Ordered Silica Nanoparticles Grown on a Three-Dimensional Carbon

Subscriber access provided by UNIV OF CAMBRIDGE

Article

Ordered Silica Nanoparticles Grown on a ThreeDimensional Carbon Fiber Architecture Substrate with Siliconborocarbonitride Ceramic as a Thermal Barrier Coating Guangdong Zhao, Ping Hu, Shanbao Zhou, Guiqing Chen, Yumin An, Yehong Cheng, Jiadong An, Xinghong Zhang, and Wenbo Han ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.5b12140 • Publication Date (Web): 22 Jan 2016 Downloaded from http://pubs.acs.org on January 23, 2016

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

ACS Applied Materials & Interfaces is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 37

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Applied Materials & Interfaces

Ordered

Silica

Three-Dimensional

Nanoparticles Carbon

Grown

Fiber

on

a

Architecture

Substrate with Siliconborocarbonitride Ceramic as a Thermal Barrier Coating Guangdong Zhao*, Ping Hu, Shanbao Zhou, Guiqing Chen, Yumin An, Yehong Cheng, Jiadong An, Xinghong Zhang*, Wenbo Han* National Key Laboratory of Science and Technology on Advanced Composites in Special Environments Centre for Composite Materials and Structures, Harbin Institute of Technology, Harbin 150080, China

Abstract Hierarchical structure consisting of ordered silica nanoparticles grown onto carbon fiber (CF) has been fabricated to improve the interfacial properties between the CFs and polymer matrix. In order to improve the reactivity of CFs, their surface was modified using poly(1,4-phenylene diisocyanate) (PPDI) via in-situ polymerization, which also resulted in the distribution of numerous isocyanate groups on the surface of CFs. Silica nanoparticles were modified on the interface of CF-PPDI by chemical grafting method. The microstructure, chemical composition and interfacial properties of CFs with ordered silica nanoparticles were comprehensively investigated by scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy. Results indicated an obvious increase in the interfacial shear strength, compared to those of CF precursor, which was attributed to silica nanoparticles interacting with the epoxy resin. Furthermore, siliconborocarbonitride

ACS Paragon Plus Environment


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 2 of 37

(SiBCN) ceramic was used as thermal barrier coating to enhance three-dimensional carbon

fiber

architecture

substrate

antioxidant

and

ablation

properties.

Thermogravimetric results show that the thermal stability of the CF with SiBCN ceramic layer has a marked increase at high temperature.

Keywords: carbon fiber, silica nanoparticles, chemical grafting, interfacial properties, thermal stability

1. Introduction Carbon fiber (CF) reinforced composites have attracted significant attention for a wide range of applications in aerospace, automotive, manufacturing sport equipment, civil engineering, and numerous industrial fields. This is attributed to their excellent mechanical properties such as high specific strength and modulus, high rupture toughness, high rigidity, good thermal shock resistance, high heat of ablation, and chemical resistance.1-6 However, the excellent properties of CF reinforced composites depend not only on the performances of the CFs and matrix, but also closely related to the interface between the fiber and the surrounding polymer matrix.7-10 Despite that CF has become an indispensable material of construction in many different industries due to its high strength, low density, and good electrical/thermal conductivity. However, the commercial CFs commonly have smooth and inert surfaces, which lead to weak cohesive forces in the interface of fibers and matrix. Therefore, creation of a good interface of CF and matrix is highly desirable to prevent the performance degradation of the composites. Thus, the interface between the CFs and matrix remains an important area of research and it plays a significant role in determining the


Page 3 of 37

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


macroscopic shear, transverse, and out of plane properties of a composite.10-11 It is well known that the interface properties of CFs are primarily related to their microstructure and chemical bonds.12-15 The CFs without surface treatment have low surface energy and roughness. Besides the outer layer, the CFs mainly consist of graphitic microcrystals. Although the graphitic microcrystals are beneficial to strengthen the mechanical properties of CFs, it provides minimal chemical or physical interaction with the polymer matrix. The physical and chemical treatments on the surface of the CF were used to increase the surface area and surface functional groups, with the objective of enhancing the fiber–matrix interactions.16-21 Chemical modification techniques have been used extensively to improve interfacial adhesion in CFs and polymer matrix and to aid in effective load transfer; thus they have been a focus of academic research. Furthermore, chemical modification techniques also exhibit good prospects in industrial applications to fabricate a new generation of high-performance CF reinforced composites.22-24 In general, these techniques mainly include chemical grafting modification and chemical vapor deposition (CVD). Both the methods include the grafting of the micometer and nanometer scale materials such as carbon nanotubes (CNTs), graphene oxide (GO), and metallic oxide nanoparticles on the surface of the CFs.25-33 Direct growth of the CNTs onto the surface of the CFs is one of the most frequently used approaches for their modification. Recently, the hierarchical structuring of CFs using CNTs, grown directly on the surfaces of CFs, was studied comprehensively. The study demonstrated that the interfacial shear strength (IFSS) of CFs in a polymer matrix was



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 4 of 37

significantly improved by 25–175%.34-40 However, these methods involved following important limitations: the catalyst such as nickel and cobalt and their compounds polluted the CFs interface and high temperature deposition condition led to the degradation of the CF surface, resulting in deteriorated tensile strength. In contrast, the chemical grafting method involves relatively mild reaction conditions and it is capable of improving the interfacial reaction activity of the CFs. Grafting CNTs onto the surface of the CFs through chemical reaction has also been investigated extensively. CNTs are grafted onto the surface of CFs by chemical reactions using poly(amido amine) and polyhedral oligomeric silsesquioxanes as coupling agents.41-43 Silica nanoparticles as an important inorganic nanomaterial are often used to fabricate organic/inorganic hybrid materials, which have attracted substantial academic and industrial interest and have been employed in a variety of applications.44-48 Introducing silica nanoparticles can combine the advantages of the inorganic nanomaterial (e.g., rigidity, high specific surface area and thermal stability) and other functional materials.49-53 At present, silica nanoparticle grafting onto CFs by chemical grafting method has rarely studied, so the introduction of silica nanoparticles is expected to improve the interfacial properties of carbon fiber reinforced composites effectively. In the past decades, polymer derived ceramics have been expanded and are prepared via solid-state thermolysis of preceramic polymers. Numerous important engineering

fields

suitable

for

potential

application

of

PDCs

include

high-temperature-resistant materials (energy materials, automotive, aerospace), hard


Page 5 of 37

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


materials, and it also have many potential applications in areas such as coating technologies, high temperature electronics and optoelectronics.54-56 Then, a large number of preceramic polymer classes have been developed, which act as precursors for the fabrication of mainly silicon (Si)-based advanced ceramics. Among them, amorphous SiBCN materials have attracted great interest due to their combination of an excellent high temperature stability (up to 2000 °C) and oxidation resistance (up to 1500 °C) with stability of useful functional properties up to these very high temperatures in extreme heat environment.

