维进行炭化得到导电GO+NFC微米纤维。 4) Carbonize high-strength micron fibers to obtain conductive GO+NFC micron fibers.

步骤1)中:5g未干燥过的绝干针叶木浆与78mg TEMPO,514mg NaBr充分混合均匀;反应通过30mL 12%NaClO的加入引发,并在室温搅拌下发生反应;体系的pH值通过NaOH控制稳定在10.5;直至体系内剩余NaClO反应完全结束;反应后的浆料通过过滤洗涤干净,至pH呈中性;将得到的纤维配成1%的浓度通过微射流机在5~25KPa压力下处理;得到透明纳米纤维素分散液;分散液贮存与4℃冰箱。 Step 1): 5g undried absolute-dried softwood pulp, 78mg TEMPO, 514mg NaBr are fully mixed; the reaction is initiated by the addition of 30mL 12%NaClO, and the reaction occurs under stirring at room temperature; the pH value of the system is controlled by NaOH Stable at 10.5; until the reaction of the remaining NaClO in the system is completely completed; the reacted slurry is cleaned by filtration until the pH is neutral; the obtained fiber is made into a concentration of 1% and processed under a pressure of 5-25KPa by a micro-fluidizer ; Obtain a transparent nanocellulose dispersion; store the dispersion in a refrigerator at 4°C.

步骤2)中:将3.0g石墨鳞片、1.5g NaNO3在0℃下混合均匀;然后把69mL 98%H2SO4加进去混合搅拌均匀,最后慢慢加入9.0g KMnO4;添加KMnO4时溶液温度控制在低于20℃,加完KMnO4后将反应体系温度升高到35℃搅拌30min;然后将138mL去离子水慢慢滴加进入反应体系,并且控制反应温度在98℃保持15min;紧接着将反应体系降温到室温,同时另外添加420mL去离子水与3mL 30%C的H2O2;等反应混合物冷却到室温时,将物料在布氏漏斗中用去离子水洗涤至中性;得到的GO用超声分散在水中待用。 Step 2): Mix 3.0g graphite flakes and 1.5g NaNO 3 at 0°C; then add 69mL 98%H 2 SO 4 and mix well, and finally add 9.0g KMnO 4 slowly; when adding KMnO 4 The temperature of the solution is controlled below 20°C. After adding KMnO 4 , raise the temperature of the reaction system to 35°C and stir for 30 minutes; then slowly add 138mL of deionized water into the reaction system dropwise, and control the reaction temperature at 98°C for 15 minutes; Immediately after cooling the reaction system to room temperature, add 420 mL of deionized water and 3 mL of 30% C H 2 O 2 at the same time; when the reaction mixture is cooled to room temperature, wash the material in a Buchner funnel with deionized water until neutral ; The obtained GO was dispersed in water by ultrasound for use.

步骤3)中,所述的纺丝液为GO和NFC质量比 1:1配制好的浓度为1.1wt%的液晶溶液。 In step 3), the spinning solution is a liquid crystal solution with a concentration of 1.1wt% prepared with a mass ratio of GO and NFC of 1:1.

步骤4)中,高强度微米纤维的炭化在95%氩气与5%氢气混合气氛中进行;升温程序如下:先从室温到以30℃/h的升温速率升到400℃,之后以200℃/h的升温速率升到1000℃,最后在1000℃下保温2h。 In step 4), the carbonization of high-strength micron fibers is carried out in a mixed atmosphere of 95% argon and 5% hydrogen; the heating program is as follows: first from room temperature to 400°C at a heating rate of 30°C/h, and then at 200°C The heating rate is increased to 1000°C per hour, and finally kept at 1000°C for 2h.

所述的制备超导电微米纤维的方法所获得的超导电微米纤维。 Superconducting microfibers obtained by the method for preparing superconducting microfibers.

所述的超导电微米纤维作为导电材料的应用。 The application of the superconducting micron fiber as a conducting material.

有益效果:与现有技术相比,本发明具有如下优点及突出性效果:得到的c(GO+NFC)微米纤维的平均导电率为649±60 S/cm,是现今报道的由石墨、GO以及GO复合物制备的导电纤维的最导电率,高于炭化NFC微米纤维(平均导电率为33S/cm)和炭化GO微米纤维导电率(平均导电率为137S/cm)。同时,制备使用低密度的NFC与GO,原料来源广泛,纤维制备方法简单具有大规模生产的潜在价值。 Beneficial effects: Compared with the prior art, the present invention has the following advantages and outstanding effects: The average conductivity of the obtained c(GO+NFC) micron fibers is 649±60 S/cm, which is the highest reported by graphite, GO And the highest conductivity of conductive fibers prepared by GO composites is higher than that of carbonized NFC microfibers (average conductivity 33S/cm) and carbonized GO microfibers (average conductivity 137S/cm). At the same time, low-density NFC and GO are used in the preparation, the source of raw materials is extensive, and the fiber preparation method is simple, which has the potential value of large-scale production.

附图说明 Description of drawings

图1是TEMPO法氧化纤维素的表征结果图; Fig. 1 is the characterization result figure of TEMPO method oxidized cellulose;

图2是TEMPO氧化纤维素一次通过微射流机以后便可得到NFC的表征结果图; Figure 2 is a diagram of the characterization results of NFC obtained after TEMPO oxidized cellulose passes through the microfluidizer once;

图3是GO+NFC微米纤维的制备流程图; Fig. 3 is the preparation flowchart of GO+NFC micron fiber;

图4是高强度微米纤维的结构示意图; Fig. 4 is the structural representation of high-strength micron fiber;

图5是制备原料以及混合液的表征图; Fig. 5 is the characterization figure of preparation raw material and mixed solution;

图6是高强度微米纤维的表征图; Fig. 6 is a characterization diagram of high-strength microfibers;

图7是对照样的表征图; Fig. 7 is the characterization diagram of control sample;

图8是GO微米纤维、NFC微米纤维以及GO+NFC微米纤维的应力应变曲线图; Fig. 8 is a stress-strain curve diagram of GO micron fiber, NFC micron fiber and GO+NFC micron fiber;

图9是纤维炭化前后的示意图; Fig. 9 is a schematic diagram before and after fiber carbonization;

图10是炭化后的SEM图; Fig. 10 is the SEM figure after carbonization;

图11是c(GO+NFC)纤维的I-V曲线。 Figure 11 is the I-V curve of c(GO+NFC) fibers.

