- Email: [email protected]
Processing of in situ synthesized polycarbosilane-derived porous SiC using kraft pulp fibers
Accepted Manuscript Processing of in-situ synthesized polycarbosilane-derived porous SiC using Kraft pulp fibers Hatim Laadoua, Romain Lucas, Yves Champavier, Sylvie Foucaud, Rachida Zerrouki, François Brouillette PII: DOI: Reference:
S0167-577X(17)30005-8 http://dx.doi.org/10.1016/j.matlet.2017.01.004 MLBLUE 21957
To appear in:
Materials Letters
Received Date: Revised Date: Accepted Date:
13 November 2016 20 December 2016 2 January 2017
Please cite this article as: H. Laadoua, R. Lucas, Y. Champavier, S. Foucaud, R. Zerrouki, F. Brouillette, Processing of in-situ synthesized polycarbosilane-derived porous SiC using Kraft pulp fibers, Materials Letters (2017), doi: http://dx.doi.org/10.1016/j.matlet.2017.01.004
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Processing of in-situ synthesized polycarbosilane-derived porous SiC using Kraft pulp fibers Hatim Laadoua,a Romain Lucas,a* Yves Champavier,b Sylvie Foucaud,a Rachida Zerrouki,c,d François Brouilletted a
b
Université de Limoges, SPCTS, UMR 7315, F-87068, Limoges, France
Service Commun de Recherche et d’Analyse de Biomolécules de Limoges, F-87025, Limoges, France c
d
Université de Limoges, LCSN, UPRES EA1069, F-87060, Limoges, France
Centre de recherche sur les matériaux lignocellulosiques (CRML), Université du
Québec à Trois-Rivières, 3351 boul. des Forges C.P. 500, Trois-Rivières, Canada
Corresponding author: Dr. R. Lucas, SPCTS-CNRS, UMR 7315 Centre Européen de la Céramique 12 Rue Atlantis, F-87068 Limoges Cedex, France Tel: (+)33587502350 Fax: (+)33587502304 E-mail: [email protected]
Abstract: SiC ceramics were fabricated using the polymer derived ceramics route with Kraft pulp fibers (KPF) and organosilicon monomers as starting materials. For this, KPF or Propargylated Kraft pulp fibers (PKPF) were used as natural templates to be impregnated with a polycarbosilane
(PCS),
synthesized
in
situ
thanks
to
a
hydrosilylation
reaction.
Characterizations of the pyrolyzed materials were carried out at different stages by means of TGA coupled with mass spectrometry, XRD and SEM. Depending on the initial template, either KPF or PKPF, SiC ceramics were generated with a porous network and fiber structures, respectively. Keywords: Polymer-derived ceramics; Kraft pulp fibers; SiC
1
1. Introduction Silicon carbide is a non-oxide ceramic with attractive physicochemical and structural properties for a wide range of industrial applications. Depending on the architecture of the developed SiC, the applications can be varied. Indeed, porous SiC can be used as catalyst supports [1] or separation membranes [2], while SiC fibers are utilized for reinforcement of composites [3]. There are several techniques to produce a designed SiC [4-6]. In recent years, biotemplating is increasingly recommended to produce ceramic composite materials using natural templates like wood, organic fibers, cellulose fibers, etc. [7,8]. The cellular architecture of native wood materials, such as lignocellulosic fibers, was optimized through biomimetic microstructures, which are much more complex and difficult to produce artificially. However, these methods require a two-step high-temperature treatment to obtain the SiC ceramic material [9]. In this study, only one heat treatment was performed in order to obtain an organized SiC. For that, Kraft pulp fibers (KPF) and O-propargylated Kraft pulp fibers (PKPF), Figure 1a) are used as a sacrificial template to be impregnated with a preceramic hyperbranched polycarbosilane (PCS), synthesized in situ thanks to a hydrosilylation reaction. The alkyne functionalization was chosen to evaluate the possible reaction between PKPF and the polymer under construction, and to observe the impact on the final ceramic structure. Additionally, the thermal behavior of the fibers as well as the composite systems was investigated.