57-59

Moreover, siliconborocarbonitride

(SiBCN) preceramic polymers owing to their multiple compositions have been used as polymer matrix to fabricate CF reinforced polymer composites. The preceramic precursors synthesis process is made up of two parts: low temperature polymerization and cross-linking in high temperature (100–350 °C). Functional ceramic is achieved after pyrolysis at high temperatures (1000–1600 °C) in an inert atmosphere. The structure and composition of preceramic polymer can be designed on the molecular level and it will decide the composition and final structure of ceramic. Lee et al. synthesized SiBCN preceramic polymers using three monomers, trichlorosilane (HSiCl3), boron trichloride (BCl3), and hexamethydisilazane (HMDZ). The preceramic polymers were pyrolysis of at 1600 °C and converted to SiBCN ceramics via phase transformation, the ceramic has a good thermal stability in high temperature.60 Due to SiBCN ceramics with good thermal property and operability, it can be used as thermal barrier coating material to protect the carbon fiber substrate damaging in elevated temperature.



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

In this study, 1,4-phenylene diisocyanate (PDI) was used as the coupling agent to prepare CF-PPDI-g-nanosilica hierarchical structure via in situ polymerization and chemical grafting process. First, triethylamine was used to catalyze the nucleophilic addition reaction between isocyanate groups and hydroxyl groups of acidified CF, and then poly-PDI (PPDI) polymer layer was formed on the surface of CFs by addition polymerization of PDI as a monomer. PPDI itself contains numerous unreactive isocyanate groups, which could be used as a novel macromolecule coupling agent capable of reacting efficiently with silica nanoparticles. Then SiBCN preceramic polymers were synthesized on the surface of modified carbon fiber substrate. After pyrolysis at 1400 °C in inert atmosphere, SiBCN preceramic polymers converted to SiBCN ceramics coating. The amorphous ceramic coating could effectively protect the carbon fiber substrate in high temperature. The microstructure and interfacial properties of modified carbon fiber substrate were discussed in detail.

2. Experimental section 2.1. Materials Carbon fiber samples (6.8 µm) were purchased from Tianniao Company (Jiangsu, China). 1,4-Phenylene diisocyanate (98%), triethylamine (99%), and nanosilica (15 ± 5 nm) were purchased from Aladdin Industrial Corporation. (3-aminopropyl)triethoxysilane (99%), (3-glycidyloxypro-pyl)trimethoxysilane (98%), boron trichloride solution (BCl3, 1.0 M in methylene chloride), trichlorosilane (HSiCl3, 99%), and hexamethyldisilazane (HDMZ, 99.9%) were purchased from J&K Scientific Ltd. Other chemicals were of analytical grade and used as received without further


Page 6 of 37

Page 7 of 37

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


purification. 2.2. Synthesis of functionalized CF using isocyanate species In a typical reaction, CF was added to acetone with magnetic stirring at 70 °C for 48 h. Subsequently, the contents were filtered and thoroughly washed with acetone. After drying under vacuum, CF and concentrated nitric acid were added into a round bottomed flask, and the mixture was stirred at 80 °C for 4 h. The solid products were dried under vacuum until constant weight was obtained. PDI (0.5 g), toluene (50 mL), and acidified CF were taken in a round bottomed flask and then triethylamine was added as a catalyst. The reaction mixture was allowed to stir at 40 °C for 5 h. The product so-obtained was filtered and thoroughly washed with toluene. The solid sample was collected and dried under vacuum until constant weight. 2.3. Preparation of nanosilica grafted onto CF (CF-PPDI-g-nanosilica) In a typical synthesis, nanosilica (0.1 g) was taken in a round bottomed flask and dispersed in dioxane (100 mL) for 6 h. Subsequently, as-obtained nanosilica dispersion (10 mL), isocyanate functionalized CF, and triethylamine were taken in a round bottomed flask. The reaction mixture was allowed to stir at 40 °C for 24 h. The so-obtained product was filtered and thoroughly washed with ethanol. The solid sample was collected and dried under vacuum until constant weight. 2.4. Preparation of SiBCN preceramic polymer coating on CF-PPDI-g-nanosilica In a typical reaction, CF-PPDI-g-nanosilica, BCl3, HSiCl3, and HDMZ were successively added to a round bottomed flask, and the mixture was degassed with nitrogen for 30 min. The reaction mixture was magnetically stirred at 70 °C for 3 h



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

and then heated to 200 °C for 3 h. The reaction product was distilled under reduced pressure, then the solid sample was collected, and dried under vacuum until constant weight was acquired which resulted in the formation of the desired product CF-PPDI-g-nanosilica /SiBCN preceramic polymer. 2.5. Preparation of CF-PPDI-g-nanosilica/SiBCN ceramics hierarchical structure Pyrolysis of CF-PPDI-g-nanosilica /SiBCN ceramic composites led to the formation of SiBCN ceramics. CF-PPDI-g-nanosilica /SiBCN preceramic polymer was first heated in nitrogen atmosphere from 25 to 900 °C at a heating rate of 10 °C min−1. The temperature was held constant at 900 °C for 30 min, and then the polymer was heated to 1400 °C, and held for 1 h in a silicate tube furnace. The contents were cooled down to room temperature which resulted in the formation of the composites. 2.6. Characterization The morphology of the fabricated materials was investigated by scanning electron microscopy (SEM, Sirion 200 FEI Netherlands). The elemental compositions and chemical binding states were analyzed by X-ray photoelectron spectroscopy (XPS, Escalab 250, USA) and Fourier transform infrared spectroscopy (FTIR, Perkin–Elmer 2000, USA) using KBr disks. The thermal stability of the materials was characterized by thermogravimetric analyses (TGA, TA Instruments TGA 2050, USA) at a rate of 10 °C min-1 under nitrogen. Atomic force microscopy (AFM) images were collected using a Dimension Icon AFM system (Bruker) in tapping mode and the surface roughness was extracted from topography images. Nitrogen sorption measurements were performed using a Micromeritics 2020 ASAP instrument at 77 K. The surface


Page 8 of 37

Page 9 of 37

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


area values were calculated using the Brunauer−Emmett−Teller (BET) method. Single fiber pull-out tests were carried out on an interfacial strength evaluation instrument (Tohei Sanyon Corporation, Japan) at a crosshead displacement rate of 0.5 µm s-1. The values of interfacial shear strength (IFSS) between the carbon fibers and the matrix were calculated using equation below: ‫= ܵܵܨܫ‬

‫ܨ‬௠௔௫ ߨ ∙ ݀௙ ∙ ݈௘

Here, Fmax is the maximum load recorded, df is the carbon fiber diameter, and le is the embedded length. A carbon fiber monofilament was fixed to a metal holder with adhesive tape. Epoxy resin mixture were poured carefully onto the carbon fiber monofilament with the embedded length of 40–60 mm using a fine-point applicator. The specimens were cured at 80 °C for 2 h, then at 150 °C for 4 h.