具体实施方式 Detailed ways

下面结合具体实施例对本发明做进一步的说明,但本发明不受以下实施例的限制。  The present invention will be further described below in conjunction with specific examples, but the present invention is not limited by the following examples. the

以下实施例中使用到的主要试剂与仪器如下: The main reagents and instruments used in the following examples are as follows:

漂白针叶木浆板为巴西红鱼牌,浆先经过瓦力打浆机打到加拿大游离度为150mL。紫外光谱仪UV-Vis Spectrometer Lambda 35(PerkInElmer,USA);透射电镜(TEM,FEI QUANTA 200,美国);动态力学分析仪分析(DMA,Q800);日立(HITACHI)S-510扫描电镜;超声仪(FS 110D,Fisher Scientific)。 The bleached coniferous wood pulp board is Brazilian Red Fish brand, and the pulp is first beaten by a Wall-E beater to a Canadian freeness of 150mL. Ultraviolet spectrometer UV-Vis Spectrometer Lambda 35 (PerkInElmer, USA); transmission electron microscope (TEM, FEI QUANTA 200, USA); dynamic mechanical analyzer analysis (DMA, Q800); Hitachi (HITACHI) S-510 scanning electron microscope; ultrasonic instrument ( FS 110D, Fisher Scientific).

实施例1 NFC制备与表征 Example 1 NFC preparation and characterization

5g未干燥过的绝干针叶木浆与78mg TEMPO,514mg NaBr充分混合均匀。反应通过30mL 12%NaClO的加入引发,并在室温搅拌下发生反应。体系的pH值通过NaOH控制稳定在10.5。直至体系内剩余NaClO反应完全结束。反应后的浆料通过过滤洗涤干净,至pH呈中性。将得到的纤维配成1%的浓度通过微射流机5~25KPa压力下处理。得到透明纳米纤维素(NFC)分散液。分散液贮存与4℃冰箱内待用。 5g undried absolute dry softwood pulp, 78mg TEMPO, 514mg NaBr are fully mixed evenly. The reaction was initiated by the addition of 30 mL of 12% NaClO and reacted with stirring at room temperature. The pH value of the system was stabilized at 10.5 by NaOH control. Until the reaction of the remaining NaClO in the system is completely completed. The reacted slurry was washed by filtration until the pH was neutral. The obtained fibers are formulated into a concentration of 1% and processed under a pressure of 5-25KPa by a micro-fluidizer. A transparent nanocellulose (NFC) dispersion was obtained. Store the dispersion in a refrigerator at 4°C until use.

扫描电镜(SEM)观察:将待测样品进行真空干燥后,粘台、真空喷金,操作条件电压为20kV。 Scanning Electron Microscope (SEM) Observation: After the sample to be tested is vacuum-dried, glued to the table and vacuum-sprayed with gold, the operating condition voltage is 20kV.

纳米纤维素的长宽度采用透射电镜与纤维形貌通过原子力显微镜(AFM)表征。TEM制样时滴10μL纳米纤维素溶液在炭网上,多余的液体用滤纸吸走,操作电压为100kV。AFM制样时,滴10μL纳米纤维素溶液在1cm×1cm的硅片上,通过旋涂仪将纳米纤维素在硅片上涂匀。干燥后在轻敲模式下进行观察表征。 The length and width of nanocellulose were characterized by transmission electron microscopy and fiber morphology by atomic force microscopy (AFM). When preparing samples for TEM, drop 10 μL of nanocellulose solution on the carbon grid, absorb the excess liquid with filter paper, and operate at a voltage of 100 kV. When preparing AFM samples, drop 10 μL of nanocellulose solution on a 1 cm × 1 cm silicon wafer, and spread the nanocellulose evenly on the silicon wafer by a spin coater. Visual characterization was performed in tapping mode after drying.

溶液Zeta电位通过Zeta电位测试仪得到。测试时NFC溶液质量分数为0.7 mg/mL,pH为7.8。 The Zeta potential of the solution was obtained by a Zeta potential tester. During the test, the mass fraction of NFC solution was 0.7 mg/mL, and the pH was 7.8.

表征结果如图1所示,其中a-c是TEMPO 氧化纤维的SEM图,d是TEMPO氧化纤维制备的透明纸,e是将导电墨水写到TEMPO氧化纤维制备的纸上,f是电表测试显示写上的导电线具有良好的导电性,g是在TEMPO氧化纤维制备的纸上通过圆珠笔画得二极管。TEMPO氧化处理纤维以后,纤维表面C6位羟基被氧化为羧基,增加了纤维上的带电基团含量。同时由于纤维的氧化反应与机械搅拌的作用力,纤维间的结合强度降低,纤维表面发生细胞壁的破损,甚至出现纵向开裂(图1中的a-b)。与此同时,纤维的长度降低、宽度降低,溶液中细小纤维含量增加。高倍扫面电镜下观察纤维表面(图1中的c)可知,表面含有大量的微细纤维,并且呈网状排列。这符合木材初生壁内微细纤维的结构。TEMPO氧化后的纤维虽然绝大部分仍为微米纤维,但是溶液具有一定的粘度与透明度。直接过滤TEMPO氧化后的纤维可以得到透明且有一定雾度的纸(图1中的d)。同时纸张保持了良好的书写性能,与表面光滑度。表面光滑度可能主要有制备过程中产生的纳米纤维沉积在纸张表面造成。图1中的e-g为在纸张上书写导电材料,制备可书写的纸基电子设备。 The characterization results are shown in Figure 1, where a-c is the SEM image of TEMPO oxidized fiber, d is the transparent paper prepared by TEMPO oxidized fiber, e is the conductive ink written on the paper prepared by TEMPO oxidized fiber, and f is the electric meter test display to write The conductive wire has good conductivity, and g is a diode drawn by a ballpoint pen on paper prepared from TEMPO oxidized fiber. After the fiber is oxidized by TEMPO, the C6 hydroxyl group on the fiber surface is oxidized to a carboxyl group, which increases the charged group content on the fiber. At the same time, due to the oxidation reaction of the fibers and the force of mechanical stirring, the bonding strength between the fibers is reduced, the cell wall is damaged on the fiber surface, and even longitudinal cracks appear (a-b in Figure 1). At the same time, the length and width of the fibers decreased, and the content of fine fibers in the solution increased. Observing the surface of the fiber under a high-power scanning electron microscope (c in Figure 1) shows that the surface contains a large number of fine fibers, which are arranged in a network. This is consistent with the structure of fine fibers in the primary wall of wood. Although most of the fibers oxidized by TEMPO are still micron fibers, the solution has a certain viscosity and transparency. Direct filtration of TEMPO-oxidized fibers can produce transparent paper with a certain degree of haze (d in Figure 1). At the same time, the paper maintains good writing performance and surface smoothness. The surface smoothness may be mainly caused by the deposition of nanofibers generated during the preparation process on the paper surface. e-g in Fig. 1 are writing conductive materials on paper to prepare writable paper-based electronic devices.