2. Experimental 2.1. Fabrication of the composite system For the preparation of the composite system, tetraallylsilane (TAS) (C12H20Si, 97% purity), and 1,4-bis(dimethylsilyl)benzene (BDSB) (C6H4[SiH(CH3)2]2, 97% purity) were used to synthesize a hyperbranched polymer via a hydrosilylation reaction (Figure 1b) in the presence of KPF or PKPF. For this, 30 mg of KPF (bleached softwood kraft pulp supplied by Kruger Wayagamack, Trois-Rivières Canada) and PKPF (see Supporting Information) were placed separately in two beakers, each containing 4 mL of toluene (99.5% purity). They were then subjected to an ultrasound bath for 15 minutes to promote the dispersion of fibers. Then, 491 µL of TAS (2.12 mmol) and 959 µL of BDSB (4.3 mmol) were added to each mixture, in a 20 mm diameter mold (i.e. 95.7 vol% of ceramic precursors and 4.3 vol% of fibers). Finally, 70 µL of a solution containing 450 µL of toluene and 50 µL of Karstedt catalyst (0.11 mmol) were added dropwise to catalyze the hydrosilylation reaction. After 24 hours, a gel formation was observed, surrounding the fibers. This led to samples with an average thickness of 1.7 mm. The propargylation of KPF is described in supporting information.
2
Fig. 1. Functionalization of KPF (a) and the hydrosilylation reaction leading to the PCS (b)
2.2. Characterizations 2.2.1. Fibers The propargylation was highlighted based on the FT-IR results of Pierre Antoine Faugeras et al. [10]. The thermal behavior of KPF and PKPF was investigated using a thermogravimetric -1
−1
analyzer (STA 449F3-Netzsch 1400 °C, argon flow: 20 mL.min , Heating rate (v): 10 °C.min ) coupled with a Mass Spectrometer (Omnistar, Balzers Instrument).
2.2.2. Composite system Phase identification was carried out by X-ray diffraction on powders (Bruker D8, Germany) using the CuKα radiation. The microstructures of the specimens before and after heat treatment were observed using Scanning Electron Microscopy (XL 30Philips TM, Eindhoven, Netherlands). The thermal behavior of the composites (KPF + PCS = C1) and (PKPF + PCS = C2) were investigated using a thermogravimetric analyzer (STA 449F3-Netzsch 1400 °C, argon -1
flow: 20 mL.min ) with a heating rate of 5 °C.min 10 °C.min
−1
−1
to 300 °C (2 h temperature hold) and then
to 1400 °C (1 h temperature hold). This TGA was also coupled with a Mass
Spectrometer (Omnistar, Balzers Instrument) to determine the species released during heating.
3. Results and discussion 3.1. Thermal behavior of fibers The thermal behavior of the fibers was studied (Figure 2). DSC analyses revealed that the two types of fibers have a similar behavior, so only the KPF DSC curve is presented. It is observed that all the fibers are consumed after heating up to 1400 °C and three domains are detected. Between 30 and 260 °C (domain I), a low weight loss of 8% is accompanied by a fairly exothermic event at 106 °C which coincides with water boiling temperature. Indeed, the MS highlights ionized fragments at m/z = 18 (H2O) resulting from dehydration of the cellulose [11]. Between 260 and 380 °C (domain II), a significant weight loss of 76% is observed, with an intense endothermic phenomenon at 346 °C. In this domain, various MS volatile fragments are
3
+
+
detected at m/z = 17 (OH ); 18 (H2O); 29 (C2H5 ) and 44 (CO2) [11]. In these 2 domains, KPF and PKPF show similar TGA-DSC and MS results. Nevertheless, a difference appears in the temperature range between 400 and 800 °C (domain III). Indeed, KPF tend to be degraded sooner than PKPF. MS analyses of the two fibers detect volatile products at m/z = 44 (CO2) as +
well as ionized fragments at m/z = 43 (C2H3O ). In the temperature range between 400 and 800 °C, the propargylation definitely delays the thermal degradation of PKPF.