3. Results and discussion This study primarily aimed to facilely synthesize functionalized CFs with excellent interfacial properties by in-situ polymerization and chemical grafting process. Figure 1 shows that CF-PPDI-g-nanosilica hierarchical structure contains numerous isocyanate groups and silica nanoparticles, which can significantly improve the interfacial properties of the CF by increasing the surface roughness and mechanical interlocking.



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Figure 1. Schematic illustration of the preparation CF-PPDI-g-nanosilica/siliconboro-carbonitride ceramic hierarchical structure.

Page 10 of 37

process

for

First, the organic chemistry techniques and in situ polymerization method were integrated to form a layer of PPDI polymer consisting of a large number of unreactive isocyanate groups. Second, silanol groups on the surface of nanosilica were allowed to react with isocyanate functionalized CFs (Figure 2). CFs were oxidized in concentrated nitric acid, which resulted in the formation of large number of hydroxyl, carboxyl, and epoxy groups on the surface of CFs. PDI as an aromatic isocyanate coupling agent exhibits higher reactivity toward hydroxyl and carboxyl groups, compared to aliphatic isocyanate agents.

Figure 2. Schematic representation of the reaction process for the formation of CF-PPDI-g-nanosilica hierarchical structure.


Page 11 of 37

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Initially, PDI mainly reacts with hydroxyl groups present on the surface of acidified CFs. The reaction mechanism of acidified CF with PDI is shown in Figure 3. The reaction between isocyanate and active hydrogen containing functional groups (hydroxyl groups) is efficient and quantitative under certain reaction conditions (catalyst, temperature). The electronegativity and energy absorption ability of nitrogen and oxygen atoms are higher than those of carbon atom due to the presence of highly unsaturated bonds in isocyanate groups. Consequently, the carbon atom becomes more susceptible to attack by nucleophilic species, thus the isocyanate groups easily react with the hydroxyl groups via nucleophilic addition, and the reactivity of hydroxyl group outclasses that of the carboxyl group as indicated by the comparative studies performed on the surface of acidified CFs.

Figure 3. The reaction mechanism of acidified CF with PDI.

One of the important characteristics of the isocyanates is the intensive tendency of self-polymerization. Under the influence of the nucleophilic species, the lone pair of electrons present on the carbon atoms of the isocyanates is shifted to the nitrogen atom, which results in the formation of a complex compound. Subsequently, the complex reacts with the other molecule of isocyanate via addition reaction to form stable tripolymer and cross-linked polymer under certain optimized and specified conditions (Figure 4).



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Figure 4. The oligomerization/polymerization of PDI molecule.

Following the reaction of isocyanate species with hydroxyl groups present on the surface of acidified CF, monomer PDI polymerized to form the polymer PPDI on the surface of the CF. The polymer PPDI contained numerous unreactive isocyanate groups, which could be useful in the chemical grafting process. CF precursor consisted of highly oriented graphite sheets; therefore, its surface was smooth and had chemical inertia. Further, the surface of CF was treated with acetone and concentrated nitric acid, which led to the appearance of a few defects, resulting in a partial decrease in the mechanical properties of the CF. However, the PPDI layer surrounding the CF could effectively repair the defects, leading to a significant improvement in its surface reactivity. IR analysis was used to monitor the changes occurring in the chemical bonds during the isocyanate self-polymerization, and the target structures were clearly identified. Various covalent bonds of PDI and the polymer PPDI are shown in Figure 5. A very intense band observed at 2319 cm−1 is indicative of anti-symmetric stretching vibration absorption peak of isocyanate groups (–N=C=O). Three additional bands are clearly identified at 1549, 1508, and 1407 cm−1, which are attributed to C=C bond on the benzene. As shown in Figure 5b and 5c, a strong


Page 12 of 37

Page 13 of 37

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


stretching vibration absorption bands observed at 3165–3450 cm−1 is attributed to the characteristic group frequencies of C–N hexatomic ring belonging to a cyanurate core, formed during the self-polymerization of isocyanates. This result shows that PDI polymerizes efficiently to form a polymer with triethylamine as the catalyst. Moreover, the absorption peak intensity of isocyanate groups at 2319 cm−1 (Figure 5c) is significantly higher than that for isocyanate groups shown in Figure 5b, thus the result demonstrates that the content of isocyanate groups increases with increasing monomer concentration.

Figure 5. FTIR spectra of a) PDI, b) PPDI-1, and c) PPDI-2. Reaction conditions: b) M0 [PDI] = 2.5 mg mL−1, in toluene at 40 °C for 5 h; c) M0 [PDI] = 5 mg mL−1, in toluene at 40 °C for 5 h.

The thermal gravimetric analysis–differential thermal gravity (TGA–DTG) technique in a flowing nitrogen atmosphere was utilized to investigate the weight loss of the PPDI polymer at high temperature. Simultaneously, PDI was used as reference substance. The TG and DTG curves of the PPDI-1 and PPDI-2 polymers are shown in Figure 6. The coupling agent PDI is stable during its initial heating from 25 to 100 °C,



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

and then rapid loss in its weight is observed until decomposition temperature (212 °C). In contrast, the PPDI-1 and PPDI-2 polymers are stable during their initial heating from 25 to 204 °C, and the weight remains ca. 98.8%. The DTG curves show that the PPDI-1 and PPDI-2 polymers do not exhibit significant drop in their mass until 204 °C. Further, the thermal decomposition of the PPDI polymer can be divided into two stages. The first stage can be ascribed to the decomposition of isocyanate tripolymer from 25 to 294 °C. The DTG results show that the decomposition temperature of PPDI-1 and PPDI-2 is identical up to 254 °C. The second stage is mainly attributed to the cross-linked polymer decomposition in the temperature range 294 to 800 °C. The decomposition temperature of PPDI-1 and PPDI-2 polymer reaches to 377 and 385 °C in this stage, respectively. It is attributed to the difference in monomer concentration of PPDI-1 and PPDI-2 polymers. Higher monomer concentration leads to higher degree of polymerization; thus the thermal stability of high molecular weight polymer is better than that of the low molecular weight polymer at high temperature. Furthermore, the TG curves show that the weight loss of PPDI-2 is lower than that of PPDI-1, which also demonstrates that PPDI-2 has higher degree of polymerization. Therefore, the abovementioned results indicate that PDI can effectively polymerize on the surface of acidified CF to form PPDI polymer layer.