TEMPO氧化纤维素一次通过微射流机以后便可得到NFC,结果如图2所示,其中,低倍a与高倍b下得NFC 的TEM图,c为NFC的AFM图,d为NFC溶液,e为绿色激光照射NFC溶液,f为NFC溶液浓度为1%时的偏光显微镜图片,g为NFC凝胶。通过微射流机的压力越大,得到的NFC尺寸越小。图2中的a为通过25KPa压力的微射流机处理得到的NFC。其直径小于10nm,长度在几百纳米。高倍率TEM图(图2中的b)显示NFC具有漂亮的结晶结构。AFM也被用来表征NFC形貌(图2中的c),AFM图中显示的NFC直径略大于TEM结果,这与表征手段有关。NFC的水溶液的特点在于其光学透明性(图2中的d),以及纳米溶液的丁达尔现象。由于NFC表明含有TEMPO氧化引入的带电基团,NFC可以稳定分散在水中。对NFC溶液进行Zeta电位测试知:溶液的Zeta电位为-64.9mV,证实了溶液的良好稳定性。NFC具有自组装的特性,当NFC溶液浓度为1%时,溶液开始体现出液晶形态,如图2中的e所示。进一步提高NFC溶液的浓度,NFC凝胶变会形成,如图2中的f。制备得到的NFC直径大约10nm,长度在100-400nm范围(图5中的b),在NFC浓度为1.0wt%时开始形成液晶相。 NFC can be obtained after TEMPO oxidized cellulose passes through the microfluidizer once, and the results are shown in Figure 2, where the TEM images of NFC are obtained at low magnification a and high magnification b, c is the AFM image of NFC, d is the NFC solution, e The NFC solution is irradiated by the green laser, f is the polarizing microscope picture when the concentration of the NFC solution is 1%, and g is the NFC gel. The higher the pressure through the microfluidizer, the smaller the resulting NFC size. A in Figure 2 is the NFC obtained by the micro-fluidizer with a pressure of 25KPa. Its diameter is less than 10nm and its length is several hundred nanometers. The high-magnification TEM image (b in Figure 2) shows that the NFC has a beautiful crystalline structure. AFM is also used to characterize the NFC morphology (c in Figure 2), and the diameter of NFC shown in the AFM image is slightly larger than the TEM result, which is related to the characterization means. Aqueous solutions of NFC are characterized by their optical transparency (d in Fig. 2), as well as the Tyndall phenomenon of nanosolutions. Since NFC is shown to contain charged groups introduced by TEMPO oxidation, NFC can be stably dispersed in water. The Zeta potential test of the NFC solution shows that the Zeta potential of the solution is -64.9mV, which confirms the good stability of the solution. NFC has the characteristics of self-assembly. When the concentration of NFC solution is 1%, the solution begins to show the liquid crystal form, as shown in e in Figure 2. Further increase the concentration of NFC solution, NFC gel will be formed, as shown in Figure 2 f. The prepared NFC has a diameter of about 10nm and a length in the range of 100-400nm (b in Figure 5), and the liquid crystal phase begins to form when the NFC concentration is 1.0wt%.

实施例2 氧化石墨烯(GO)的制备 Example 2 Preparation of Graphene Oxide (GO)

GO采用Hummer’s法对石墨进行氧化而得到。具体方法如下:将石墨鳞片(3.0g,1wt. 相对质量含量)、NaNO3(1.5g,0.5 wt. 相对质量含量)在0℃下混合均匀。然后把H2SO4(98%,69mL)加进去混合搅拌均匀,最后慢慢加入KMnO4(9.0g,3wt. 相对质量含量)。添加KMnO4时溶液温度控制在低于20℃,加完KMnO4后将反应体系温度升高到35℃搅拌30min。然后将138mL去离子水慢慢滴加进入反应体系,并且控制反应温度在98℃保持15min。紧接着将反应体系降温到室温,同时另外添加420mL去离子水与3mL 浓度为30%的H2O2。等反应混合物冷却到室温时,将物料在布氏漏斗中用去离子水洗涤至中性。得到的GO用超声分散在水中待用。GO纳米薄片的形貌通过原子力显微镜观察。GO纳米薄片的横向尺寸大约1.5μm(如图5中的a所示),其平均横向尺寸约1.2μm。得到的GO在水中分散性很好,在浓度为1.1wt%时即形成液晶形态。 GO is obtained by oxidation of graphite by Hummer's method. The specific method is as follows: Graphite flakes (3.0g, 1wt. relative mass content) and NaNO 3 (1.5g, 0.5 wt. relative mass content) were mixed uniformly at 0°C. Then add H 2 SO 4 (98%, 69mL) and mix well, and finally add KMnO 4 (9.0g, 3wt. relative mass content) slowly. When adding KMnO 4 , the temperature of the solution was controlled below 20°C. After adding KMnO 4 , the temperature of the reaction system was raised to 35°C and stirred for 30 minutes. Then 138 mL of deionized water was slowly added dropwise into the reaction system, and the reaction temperature was controlled at 98° C. for 15 min. Then the temperature of the reaction system was cooled to room temperature, and at the same time, 420 mL of deionized water and 3 mL of H 2 O 2 with a concentration of 30% were added. When the reaction mixture was cooled to room temperature, the material was washed with deionized water in a Buchner funnel until neutral. The obtained GO was dispersed in water by ultrasound for further use. The morphology of GO nanoflakes was observed by atomic force microscopy. The lateral size of GO nanoflakes is about 1.5 μm (as shown in a in Figure 5), and its average lateral size is about 1.2 μm . The obtained GO is well dispersible in water and forms a liquid crystal form at a concentration of 1.1 wt%.