Fig. 2. TGA-DSC of KPF and PKPF treated at 1400 °C (top), and TGA-DSC-MS of the composites (bottom)
4
3.2. Thermal behaviors of the composite systems The composite systems were analyzed by TGA-DSC-MS following the same thermal cycle considered for the pyrolysis (Figure 2). DSC analyses revealed that the two types of composite behave similarly, so only the DSC curve of the composite with PKPF was presented. The ceramic yield of the composite with PKPF is somewhat higher (24%) than the one with KPF (20%). The TGA shows 4 domains of weight loss for both systems. Domain I’ presents a weight loss of 10% for C2 and 6% for C1. These last are accompanied by an exothermic event at 52.5 min (294 °C). MS analyses highlight volatile fragments at m/z = 44 (CO2) for the two types of +
composite. In addition to CO2, the ionized fragment at m/z = 42 (C3H6 ) was detected in the case of C2 which explains its greater weight loss. In domain (II’), no weight loss was observed. This corresponds to the structuration of the material. Domain (III’) shows a weight loss of 59% for C2 and 68% for C1. These weight losses are accompanied by a strong exothermic event at +
+
182.5 min (385 °C). The MS detects ionized fragments at m/z = 15 (CH3 ); 26 (C2H2 ); 41 +
+
+
+
(C3H5 ); 42 (C3H6 ); 73 (Si-C3H9 ); 43 (C2H3O ) and CO2 at m/z = 44. These signals are the results of the fragmentation of both the fibers and the polycarbosilane and they are detectable in the two composites. In domain (IV’) a small weight loss of 7% for C2 and 5% for C1 are noticed, related to the CO2 and CH3 releases. The composites were pyrolyzed following the same heating cycle as TGA. XRD analyses, of the two composites emphasize the presence of β-SiC slightly crystallized or nano-crystallized (see Supporting Information). A broad signal at low angles was detected, and may be due to the residual amorphous carbon phase in the specimens.
3.3. Morphologies of the composites Before pyrolysis (Figure 3), considering PKPF, the PCS is formed on the surface of the fibers or it coats the entire fiber and matches its shape. In parallel, (Figure 3a) shows that the KPF are trapped within the polymer matrix. To explain this difference of behavior, an analysis by FT-IR spectroscopy was performed, but it did not allow us to clearly testify the reaction between the alkyne function of PKPF and the Si-H bond of the BDSB. After pyrolysis, C1 displays both dense and porous areas. These present a non-homogenous pore size distribution (from 20 to 60 µm for small pores, and from 80 to 200 µm for the large ones), which may be due to the removal of fibers during the ceramization of the PCS. For C2, both dense areas and fibrous SiC areas are observed. It may arise from the ceramization of the PCS which impregnated the fibers and imitated its shape, and led to a replica of the original fiber-based template.
5
Fig. 3. SEM images of C1 (a) and C2 (b) before pyrolysis, C1 (c) and C2 (d) after pryrolysis
4. Conclusion In this study, KPF and PKPF were used as a natural template to be impregnated by a PCS synthesized in-situ thanks to a hydrosilylation reaction. The composite systems were characterized by TGA-DSC-MS and SEM to evaluate their thermal behavior and morphology. Depending on the initial template, either KPF or PKPF, a composite was obtained, with a porous network or fiber structures of SiC, respectively. These results highlight the likely binding between the polymer and the alkyne functions for C2, and would allow for the future development of controlled designed materials, from defined natural templates. These latter could be used either as catalyst supports (porous structure), or as fibers reinforcement of composites (fiber structure).