Page 14 of 37

Page 15 of 37

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 6. TG and DTG curves of a) PDI, b) PPDI-1, and c) PPDI-2 at a heating rate of 10 °C min−1 in nitrogen from 25 to 800 °C.

Nanosilica has an extremely large surface area and smooth nonporous surface. The structure of nanosilica shows a three-dimensional network with uniform distribution of numerous silanol groups on the nanosilica surface. Isocyanate groups can efficiently react with silanol groups by nucleophilic addition under certain conditions such as use of appropriate catalyst. In this study, nanosilica grafted carbon produced via chemical grafting method was extensively investigated, and the synthetic route is depicted in Figure 2. Isocyanates functionalized CF-PPDI hierarchical structure, used



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

as an active substrate, reacted with the silanol groups on the surface of nanosilica. Subsequently, nanosilica was connected to the CF through a strong chemical bond. On completion of the grafting reaction, the residual isocyanates and silica nanoparticles could significantly improve the interfacial properties of CF. IR analysis was performed to identify the bonds formation of the CFs in different processes with the objective of identifying the expected bond after modification. The FTIR spectrum of the acidified CF is shown in Figure 7a, which indicates the formation of various covalent bonds in the acid-treated CF. The absorption peak attributable to the stretching vibration of the OH unit is observed at 3442 and 3100 cm−1. Another intense band is found at 1060 cm−1, which corresponds to the bending vibration absorption of the C–OH bonds. Figure 7b demonstrates the changes in covalent bonds when PDI is polymerized to the polymer PPDI. The appearance of peak corresponding to strong vibration absorption at 2310 cm−1 is attributed to the isocyanate groups (–N=C=O). Figure 7c displays the peak at 2300 cm−1, which is assigned to –N=C=O bond present in the PPDI layer on the surface of functionalized CF. It clearly demonstrates the existence of isocyanate groups on the surface of CF-PPDI hierarchical structure. Asymmetric stretching bands of the N–H bond are observed at 1510 cm−1, which confirm the occurrence of the reaction of isocyanate groups with hydroxyl groups to form N–H bond. The FTIR curve of the CF-PPDI-g-nanosilica is shown in Figure 7d, which exhibits the absorption peak at 1510 cm−1. The intensity of absorption peak is higher than that of CF-PPDI, thus confirming the continuous reaction of the isocyanate groups on the CF-PPDI


Page 16 of 37

Page 17 of 37

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


hierarchical structure with silanol groups to generate new N–H bonds. Two sharp stretching vibration absorption bands observed at 1104 and 820 cm−1 are ascribed to the characteristic group frequencies of Si–O–Si bond belonging to nanosilica. It demonstrates the successful grafting of nanosilica onto the surface of the CFs.

Figure 7. FTIR spectra of a) CF after acid treatment, b) PPDI, c) CF-PPDI-NCOx, and d) CF-PPDI-g-nanosilica.

The surface elemental compositions of the CF in different stages were detected by XPS and the scanning curves are depicted in Figure 8. The results of XPS indicate that the chemical element compositions of the acidified CF mainly consist of C, O, and a small amount of N (Figure 8a). The N and O are obtained due to the oxidation process by concentrated nitric acid. This process involves the appearance of several chemical bonds, including C–C, C–OH, C–O–C, and C=O–OH. Polymerization of the isocyanates on the surface of acidified CF led to the formation of the CF-PPDI, and its XPS curve is shown in Figure 8b. The content of N atom is obviously higher than that of acidified CF. The content of N atom and its source can be explicated in the following two ways: First is from isocyanates reacting with hydroxyl groups to form



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

the amido bonds. Second belongs to the C–N bond, formed during the self-polymerization of isocyanates. Figures. 8c and 8d show that grafting of nanosilica onto the CF leads to the appearance of the silicon (Si) on the surface of CF-PPDI-g-nanosilica hierarchical structure. The peak intensity of Si increases with the increase in the extent of nanosilica grafting. Thus, the results of both the XPS (Figure 8) and FTIR (Figure 7) also indicate the successful grafting of nanosilica onto the surface of the CFs.

Figure 8. The XPS curves of a) CF after acid treatment, b) CF-PPDI-NCOx, c) CF-PPDI-g-nanosilica (mCF : mnanosilica = 10:1), and d) CF-PPDI-g-nanosilica (mCF : mnanosilica = 5:1).

SEM was used to observe the surface morphologies of the CFs in different stages, including surface treatment and functionalization. Figure 9 shows the SEM images of the carbon precursor, CF refluxed with acetone, acid treated CF, CF-PPDI, and CF-PPDI-g-nanosilica hierarchical structure.


Page 18 of 37

Page 19 of 37

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 9. SEM images of a) CF precursor, b) CF refluxed with acetone, c) CF after acid treatment, d) CF-PPDI-NCOx, e) The broken topography of CF-PPDI-NCOx and f) CF-PPDI-g-nanosilica.

Surface topography of CF refluxed with acetone (Figure 9b) and acid treated CF (Figure 9c) is almost smooth; however, it exhibits the appearance of few weak grooves compared to the carbon precursor. Following the reaction with the isocyanates and self-polymerization, the CFs uniformly surround the PPDI polymer layer, as shown in Figure 9d and Figure 9e. The broken topography of CF-PPDI-NCOx could demonstrate the PPDI thin film coated on the surface of the CFs as an interfacial layer. Figure 9f exhibits the uniform distribution of nanosilica on the fiber surface, especially, the grafting ratio and graft density of nanosilica on the fiber surface could be altered by employing different reaction conditions. In addition, the PPDI polymer layer and silica particles on the surface of CFs has excellent chemical corrosion resistance in strong acid solution (Figure S1) and can slightly reduce the thermal conductivity of CFs (Figure S2).



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 20 of 37

The interfacial strength of the composites was evaluated by single fiber pull-out tests. The interfacial shear strength results of CF precursor, CF-PPDI-NCOx and silica nanoparticles grafted carbon fibers are shown in Figure 10. It can be obviously seen that the silica nanoparticles significantly increase the interfacial strength of the CF precursor. The IFSS increases from 16.6 MPa for the untreated CFs to 24.9 MPa for silica nanoparticles grafted carbon fibers by 50%. The BET surface areas of CF precursor, CF-PPDI-NCOx and silica nanoparticles grafted carbon fibers are also shown in Figure 10. The specific surface area was characterized by the BET method. The specific area of the CF precursor is calculated to be 0.24 m2/g. Both coating polymer layer and grafting silica nanoparticles on the surface of CFs can cause increased BET surface areas, the surface area of CF-PPDI-g-nanosilica is remarkable to

reach

10.28

m2/g.