实施例3  GO+NFC微米纤维的制备与表征 Example 3 Preparation and Characterization of GO+NFC Micron Fibers

GO+NFC微米纤维采用湿纺的方法制备,流程图如图3所示,即把纺丝液通过针管挤出到酒精凝固浴里析出,形成凝胶纤维,然后将凝胶纤维拉出凝固浴在空气中干燥。在干燥过程中,在微米纤维两端施加0.5N的作用力,以提高微米纤维的取向度。干燥后把微米纤维置于10wt% CaCl2的水溶液中浸渍1小时后重新干燥。以同样的方法,制备GO微米纤维以及NFC微米纤维做性能测试对比。 GO+NFC microfibers are prepared by wet spinning. The flow chart is shown in Figure 3, that is, the spinning liquid is extruded through a needle into an alcohol coagulation bath to form gel fibers, and then the gel fibers are pulled out of the coagulation bath. Air dry. During the drying process, a force of 0.5 N is applied to both ends of the microfibers to increase the degree of orientation of the microfibers. After drying, the microfibers were immersed in 10wt% CaCl 2 aqueous solution for 1 hour and re-dried. In the same way, GO micron fibers and NFC micron fibers were prepared for performance test comparison.

微米纤维的形貌用扫描电镜(SEM)观察:将待测样品进行真空干燥后,粘台、真空喷金。 The morphology of the micron fiber is observed by scanning electron microscope (SEM): after the sample to be tested is vacuum-dried, it is glued to the table and vacuum-sprayed with gold.

微米纤维的抗张强度以及弹性模量在DMA-800仪器上测量。测试模式为薄膜/纤维抗张强度测试模式。 The tensile strength and elastic modulus of the microfibers were measured on a DMA-800 instrument. The test mode is film/fiber tensile strength test mode.

将GO与NFC相结合的方法制备高强度微米纤维,结果如图4所示,其中,a为得到的GO+NFC混合微米纤维的结构示意图,在混合微米纤维中,GO与NFC都沿着纤维的轴向具有一定的排列。纤维间的结合力主要由氢键结合以及Ca2+引入而增加的离子键结合(b)。离子键的引入进一步提高了混合纤维的强度。 Combining GO and NFC to prepare high-strength microfibers, the results are shown in Figure 4, where a is a schematic diagram of the structure of the obtained GO+NFC mixed microfibers. In the mixed microfibers, both GO and NFC are along the fiber The axis has a certain arrangement. The binding force between fibers is mainly composed of hydrogen bonding and ionic bonding increased by the introduction of Ca 2+ (b). The introduction of ionic bonds further improves the strength of the hybrid fibers.

该方法中的纺丝液是GO与NFC按质量比 1:1配制好的浓度为1.1wt%的液晶溶液(如图5中的c所示)。同一浓度下,混合均匀的GO+NFC纺丝液,其液晶纹理结构与单独的GO液晶纹理结构明显不同。混合液的液晶纹理间隙明显小于GO液晶纹理间隙。将混合液自然干燥以后与偏光显微镜下观察可见GO具有明显的定向排列,这也证明了混合液的液晶相,如图5中的d。图5中,a为GO的AFM图,插入图为GO溶液,b为NFC的AFM图,插入图为NFC溶液,c为GO+NFC纺丝液的偏光显微镜图,插入图为GO+NFC纺丝液,d为GO+NFC纺丝液干燥后的偏光显微镜图。 The spinning solution in this method is a liquid crystal solution with a concentration of 1.1 wt% prepared by GO and NFC at a mass ratio of 1:1 (as shown in c in Figure 5). At the same concentration, the liquid crystal texture structure of the uniformly mixed GO+NFC spinning solution is obviously different from that of GO alone. The liquid crystal texture gap of the mixed solution is obviously smaller than that of GO liquid crystal texture. After natural drying of the mixed solution and observation under a polarizing microscope, it can be seen that GO has an obvious alignment, which also proves the liquid crystal phase of the mixed solution, as shown in d in Figure 5. In Fig. 5, a is the AFM image of GO, the insert is GO solution, b is the AFM image of NFC, the insert is NFC solution, c is the polarizing microscope image of GO+NFC spinning solution, the insert is GO+NFC spinning Silk solution, d is the polarizing microscope picture of GO+NFC spinning solution after drying.