References [1] M. J. Ledoux, C. Pham-Huu, Silicon Carbide: A Novel Catalyst Support for Heterogeneous Catalysis, CATTECH 5 (2001) 226-246. [2] M. Fukushima, Y.Zhou, H. Miyazaki, Y. Yoshizawa, K. Hirao, Microstructural Characterization of Porous Silicon Carbide Membrane Support With and Without Alumina Additive , J. Am. Ceram. Soc. 89 (2006) 1523-1529. [3] Y. Gou, H. Wang, K. Jian, C. Shao, X. Wang, Preparation and characterization of SiC fibers with diverse electrical resistivity through pyrolysis under reactive atmospheres, J. Eur. Ceram. Soc. 37 (2017) 517-522. [4] J.H. Eom, Y.W. Kim, S. Raju, Processing and properties of macroporous silicon carbide ceramics: A review, J. Asian Ceram. Soc. 1 (2013) 220-242.
6
[5] Y.W. Kim, J.H. Eom, C. Wang, C.B. Park, Processing of Porous Silicon Carbide Ceramics from Carbon-Filled Polysiloxane by Extrusion and Carbothermal Reduction, J. Am. Ceram. Soc. 91 (2008) 1361-1364. [6] Y.J. Jin, Y.W. Kim, Low Temperature Processing of Highly Porous Silicon Carbide Ceramics with Improved Flexural Strength, J. Mater. Sci. 45 (2010) 282-285. [7] P. Greil, Biomorphous ceramics from lignocellulosics, J. Eur. Ceram. Soc. 21 (2001) 105118. [8] A.R. Maddocks, A.T. Harris, Biotemplated synthesis of novel porous SiC, Mater. Lett. 63 (2009) 748-750. [9] H. Sieber, C. Hoffmann, A. Kaindl, P. Greil, Biomorphic Cellular Ceramics , Adv. Eng. Mater. 2 (2000) 105-109. [10] P.A. Faugeras, P.H. Elchinger, F. Brouillette, D. Montplaisir, R. Zerrouki, Advances in cellulose chemistry - microwave-assisted synthesis of propargylcellulose in aqueous medium, Green Chem.14 (2012) 598-600. [11] D. López-González, M. Fernandez-Lopez, J.L. Valverde, L. Sanchez-Silva, Thermogravimetric-mass spectrometric analysis on combustion of lignocellulosic biomass, Bioresour.Technol. 143 (2013) 562-574.
7
8
An easy polymerization of carbosilanes was carried out with KPF via hydrosilylation Porous or fibrous SiC were obtained from natural templates and preceramic polymers The fiber functionalization directly impacts the final microstructure of the composites
9
S0167-577X(17)30005-8 http://dx.doi.org/10.1016/j.matlet.2017.01.004 MLBLUE 21957
To appear in:
Materials Letters
Received Date: Revised Date: Accepted Date:
13 November 2016 20 December 2016 2 January 2017
Please cite this article as: H. Laadoua, R. Lucas, Y. Champavier, S. Foucaud, R. Zerrouki, F. Brouillette, Processing of in-situ synthesized polycarbosilane-derived porous SiC using Kraft pulp fibers, Materials Letters (2017), doi: http://dx.doi.org/10.1016/j.matlet.2017.01.004
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Processing of in-situ synthesized polycarbosilane-derived porous SiC using Kraft pulp fibers Hatim Laadoua,a Romain Lucas,a* Yves Champavier,b Sylvie Foucaud,a Rachida Zerrouki,c,d François Brouilletted a
b
Université de Limoges, SPCTS, UMR 7315, F-87068, Limoges, France
Service Commun de Recherche et d’Analyse de Biomolécules de Limoges, F-87025, Limoges, France c
d
Université de Limoges, LCSN, UPRES EA1069, F-87060, Limoges, France
Centre de recherche sur les matériaux lignocellulosiques (CRML), Université du
Québec à Trois-Rivières, 3351 boul. des Forges C.P. 500, Trois-Rivières, Canada
Corresponding author: Dr. R. Lucas, SPCTS-CNRS, UMR 7315 Centre Européen de la Céramique 12 Rue Atlantis, F-87068 Limoges Cedex, France Tel: (+)33587502350 Fax: (+)33587502304 E-mail: [email protected]
Abstract: SiC ceramics were fabricated using the polymer derived ceramics route with Kraft pulp fibers (KPF) and organosilicon monomers as starting materials. For this, KPF or Propargylated Kraft pulp fibers (PKPF) were used as natural templates to be impregnated with a polycarbosilane
(PCS),
synthesized
in
situ
thanks
to
a
hydrosilylation
reaction.