It

should

be

noted

that

the

failure

region

of

CF-PPDI-g-nanosilica separated with epoxy resin has been characterized by SEM after IFSS test (Figure S3). There have hardly any silica nanoparticles on the CFs surface and most of the regions are relatively smooth, a few regions have the phenomenon of PPDI coating exfoliation from CFs, which show evidence of the fracture mainly happened on the interface between CF and PPDI-nanosilica, a few existed on the interface of CFs and PPDI coating.


Page 21 of 37

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 10. Interfacial shear strength and BET surface area of CF precursor, CF-PPDI-NCOx and CF-PPDI-g-nanosilica (From left to right).

In the research of carbon-fiber reinforced polymer composites, a weak interface between carbon fiber and polymer matrix may impair the integrity of composites and lead to the fibers pulling out from matrix, whereas a strong bond may induce brittle fracture behavior. Therefore, appropriate interface strength is beneficial to the performance of carbon fiber. The AFM images of CF precursor and CF-PPDI-g-nanosilica are shown in Figure 11. The surface topography and roughness between CF precursor and silica nanoparticles modified carbon fiber have remarkable differences. As shown in Figure 11a, the surface of untreated carbon fiber can be observed to be relatively smooth and have no bulge visibly, which is due to the untreated CFs surrounded by resin protective layer in manufacture process. After silica nanoparticles grafting onto the surface of CFs, the silica nanoparticles uniformly distribute on the surface of the fibers, it leads to the surface roughness of modified CFs increased from 2 nm to 19 nm. Thus, the addition of silica nanoparticles is beneficial to improve the surface roughness and provide more



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 22 of 37

interface contact points and the low interfacial layer thickness can guarantee the CFs surface surrounded completely by the coatings. In addition, an appropriate layer thickness would not have any negative effects on the mechanical properties of the fiber, on the contrary, the method can enhance the mechanical interlocking and interfacial adhesion between the fibers and the matrix.

Figure

11.

Representative

height

images

of

(a)

carbon

fiber

precursor

and

(b)

CF-PPDI-g-nanosilica.

SiBCN preceramic polymers were synthesized on the surface of three-dimensional carbon fiber architecture substrate, which HSiCl3, BCl3, and HMDZ were used as monomers. Then CF-PPDI-g-nanosilica/SiBCN preceramic polymers were converted to the CF-PPDI-g-nanosilica/SiBCN ceramic composites by pyrolysis at 1400 °C for 1 h. The precursor was ceramization in high temperature to amorphous SiBCN ceramics. Surface

morphologies

of

the

CF-PPDI-g-nanosilica/SiBCN

polymer

and

CF-PPDI-g-nanosilica/SiBCN ceramics are shown in Figure 12. Silica nanoparticles along CFs can be observed on the surface of the CFs substrate (Figure 9f). SiBCN preceramic polymers are uniformly coated onto the modified fiber surface (Figure 12a and b) after polymerization. These bulges on the CFs substrate, which caused by silica


Page 23 of 37

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


nanoparticles grown on the surface of CFs. After pyrolysis at 1400 °C, the preceramic polymers surround the CFs converted to amorphous ceramic and the SiBCN ceramic uniformly coated on the surface of CFs substrate (Figure 12c and d). Fig 12a and Fig 12d also reveal that the polymer and ceramic coating thickness can reach ca. 1.8 µm and 1.4 µm, respectively, it could coat the silica nanoparticles effectively and the SiBCN preceramic

would

have

a

significant

contraction

on

the

surface

of

CF-PPDI-g-nanosilica in the process of high temperature crosslinking. It was also beneficial to fix the silica nanoparticles on the surface of CFs tightly. Because CF-PPDI-g-nanosilica can be absolutely shielded by polymer and ceramic coating, the coating can prevent the contact of oxygen present in the air and effectively improve the antioxidant properties of the carbon-fiber reinforced polymer composite materials.

Figure 12. SEM images of a) and b) CF-PPDI-g-nanosilica/SiBCN polymer, c) and d) CF-PPDI-g-nanosilica/SiBCN ceramics.

The

FTIR

spectrum

of


polymer

and

CF-PPDI-g-nanosilica/SiBCN ceramics shown in Figure 13 indicates the changes of



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

various covalent bonds. Figure 13a shows that the absorption peak corresponding to the stretching vibration at 3159 and 2232 cm−1, which are due to N–H, and Si–H. A strong and broad vibration band overlapping with B–N and C–H group appears at 1407 cm−1. The peaks at 2960 and 2810 cm−1 appear separately, which attribute to the formation of C–H bond and Si–C bond. The C–H and Si–C bond stretching absorptions overlap at 1268 cm−1. Si–N group attached to boron atom appears at 835 cm−1, a sharp peak. All signals of chemical bonds indicate the CFs substrate coated by SiBCN preceramic polymer completely. When the CF-PPDI-g-nanosilica/SiBCN polymer was pyrolysis at 1400 °C, the polymer coating converted to SiBCN ceramic. Figure 13b clearly exhibits the formation of new chemical bonds. A strong stretching vibration absorption peak corresponding to B-N appears at 1411 cm-1. Another sharp stretching vibration absorption peak is observed at 1075 cm-1, which is attributed to Si-N bond. The peaks at 890 and 782 cm−1 appear separately, which be assigned to the formation of Si–C bond. The results demonstrate the SiBCN precursor surround the CFs converted to amorphous SiBCN ceramic and uniformly coated on the surface of CFs substrate. The elemental compositions of the surface of the modified CFs with SiBCN polymer and ceramic coating were investigated by XPS, and the scanning curves are exhibited in Figure 13c and Figure 13d. The chemical elemental compositions of the CF-PPDI-g-nanosilica/SiBCN polymer are basically composed of Si, B, C and N, which are assigned to SiBCN precursor. The chemical bonds mainly consist of Si-C, Si-N and B-N. Figure 13c clearly display that a strong peak at around 101.8 eV


Page 24 of 37

Page 25 of 37

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


assigned to Si-C and Si-N bond, the weak signal peak at 190.6 eV is attributed to the B-N bond. Another strong peak at 248.8 eV ascribed to sp2-hybridized carbon. The existence of peak at 401.3 eV confirms the presence of N-containing bond (N-B and N-Si) on the surface of modified CFs substrate. After pyrolysis at 1400 °C, the element contents (B and N) of CF-PPDI-g-nanosilica/SiBCN ceramics (Figure 13d) dramatically decline that indicate that the precursor has successfully converted to amorphous ceramics.