湿纺法制备高强GO+NFC微米纤维时,先把GO+NFC纺丝液挤出到酒精凝固浴。当GO+NFC纺丝液接触酒精时,微米纤维表面会首先凝固出一层,然后慢慢通过溶剂交换,纤维内部的水也被置换出来,最终形成稳定的凝胶纤维。将凝胶纤维拉出凝固浴后,酒精便会挥发出来成为干燥的微米纤维。结果如图6所示,其中,a为湿纺法同时纺出4根微米纤维,b为由1mL纺丝液制备得到的纤维缠绕在直径1.5cm的钢柱上,c为两个纤维拧成的一根绳的SEM图,d为刚刚挤入凝固浴的凝胶纤维,e为凝胶纤维干燥了10s后以及f为干燥的纤维偏光显微镜图。图6中的a表示了一次可以挤出四根纤维,每根纤维可以有几米长,1mL纺丝液可以在几分钟内制备几十米纤维,b为1mL纺丝液喷出的微米纤维缠绕在钢柱上。这种方法制备的微米纤维其直径是可控的。通过改变针头直径的大小,便可得到直径在10-40μm不等的微米纤维,湿纺法得到的微米纤维具有良好的柔性,可以打结或者拧搓成绳,如图6中的c;为了提到纤维取向度和强度,纤维在干燥过程在其两端施0.5N的作用力。干燥过程中构成纤维的结构单元材料结合变得紧密,纤维的直径从凝胶纤维的大约80μm降低到最终成品纤维的10μm。偏光显微镜是观察物质是否具有取向性的有效手段,为表征纤维的取向性,把纤维至于偏光显微镜下观察,当纤维取向方向平行与偏振光时,只能看到黑色的背景。旋转纤维,偏光镜下纤维开始变得明亮,当纤维的方向与偏振光呈45°夹角时,纤维达到最亮的状态,图6中的d-f 纤维越来越亮,纹理越来越清晰,表明纤维的取向度越来越高。 When preparing high-strength GO+NFC micron fibers by wet spinning, the GO+NFC spinning solution is first extruded into an alcohol coagulation bath. When the GO+NFC spinning solution contacts alcohol, the surface of the micron fiber will first solidify to form a layer, and then slowly through the solvent exchange, the water inside the fiber is also replaced, and finally a stable gel fiber is formed. After the gel fibers are pulled out of the coagulation bath, the alcohol evaporates into dry micron fibers. The results are shown in Figure 6, in which, a shows that four micron fibers are spun simultaneously by wet spinning, b shows that the fibers prepared from 1 mL of spinning solution are wound on a steel column with a diameter of 1.5 cm, and c shows that two fibers are twisted into The SEM picture of a rope, d is the gel fiber just squeezed into the coagulation bath, e is the gel fiber after drying for 10s and f is the polarizing microscope image of the dried fiber. A in Figure 6 shows that four fibers can be extruded at a time, and each fiber can be several meters long. 1mL spinning solution can prepare tens of meters of fiber in a few minutes, and b is the micron fiber entanglement sprayed by 1mL spinning solution. on steel columns. The diameter of the micron fiber prepared by this method is controllable. By changing the diameter of the needle, micron fibers with a diameter ranging from 10 to 40 μm can be obtained. The micron fibers obtained by the wet spinning method have good flexibility and can be knotted or twisted into ropes, as shown in c in Figure 6; Referring to fiber orientation and strength, a force of 0.5 N is applied to both ends of the fiber during drying. During the drying process, the structural unit materials that make up the fibers become more compact, and the diameter of the fibers decreases from about 80 μm for the gel fibers to 10 μm for the final finished fibers. Polarizing microscope is an effective means to observe whether the material has orientation. In order to characterize the orientation of the fiber, observe the fiber under the polarizing microscope. When the orientation direction of the fiber is parallel to the polarized light, only a black background can be seen. When the fiber is rotated, the fiber begins to become bright under the polarizer. When the direction of the fiber is at an angle of 45° to the polarized light, the fiber reaches the brightest state. The d-f fiber in Figure 6 becomes brighter and the texture becomes clearer. It shows that the degree of fiber orientation is getting higher and higher.

作为参照样,以同样的方法制备了GO微米纤维与NFC微米纤维,如图7所示,其中,a为GO纺丝液的POM图,b-d为将GO纺丝液挤出到乙醇中,GO扩散为GO带,并且随着放置时间的增加,GO逐渐溶解到乙醇中,e为在1%NaOH乙醇凝固浴中制备GO微米纤维,f为GO微米纤维的POM图,g为NFC纺丝液的POM图,h为在乙醇凝固浴中制备NFC微米纤维,图中纤维使用蓝色染料染色,i为NFC微米纤维的POM图。图7中的a为GO纺丝液,在偏光镜下观察呈现明显的液晶相态。由于GO溶于乙醇,所以将GO纺丝液直接挤出到乙醇里时不能形成纤维,而是出现GO带。GO带强度差,不能保证能完整的从乙醇里捞出来;随着放置时间的增加,GO带逐渐溶解,最终溶于乙醇中(图7中的b-d)。为制备GO微米纤维,以1%NaOH乙醇溶液作为凝固浴。图7中的e显示,在1%NaOH乙醇凝固浴中可以形成GO微米纤维并且可以捞出来。得到的GO微米纤维在偏光纤维镜下观察(图7中的f),表明纤维具有较高的取向度。NFC不溶于乙醇,以乙醇为凝固浴可以很容易的得到NFC微米纤维。图7中的g为浓度1wt%的NFC纺丝液的POM图,表明NFC纺丝液为液晶相。将NFC纺丝液挤出到乙醇时,NFC纺丝液立即形成凝胶纤维,如图7中的h所示。图中NFC微米纤维以蓝色染料染色以在乙醇溶液中显示出NFC微米纤维。NFC具有自组装性能,在NFC微米纤维干燥过程中,NFC沿着纤维方向排列。对NFC微米纤维进行偏光显微镜观察显示:NFC微米纤维具有良好的取向度。 As a reference sample, GO microfibers and NFC microfibers were prepared in the same way, as shown in Figure 7, where a is the POM map of GO spinning solution, b-d is the extrusion of GO spinning solution into ethanol, GO Diffusion into GO belts, and with the increase of storage time, GO gradually dissolves into ethanol, e is the preparation of GO microfibers in 1% NaOH ethanol coagulation bath, f is the POM map of GO microfibers, g is the NFC spinning solution The POM map of , h is the NFC micron fiber prepared in the ethanol coagulation bath, the fiber in the figure is dyed with blue dye, and i is the POM map of the NFC micron fiber. A in Figure 7 is the GO spinning solution, which shows an obvious liquid crystal phase when observed under a polarizer. Since GO is soluble in ethanol, fibers cannot be formed when the GO spinning solution is directly extruded into ethanol, but GO bands appear. The strength of the GO band is poor, and it cannot be guaranteed to be completely removed from ethanol; as the storage time increases, the GO band gradually dissolves and finally dissolves in ethanol (b-d in Figure 7). To prepare GO microfibers, 1% NaOH ethanol solution was used as the coagulation bath. e in Figure 7 shows that GO microfibers can be formed in the 1% NaOH ethanol coagulation bath and can be fished out. Obtained GO microfibers were observed under a polarizing fiberscope (f in Fig. 7), which indicated that the fibers had a high degree of orientation. NFC is insoluble in ethanol, and NFC microfibers can be easily obtained by using ethanol as a coagulation bath. The g in Figure 7 is the POM diagram of the NFC spinning solution with a concentration of 1 wt%, indicating that the NFC spinning solution is a liquid crystal phase. When the NFC spinning solution was extruded into ethanol, the NFC spinning solution immediately formed gel fibers, as shown in h in Fig. 7. The NFC microfibers in the picture are dyed with a blue dye to reveal the NFC microfibers in ethanol solution. NFC has self-assembly properties. During the drying process of NFC microfibers, NFC is arranged along the fiber direction. Polarizing microscope observation of NFC microfibers shows that NFC microfibers have a good degree of orientation.