Figure

13.

FTIR

spectra

of



polymer

(a)

and


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

CF-PPDI-g-nanosilica/SiBCN ceramics (b); XPS curves of CF-PPDI-g-nanosilica/SiBCN polymer (c) and CF-PPDI-g-nanosilica/SiBCN ceramics (d).

The thermal gravimetric analysis technique in a flowing air atmosphere was used to investigate the dynamic oxidation behavior of CF-PPDI-g-nanosilica, SiBCN precursor, SiBCN ceramic and CF-PPDI-g-nanosilica/SiBCN ceramic, simultaneously the CFs substrate was used as reference substance. The TG curves of the CFs can be observed in Figure 14a. The untreated CFs precursor has a little weight loss during their initial heating from 28 to 300 °C, and the weight remains ca. 98 %. Then the CFs substrate emerges a significant drop off in mass from 579 to 799 °C, CFs substrate is oxidized completely at this moment. The reason of remarkable weight loss can be ascribed to the oxidation of CFs resulting in the formation of carbon monoxide (CO) and carbon dioxide (CO2) during the heating-up process. As shown in Figure 14b, the CF-PPDI-g-nanosilica has a stable curve from 28 to 254 °C, then the sample weight begins to decrease until 560 °C, the weight reduces to 93.6%, which can be ascribe to the PPDI layer decomposition in high temperature. Then CF-PPDI-g-nanosilica weight proportion has a dramatic decline from 93.6% to 0%. The sample is oxidized completely until the temperature up to 896 °C, it is owing to the surface of CFs substrate grafted by a large number of silica nanoparticles. SiBCN preceramic and SiBCN ceramic weight loss curves can be seen in Figure 14c and Figure 14d. The results show that the residual mass of two samples retain at 75 % and 90 % until 1200 °C under air atmosphere, respectively. That indicates the pure SiBCN ceramic has a good thermal stability in air atmosphere. SiBCN precercamic need to convert to noncrystalline SiBCN ceramic from organic precursor, so the sample has more weight


Page 26 of 37

Page 27 of 37

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


loss [26]. When the CF-PPDI-g-nanosilica with SiBCN ceramic coating is heating-up to 1200 °C, the residual mass reaches to 84 %, this process can be divided into two parts: Firstly, the CF-g-GO/SiBCN ceramic decreases slowly from 28 to 886 °C; Secondly, the weigh begins to rise slightly until constant weight. The weight loss of CF-PPDI-g-nanosilica with SiBCN ceramic can be ascribed to the boron nitride oxidation in SiBCN ceramic layer, and then the SiBCN ceramic could convert to silica and boron oxide in higher temperature, the oxidation products represent a glassy structure, which can seal the surface defects to protect the CFs substrate from the oxidization in aerobic environment effectively. Therefore, the interface modification method has a good potential application in the preparation of functional nanocomposite materials.

Figure 14. TG curves of (a) CF precursor, (b) CF-PPDI-g-nanosilica, (c) SiBCN precursor, (d) SiBCN ceramic and (e) CF-PPDI-g-nanosilica/SiBCN ceramic at a heating rate of 10 °C min−1 in air from 25 to 1200 °C.

4. Conclusions



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 28 of 37

In this study, PPDI polymer and silica nanoparticles functionalized CFs were facilely prepared by in-situ polymerization and chemical grafting methods. PPDI polymer layer was formed on the surface of the CFs by addition polymerization. PPDI itself contained numerous unreactive isocyanate groups, which could be used as macromolecule coupling agent to react efficiently with silica nanoparticles in a continual process. The CFs were functionalized by the combination of nanosilica with isocyanates through the reaction between isocyanate groups on the PPDI polymer and silanol groups of nanosilica. The CF-PPDI-g-nanosilica hierarchical structure improved the interfacial adhesion between the fibers and nanosilica, and enhanced the mechanical properties of the CFs. Specifically, compared to the CFs precursor, the interfacial shear strength of functionalized CFs was dramatically increased by 50%. Compared to the method reported in the literature, the method employed in this study involved an easy, simple, and convenient preparation of silica nanoparticles coating on the CFs. Thus, this method is significantly beneficial to fabricate CF reinforced polymer composites by providing high surface roughness

and

mechanical

interlocking. Furthermore, siliconborocarbonitride (SiBCN) ceramic was used as protective layer to enhance carbon fibers substrate antioxidant and ablation properties. Thermogravimetric results show that silica nanoparticles functionalized CFs with SiBCN ceramic layer exhibited an excellent antioxidant performance under high temperature environment.

Corresponding Author *E-mail: [email protected]; [email protected]; [email protected]


Page 29 of 37

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Notes The authors declare no competing financial interest.

Acknowledgments: This work was supported by research grants from the National Nature Science Foundation of China (NO. 11572105) and National Outstanding Youth Foundation of China (NO. 51525201).

References (1) Drzal, L. T.; Madhukar, M. Fibre-matrix adhesion and its relationship to composite mechanical properties. J. Mater. Sci. 1993, 28, 569–610. (2) Hughes, J. D. The carbon fibre/epoxy interface-a review. Compos. Sci. Technol. 1991, 41, 13–45. (3) Hyer, M. W. Stress Analysis of Fiber Reinforced Composite Materials. Boston, MA: McGraw-Hill. 1998, 28–30. (4) Mei, H., Cheng, L. F. Comparison of the mechanical hysteresis of carbon/ceramic matrix composites with different fiber preforms. Carbon 2009, 47, 1034–1042. (5) Li, H. J., Yao, D. J., Fu, Q. G., Liu, L., Zhang, Y. L., Yao, X. Y., Wang, Y. J., Li, H. L. Anti-oxidation and ablation properties of carbon/carbon composites infiltrated by hafnium boride. Carbon 2013, 52, 418-426. (6) Zhou, G. H., Liu, Y. Q., He, L. L., Guo, Q. G., Ye, H. Q. Microstructure difference between core and skin of T700 carbon fibers in heat-treated carbon/carbon composites. Carbon 2011, 49, 2883-2892. (7) Tang, L. G., Kardos, J. L., Hoffman, W. P. A review of methods for improving the



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

interfacial adhesion between carbon fiber and polymer matrix. Polym. Compos. 2004, 18, 100–113. (8) Liu, H. M., Wang, X., Fang, P. F., Wang, S. J., Qi, X., Pan, C. X., Xie, G. Y., Liew, K. M. Functionalization of multi-walled carbon nanotubes grafted with self-generated functional groups and their polyamide 6 composites. Carbon 2010, 48, 721–729. (9) Rodriguez, A. J., Guzman, M. E., Lim, C. S., Minaie, B. Mechanical properties of carbon nanofiber/fiber-reinforced hierarchical polymer composites manufactured with multiscale reinforcement fabrics. Carbon 2011, 49, 937–948. (10) Pingkarawat, K., Bhat, T., Craze, D. A., Wang, C. H., Varleyb, R. J., Mouritz, A. P. Healing of carbon fibre–epoxy composites using thermoplastic additives. Polym. Chem. 2013, 4, 5007-5015. (11) Steiner, S. A., Li, R., Wardle, B. L. Circumventing the mechanochemical origins of strength loss in the synthesis of hierarchical carbon fibers. ACS Appl. Mater. Interfaces 2013, 5, 4892–4903. (12) Liu, Y., Kumar, S. Recent progress in fabrication, structure, and properties of carbon fibers. Polym. Rev. 2012, 52, 234–258. (13) Zhang, G., Sun, S., Yang, D., Dodelet, J. P., Sacher, E. The surface analytical characterization of carbon fibers functionalized by H2SO4/HNO3 treatment. Carbon 2008, 46, 196–205. (14) Chen, J., Wei, G., Maekawa, Y., Yoshida, M., Tsubokawa, N. Grafting of poly(ethylene- block-ethylene oxide) onto a vapor grown carbon fiber surface by γ-ray radiation grafting. Polymer 2003, 44, 3201–3207.


Page 30 of 37

Page 31 of 37

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(15) Keller, T. M. Oxidative protection of carbon fibers with poly(carborane– siloxane–acetylene). Carbon 2011, 40, 225-229. (16) Shioya, M., Inoue, H., Sugimoto, Y. Reduction in tensile strength of polyacrylonitrile-based carbon fibers in liquids and its application to defect analysis. Carbon 2013, 65, 63-70. (17) Zhu, C., Liu, X., Yu, X., Zhao, N., Liu, J., Xu, J. A small-angle X-ray scattering study and molecular dynamics simulation of microvoid evolution during the tensile deformation of carbon fibers. Carbon 2012, 50, 235–243. (18) Naito, K., Tanaka, Y., Yang, J. M., Kagawa, Y. Tensile properties of ultrahigh strength PAN-based, ultrahigh modulus pitchbased and high ductility pitch-based carbon fibers. Carbon 2008, 46, 189–195. (19) Loidl, D., Paris, O., Burghammer, M., Riekel, C., Peterlik, H. Direct observation of nanocrystallite buckling in carbon fibers under bending load. Phys. Rev. Lett. 2005, 95, 225501. (20) Qin, X., Lu, Y., Xiao, H., Wen, Y., Yu, T. A comparison of the effect of graphitization on microstructures and properties of polyacrylonitrile and mesophase pitch-based carbon fibers. Carbon 2012, 50, 4459–4469. (21) Ozbek, S., Isaac, D. H. Strain-induced density changes in PAN based carbon fibres. Carbon 2000, 38, 2007–2016. (22) Gao, L., Thostenson, E. T., Zhang, Z., Chou, T. W. Sensing of damage mechanisms in fiber-reinforced composites under cyclic loading using carbon nanotubes. Adv. Funct. Mater. 2009, 19, 123–130.



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

(23) Liu, Y. Q., He, L. L., Lu, X. F., Xiao, P. Transmission electron microscopy study of the microstructure of carbon/carbon composites reinforced with in situ grown carbon nanofibers. Carbon 2012, 50, 2424–2430. (24) Qian, H., Bismarck, A., Greenhalgh, E. S., Kalinka, G., Shaffer, M. S. P. Hierarchical composites reinforced with carbon nanotube grafted fibers: the potential assessed at the single fiber level. Chem. Mater. 2008, 20, 1862–1869. (25) Dzenis, Y. Structural nanocomposites. Science 2008, 319, 419–420. (26) Han, W. B., Zhao, G. D., Zhang, X. H., Zhou, S. B., Wang, P., An, Y. M., Xu, B. S.

In

situ

polymerized

graphene oxide grafted carbon fiber reinforced

siliconboro-carbonitride ceramics with enhanced thermal stability. Carbon 2015, 95, 157–165. (27) Veedu, V. P., Cao, A. Y., Li, X. S, Ma, K. G., Soldano, C., Kar, S., Ajayan, P. M., Ghasemi-Nejhad, M. N. Multifunctional composites using reinforced laminae with carbon-nanotube forests. Nat. Mater. 2006, 5, 457–462. (28) Peng, H., Alemany, L. B., Margrave, J. L., Khabashesku, V. N. Sidewall carboxylic acid functionalization of single-walled carbon nanotubes. J. Am. Chem. Soc. 2003, 125, 15174–15182. (29) Banerjee, S., Hemraj, B. T., Wong, S. S. Covalent surface chemistry of single walled carbon nanotubes. Adv. Mater. 2005, 17, 17–29. (30) Qian, H., Greenhalgh, E. S., Shaffer, M. S. P., Bismarck, A. Carbon nanotube-based hierarchical composites: a review. J. Mater. Chem. 2010, 20, 4751– 4762.


Page 32 of 37

Page 33 of 37

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(31) Yu, M. F., Files, B. S., Arepalli, S., Ruoff, R. S. Tensile loading of ropes of single wall carbon nanotubes and their mechanical properties. Phys. Rev. Lett. 2000, 84, 5552–5555. (32) Li, Y. B., Peng, Q. Y., He, X. D., Hu, P. A., Wang, C., Shang, Y. Y., Wang, R, G., Jiao, W. C., Lv, H. Z. Synthesis and characterization of a new hierarchical reinforcement by chemically grafting graphene oxide onto carbon fibers. J. Mater. Chem. 2012, 22, 18748-18752. (33) Lu, X. F., Xiao, P. Preparation of in situ grown silicon carbide nanofibers radially onto carbon fibers and their effects on the microstructure and flexural properties of carbon/carbon composites. Carbon 2013, 59, 176-183. (34) Song, Q., Li, K. Z., Li, H. L., Li, H. J., Ren, C. Grafting straight carbon nanotube radially onto carbon fibers and their effect on the mechanical properties of carbon/carbon composites. Carbon 2012, 50, 3943–3960. (35) Gong, Q. M., Li, Z., Zhou, X. W., Wu, J. J., Wang, Y., Liang, J. Synthesis and characterization of in situ grown carbon nanofiber/nanotube reinforced carbon/carbon composites. Carbon 2005, 43, 2426–2429. (36) Du, X. S., Liu, H. Y., Zhou, C. F., Moody, S., Mai, Y. W. On the flame synthesis of carbon nanotubes grafted onto carbon fibers and the bonding force between them. Carbon 2012, 50, 2347–2350. (37) Kim, K. J., Kim, J., Yu, W. R., Youk, J. H., Lee, J. Improved tensile strength of carbon fibers undergoing catalytic growth of carbon nanotubes on their surface. Carbon 2013, 54, 258–267.