图8中的a-b为GO微米纤维、NFC微米纤维以及GO+NFC微米纤维的应力应变曲线,所得到的GO+NFC微米纤维的平均弹性模量以及平均抗张强度分别为20.6±0.9GPa和274.6±22.4MPa。高于纯NFC微米纤维(15.5±4.5GPa,139.1±28.7MPa)以及GO微米纤维(2.3±2GPa,84.0±2.8MPa)的强度。 a-b in Figure 8 are the stress-strain curves of GO microfibers, NFC microfibers and GO+NFC microfibers. The average elastic modulus and average tensile strength of the obtained GO+NFC microfibers are 20.6±0.9GPa and 274.6 ±22.4MPa. The strength is higher than that of pure NFC microfibers (15.5±4.5GPa, 139.1±28.7MPa) and GO microfibers (2.3±2GPa, 84.0±2.8MPa).

为进一步提高微米纤维的强度,对微米纤维进行Ca2+浸渍,在纤维中引入离子键,提高纤维间的结合强度。在浸渍过程中,纤维会发生回湿润胀,Ca2+进入到纤维内部,干燥之后变回形成离子键结合。图8中的b为GO微米纤维、NFC微米纤维以及GO+NFC微米纤维浸渍以后的应力应变曲线。浸渍以后,GO微米纤维的弹性模量以及抗张强度分别提高到9.7GPa和96.3MPa。NFC微米纤维的弹性模量以及抗张强度分别提高到20.7GPa和272MPa。GO+NFC微米纤维的弹性模量和抗张强度分别提高到31.6±2.5GPa和416.6±25.8MPa。GO+NFC微米纤维的弹性模量以及抗张强度最高可达到34.1GPa与 442.4MPa,断裂伸长率为2%。 In order to further improve the strength of the microfibers, the microfibers were impregnated with Ca 2+ , and ionic bonds were introduced into the fibers to increase the bonding strength between the fibers. During the impregnation process, the fiber will re-wet and swell, and Ca 2+ will enter the interior of the fiber, and after drying, it will change back to form an ionic bond. b in Figure 8 is the stress-strain curve after impregnation of GO micron fiber, NFC micron fiber and GO+NFC micron fiber. After impregnation, the elastic modulus and tensile strength of GO microfibers increased to 9.7 GPa and 96.3 MPa, respectively. The elastic modulus and tensile strength of NFC microfibers were increased to 20.7GPa and 272MPa, respectively. The elastic modulus and tensile strength of GO+NFC microfibers were increased to 31.6 ± 2.5 GPa and 416.6 ± 25.8 MPa, respectively. The elastic modulus and tensile strength of GO+NFC micron fibers can reach up to 34.1GPa and 442.4MPa, and the elongation at break is 2%.

实施例4GO+NFC微米纤维的用途 The purposes of embodiment 4GO+NFC micron fiber

GO+NFC微米纤维具有优异的机械性能,可用于超强结构材料的制备,结果如图9所示,a为用一根GO+NFC微米纤维提起质量为12.5g的磁力搅拌棒,b为穿在针上的GO+NFC微米纤维,c-d为将GO+NFC微米纤维在布上缝制不同的图案,e为使用GO+NFC微米纤维编织网,为GO+NFC微米纤维编织的网可以任意弯曲,为GO+NFC微米纤维网支撑起磁力搅拌棒。形象的表示了GO+NFC微米纤维的强度。图中为用一根直径大约80μm的GO+NFC微米纤维系住并提起质量为12.5g的磁力搅拌棒。GO+NFC微米纤维不仅具有优异的机械性能,同时具有良好的柔韧性,可以像线一样被缝在衣物上。显示GO+NFC微米纤维可穿在普通针上,在衣物上缝制不同的图案。显示GO+NFC微米纤维可以被编织成具有一定强度的网。此网可以被任意弯曲甚至折叠,也可以支撑100倍于本身质量的重物。GO+NFC微 米纤维密度低,强度高,是制备高强度材料的良好选择。 GO+NFC micron fibers have excellent mechanical properties and can be used in the preparation of super-strength structural materials. The results are shown in Figure 9, a is a 12.5g magnetic stirring bar lifted by a GO+NFC micron fiber, b is the GO+NFC micron fiber on the needle, c-d is sewing different patterns of GO+NFC micron fiber on the cloth, e is using GO+NFC micron fiber to weave the net, the net woven for GO+NFC micron fiber can be bent arbitrarily , supporting a magnetic stirring bar for the GO+NFC micron fiber web. It vividly shows the strength of GO+NFC micron fiber. In the figure, a GO+NFC microfiber with a diameter of about 80 μm is tied and lifted to a magnetic stirring bar with a mass of 12.5 g. GO+NFC micron fibers not only have excellent mechanical properties, but also have good flexibility, and can be sewn on clothes like threads. It shows that GO+NFC micron fibers can be worn on ordinary needles to sew different patterns on clothes. It is shown that GO+NFC microfibers can be woven into a mesh with certain strength. This net can be bent or even folded arbitrarily, and can also support a weight 100 times its own mass. GO+NFC micro fiber has low density and high strength, which is a good choice for the preparation of high-strength materials.

实施例5  导电微米纤维的制备与表征 Example 5 Preparation and Characterization of Conductive Micron Fibers

导电GO+NFC微米纤维(c(GO+NFC))的制备通过对GO+NFC前驱体纤维进行炭化得到。GO+NFC前驱体纤维的炭化在95%氩气与5%氢气混合气氛中进行。升温程序如下:先从室温到以30℃/h的升温速率升到400℃,之后以200℃/h的升温速率升到1000℃,最后在1000℃下保温2h。NFC与GO纤维以同样程序处理,作为对比样。 Conductive GO+NFC microfibers (c(GO+NFC)) were prepared by carbonizing GO+NFC precursor fibers. The carbonization of GO+NFC precursor fibers was carried out in a mixed atmosphere of 95% argon and 5% hydrogen. The heating program is as follows: first from room temperature to 400°C at a rate of 30°C/h, then to 1000°C at a rate of 200°C/h, and finally at 1000°C for 2 hours. NFC and GO fibers were treated with the same procedure as a comparison sample.

微米纤维的形貌以SEM表征,将待测样品进行真空干燥后,粘台、真空喷金。 The morphology of the micron fibers is characterized by SEM. After the sample to be tested is vacuum-dried, it is bonded and vacuum-sprayed with gold.

炭化纤维的碳结构以TEM表征。TEM制样时,先将炭化纤维超声分散在水溶液中,然后滴10μL溶液在炭网上,多余的液体用滤纸吸走。 The carbon structure of the carbonized fibers was characterized by TEM. When preparing samples for TEM, ultrasonically disperse the carbonized fibers in the aqueous solution, then drop 10 μL of the solution on the carbon mesh, and absorb the excess liquid with filter paper.

微米纤维的导电率通过测试微米纤维的I-V曲线得到。用银胶把导电微米纤维两端固定,微米纤维长度与平均直径以光学显微镜测试。在计算微米纤维导电性时,把微米纤维视为标准的实体圆柱。 The conductivity of the micron fiber is obtained by testing the I-V curve of the micron fiber. The two ends of the conductive microfibers were fixed with silver glue, and the length and average diameter of the microfibers were tested with an optical microscope. When calculating the conductivity of microfibers, treat microfibers as standard solid cylinders.

使用炭化的方法制备高导电性的微米纤维,结果如图9所示,其中,a-b为显示炭化后NFC由纤维状变为球状,c-d为显示含有GO的NFC炭化后,只有片状材料,球状材料消失,e为炭化后GO+NFC纤维的结构示意图。由图9可知,a-b为NFC炭化前后的形貌变化,图中显示纤维状的NFC在炭化形成球状碳颗粒,c-d是GO+NFC炭化前后示意图,表明炭化后没有球状的NFC炭化产物,只存在类似GO形貌的碳化产物,e示意了炭化后c(GO+NFC)微米纤维的形貌。结构单元材料在纤维中沿着纤维的轴向排列,微米纤维内部由于炭化过程中得收缩以及结构单元材料的重排产生中空结构。 Using the carbonization method to prepare high-conductivity micron fibers, the results are shown in Figure 9, where, a-b shows that after carbonization, the NFC changes from fibrous to spherical, and c-d shows that after carbonization of NFC containing GO, there are only flake materials, spherical The material disappears, and e is a schematic diagram of the structure of GO+NFC fibers after carbonization. It can be seen from Figure 9 that a-b are the morphology changes before and after NFC carbonization. The figure shows that the fibrous NFC is carbonized to form spherical carbon particles. Carbonization products with similar GO morphology, e shows the morphology of c(GO+NFC) microfibers after carbonization. The structural unit materials are arranged in the fiber along the axial direction of the fiber, and the inside of the micro-fibers has a hollow structure due to the shrinkage during the carbonization process and the rearrangement of the structural unit materials.

碳化后的SEM图如图10所示,其中,a-b为炭化后NFC纤维的SEM图,c-d为炭化后GO纤维的SEM图,e-f为炭化后GO+NFC纤维的SEM图。炭化后的NFC微米纤维,其形貌如图10的a-b所示,纤维的表面由许多直径大约1μm的炭微球组成,NFC微米纤维的平均导电率为33S/cm,与碳纤维的导电率相似。炭化后的GO微米纤维变得粗糙多孔,但GO仍以片状形式存在(如图10的c-d)。炭化GO微米纤维的平均导电率为137S/cm,高于炭化NFC微米纤维。图10的e-f为炭化后GO+NFC微米纤维形貌,结构与炭化GO微米纤维相似:纤维为多空结构,没有炭化NFC微球的存在。因为GO是NFC炭化的模型剂,使得NFC炭化材料涂布在炭化GO片上。这一碳涂层可修补热处理GO时产生的空位与拓扑缺陷,从而提高导电性。另外这一碳涂层也起到碳胶的作用,将炭化GO片连接起来,增加片与片中间的接触,降低电子传输阻力,进一步提高纤维的导电性。 The SEM image after carbonization is shown in Figure 10, where a-b is the SEM image of NFC fiber after carbonization, c-d is the SEM image of GO fiber after carbonization, and e-f is the SEM image of GO+NFC fiber after carbonization. The morphology of NFC microfibers after carbonization is shown in Figure 10 a-b. The surface of the fibers is composed of many carbon microspheres with a diameter of about 1 μm. The average conductivity of NFC microfibers is 33 S/cm, which is similar to that of carbon fibers. . The carbonized GO microfibers become rough and porous, but GO still exists in the form of flakes (c-d in Figure 10). The average conductivity of carbonized GO microfibers is 137 S/cm, which is higher than that of carbonized NFC microfibers. Figure 10 e-f shows the morphology of GO+NFC microfibers after carbonization, and the structure is similar to that of carbonized GO microfibers: the fibers have a porous structure without carbonized NFC microspheres. Because GO is a model agent for NFC carbonization, the NFC carbonization material is coated on the carbonized GO sheet. This carbon coating repairs the vacancies and topological defects generated during heat treatment of GO, thereby improving the conductivity. In addition, this carbon coating also acts as a carbon glue, connecting the carbonized GO sheets, increasing the contact between the sheets, reducing the electron transmission resistance, and further improving the conductivity of the fiber.