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

(38) Kim, K. J., Yu, W. R., Youk, J. H., Lee, J. Degradation and healing mechanisms of carbon fibers during the catalytic growth of carbon nanotubes on their surfaces. ACS Appl. Mater. Interfaces 2012, 4, 2250–2258. (39) Agnihotri, P., Basu, S., Kar, K. K. Effect of carbon nanotube length and density on the properties of carbon nanotube-coated carbon fiber/polyester composites. Carbon 2011, 49, 3098–3106. (40) Zhao, J. G., Liu, L., Guo, Q. G., Shi, J. L., Zhai, G. T., Song, J. R., Liu, Z. J. Growth of carbon nanotubes on the surface of carbon fibers. Carbon 2008, 46, 380– 383. (41) Zhao, F., Huang, Y. D. Preparation and properties of polyhedral oligomeric silsesquioxane and carbon nanotube grafted carbon fiber hierarchical reinforcing structure. J. Mater. Chem. 2011, 21, 2867-2870. (42) Godaraa, A., Mezzoa, L., Luizia, F., Warrierb, A., Lomovb, S. V., Vuureb, A. W. Influence of carbon nanotube reinforcement on the processing and the mechanical behaviour of carbon fiber/epoxy composites. Carbon 2009, 47, 2914-2923. (43) Peng, Q. Y., He, X. D., Li, Y. B., Wang, C., Wang, R. G., Hu, P. A., Yan, Y. D., Sritharan, T. Chemically and uniformly grafting carbon nanotubes onto carbon fibers by poly(amidoamine) for enhancing interfacial strength in carbon fiber composites. J. Mater. Chem. 2012, 22, 5928–5931. (44) Balazs, A. C.; Emrick, T.; Russell, T. P. Nanoparticle Polymer Composites: Where Two Small Worlds Meet. Science 2006, 314, 1107-1110. (45) Krishnamoorti, R.; Vaia, R. A. J. Polymer Nanocomposites. J. Polym. Sci., Part


Page 34 of 37

Page 35 of 37

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


B: Polym. Phys. 2007, 45, 3252-3256. (46) Zhao, G. D., Zhang, P. P., Zhang C. B., Zhao, Y. L. Facile synthesis of highly pure block copolymers by combination of RAFT polymerization, click reaction and de-grafting process. Polym. Chem. 2012, 3, 1803-1812. (47) Hajji, P.; David, L.; Gerard, J. F.; Pascault, J. P.; Vigier, G. Synthesis, structure, and morphology of polymer–silica hybrid nanocomposites based on hydroxyethyl methacrylate. J. Polym. Sci., Part B: Polym. Phys. 1999, 37, 3172-3187. (48) Althues, H.; Henle, J.; Kaskel, S. Functional inorganic nanofillers for transparent polymers. Chem. Soc. Rev. 2007, 36, 1454-1465. (49) Zou, H., Wu, S. S., Shen, J. Polymer/Silica Nanocomposites: Preparation, Characterization, Properties, and Applications. Chem. Rev. 2008, 108, 3893–3957 (50)

Schottner,

G.

Hybrid

Sol−Gel-Derived

Polymers:

Applications

of

Multifunctional Materials. Chem. Mater. 2001, 13, 3422-3435. (51) Caruso, R. A.; Antonietti, M. Sol−Gel Nanocoating: An Approach to the Preparation of Structured Materials. Chem. Mater. 2001, 13, 3272-3282. (52) Merkel, T. C.; Freeman, B. D.; Spontak, R. J.; He, Z.; Pinnau, I.; Meakin, P.; Hill, A. J. Ultrapermeable, reverse-selective nanocomposite membranes. Science 2002, 296, 519-522. (53) Merkel, T. C.; Freeman, B. D.; Spontak, R. J.; He, Z.; Pinnau, I.; Meakin, P.; Hill, A. J. Sorption, Transport, and Structural Evidence for Enhanced Free Volume in Poly(4-methyl-2-pentyne)/Fumed Silica Nanocomposite Membranes. Chem. Mater.



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

2002, 15, 109-123. (54) Ionescu, E., Kleebeb, H. J., Riedela, R. Silicon-containing polymer-derived ceramic nanocomposites (PDC-NCs): preparative approaches and properties. Chem. Soc. Rev. 2012, 41, 5032-5052. (55) Riedel, R., Kienzle, A., Dressler, W., Ruwisch, L., Bill, J., Aldinger, F., A Silicoboron Carbonitride Ceramic Stable to 2000 oC. Nature 1996, 382, 796-798. (56) Su, K., Remsen, E. E., Zank, G. A., Sneddon, L. G. Synthesis, Characterization, and Ceramic Conversion Reactions of Borazine-Modified Hydridopolysilazanes: New Polymeric Precursors to Silicon Nitride Carbide Boride (SiNCB) Ceramic Composites. Chem. Mater. 1993, 5, 547-556. (57) Weinmann, M., Schuhmacher, J., Kummer, H., Prinz, S., Peng, J., Seifert, H. J., Christ, M., Muller, K., Bill, J., Aldinger, F. Synthesis and Thermal Behavior of Novel Si–B–C–N Ceramic Precursors. Chem. Mater. 2000, 12, 623-632. (58) Jaschke, T., Jansen, M. A new borazine-type single source precursor for Si/B/N/C ceramics. J. Mater. Chem. 2006, 16, 2792-2799. (59) Bernard S, Weinmann M, Gerstel P, Miele P, Aldinger F. Boron-modified polysilazane as a novel single-source precursor for SiBCN ceramic fibers: synthesis, melt-spinning, curing and ceramic conversion. J. Mater. Chem. 2005, 15, 289-299. (60) Lee, J. S., Butt, D. P., Baney, R. H., Bowers, C. R., Tulenko, J. S. Synthesis and pyrolysis of novel polysilazane to SiBCN ceramic. J. Non-Cryst. Solids 2005, 351, 2995-3005.


Page 36 of 37

Page 37 of 37

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


TOC graphic


Ordered Silica Nanoparticles Grown on a Three-Dimensional Carbon

Recommend Documents