炭化后c(GO+NFC)纤维的平均导电率为649±60 S/cm,是现今报道的由石墨、GO以及GO复合物制备的导电纤维的最导电率。图11为c(GO+NFC)微米纤维室温下的I-V曲线,测试纤维长35mm,纤维平均直径为18μm。 The average conductivity of c(GO+NFC) fibers after carbonization is 649±60 S/cm, which is the highest conductivity reported so far for conductive fibers prepared from graphite, GO and GO composites. Figure 11 is the I-V curve of c(GO+NFC) micron fibers at room temperature, the test fiber length is 35mm, and the average fiber diameter is 18μm.

实施例5  导电微米纤维的应用 Example 5 Application of Conductive Micron Fibers

柔性电器以及可穿戴电器因其易于携带、集成性好备受关注。作为此类电子设备的主要构成部分,对高导电性纤维的研究越来越多,因为它容易被织到纺织产品中或者集成到其他机构中。实施例4所制备的导电纤维在可穿戴纳米发电机,超级电容器,电池,致动器,以及柔性太阳能电池上广泛应用。例如:将c(GO+NFC)微米纤维作为电极材料用于钠离子电池的组装,结果显示:第一个循环的效率较低,电池第二个循环的放电容量为317.3mAh/g,效率为62.2%。在63个循环以后,电池的放电容量为312mAh/g与第二个循环的放电容量基本相同。这个良好的电化学反应主要归功于纤维的高导电性。同时c(GO+NFC)微米纤维表现出一定的柔韧性,在柔性、可穿戴电子设备的制备上具有应用潜能。 Flexible electrical appliances and wearable electrical appliances have attracted much attention because of their portability and good integration. As a major building block of such electronic devices, highly conductive fibers are being studied more and more because of their ease of being woven into textile products or integrated into other mechanisms. The conductive fibers prepared in Example 4 are widely used in wearable nanogenerators, supercapacitors, batteries, actuators, and flexible solar cells. For example: using c(GO+NFC) micron fibers as electrode materials for the assembly of sodium-ion batteries, the results show that the efficiency of the first cycle is low, the discharge capacity of the second cycle of the battery is 317.3mAh/g, and the efficiency is 62.2%. After 63 cycles, the discharge capacity of the battery was 312 mAh/g which was basically the same as that of the second cycle. This good electrochemical reaction is mainly attributed to the high conductivity of the fibers. At the same time, c(GO+NFC) microfibers exhibit certain flexibility, which has potential application in the preparation of flexible and wearable electronic devices.

Claims (7)

1. prepare a method for superconduct micrometer fibers, it is characterized in that, comprise the following steps:
1) TEMPO oxycellulose is once by preparing NFC after microfluidizer;
2) Hummer ' s method is adopted to be oxidized graphite and to obtain GO;
3) preparation of high strength micrometer fibers: spinning solution is expressed in alcohol coagulating bath by needle tubing and separates out, form gelatinous fibre, then gelatinous fibre is pulled out coagulating bath dry in atmosphere; In dry run, apply the active force of 0.5N at micrometer fibers two ends, to improve the degree of orientation of micrometer fibers; After drying, micrometer fibers is placed in 10wt% CaCl 2the aqueous solution in dipping again dry after 1 hour;
4) charing is carried out to high strength micrometer fibers and obtain conduction GO+NFC micrometer fibers.
2. the method preparing superconduct micrometer fibers according to claim 1, is characterized in that: in step 1): the over dry softwood pulp that 5g is not dried and 78mg TEMPO, 514mg NaBr fully mix; Reaction adds initiation by 30mL 12%NaClO, and reacts under stirring at room temperature; The pH value of system controls to be stabilized in 10.5 by NaOH; The end until system interior residue NaClO reacts completely; Reacted slurry is clean by filtration washing, to pH in neutral; The concentration fiber obtained being made into 1% is processed under 5 ~ 25KPa pressure by microfluidizer; Obtain transparent nanofiber element dispersion liquid; Dispersion liquid storage and 4 DEG C of refrigerators.
3. the method preparing superconduct micrometer fibers according to claim 1, is characterized in that: step 2) in: by 3.0g graphite flakes, 1.5g NaNO 3mix at 0 DEG C; Then 69mL 98%H 2sO 4add mixing and stirring, finally slowly add 9.0g KMnO 4; Add KMnO 4time solution temperature control, lower than 20 DEG C, to add KMnO 4after temperature of reaction system is elevated to 35 DEG C and stirs 30min; Then 138mL deionized water is slowly dripped and enter reaction system, and control reaction temperature at 98 DEG C of maintenance 15min; And then reaction system is cooled to room temperature, interpolation 420mL deionized water and 3mL concentration are the H of 30 % in addition simultaneously 2o 2; Deng reactant mixture cool to room temperature time, material is spent in Buchner funnel deionized water to neutral; The GO ultrasonic disperse obtained is stand-by in water.
4. the method preparing superconduct micrometer fibers according to claim 1, is characterized in that: in step 3), and described spinning solution is the concentration that GO and NFC mass ratio 1:1 prepares is the liquid crystal solution of 1.1wt%.
5. the method preparing superconduct micrometer fibers according to claim 1, is characterized in that: in step 4), and the charing of high strength micrometer fibers is carried out in 95% argon gas and 5% hydrogen mixed gas atmosphere; Heating schedule is as follows: be first raised to 400 DEG C from room temperature to the heating rate of 30 DEG C/h, be raised to 1000 DEG C afterwards, finally at 1000 DEG C, be incubated 2h with the heating rate of 200 DEG C/h.
6. the superconduct micrometer fibers that the method preparing superconduct micrometer fibers described in any one of claim 1-5 obtains.
7. superconduct micrometer fibers according to claim 6 is as the application of conductive material.
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