Characterizations of the pyrolyzed materials were carried out at different stages by means of TGA coupled with mass spectrometry, XRD and SEM. Depending on the initial template, either KPF or PKPF, SiC ceramics were generated with a porous network and fiber structures, respectively. Keywords: Polymer-derived ceramics; Kraft pulp fibers; SiC
1
1. Introduction Silicon carbide is a non-oxide ceramic with attractive physicochemical and structural properties for a wide range of industrial applications. Depending on the architecture of the developed SiC, the applications can be varied. Indeed, porous SiC can be used as catalyst supports [1] or separation membranes [2], while SiC fibers are utilized for reinforcement of composites [3]. There are several techniques to produce a designed SiC [4-6]. In recent years, biotemplating is increasingly recommended to produce ceramic composite materials using natural templates like wood, organic fibers, cellulose fibers, etc. [7,8]. The cellular architecture of native wood materials, such as lignocellulosic fibers, was optimized through biomimetic microstructures, which are much more complex and difficult to produce artificially. However, these methods require a two-step high-temperature treatment to obtain the SiC ceramic material [9]. In this study, only one heat treatment was performed in order to obtain an organized SiC. For that, Kraft pulp fibers (KPF) and O-propargylated Kraft pulp fibers (PKPF), Figure 1a) are used as a sacrificial template to be impregnated with a preceramic hyperbranched polycarbosilane (PCS), synthesized in situ thanks to a hydrosilylation reaction. The alkyne functionalization was chosen to evaluate the possible reaction between PKPF and the polymer under construction, and to observe the impact on the final ceramic structure. Additionally, the thermal behavior of the fibers as well as the composite systems was investigated.
2. Experimental 2.1. Fabrication of the composite system For the preparation of the composite system, tetraallylsilane (TAS) (C12H20Si, 97% purity), and 1,4-bis(dimethylsilyl)benzene (BDSB) (C6H4[SiH(CH3)2]2, 97% purity) were used to synthesize a hyperbranched polymer via a hydrosilylation reaction (Figure 1b) in the presence of KPF or PKPF. For this, 30 mg of KPF (bleached softwood kraft pulp supplied by Kruger Wayagamack, Trois-Rivières Canada) and PKPF (see Supporting Information) were placed separately in two beakers, each containing 4 mL of toluene (99.5% purity). They were then subjected to an ultrasound bath for 15 minutes to promote the dispersion of fibers. Then, 491 µL of TAS (2.12 mmol) and 959 µL of BDSB (4.3 mmol) were added to each mixture, in a 20 mm diameter mold (i.e. 95.7 vol% of ceramic precursors and 4.3 vol% of fibers). Finally, 70 µL of a solution containing 450 µL of toluene and 50 µL of Karstedt catalyst (0.11 mmol) were added dropwise to catalyze the hydrosilylation reaction. After 24 hours, a gel formation was observed, surrounding the fibers. This led to samples with an average thickness of 1.7 mm. The propargylation of KPF is described in supporting information.
2
Fig. 1. Functionalization of KPF (a) and the hydrosilylation reaction leading to the PCS (b)
2.2. Characterizations 2.2.1. Fibers The propargylation was highlighted based on the FT-IR results of Pierre Antoine Faugeras et al. [10]. The thermal behavior of KPF and PKPF was investigated using a thermogravimetric -1
−1
analyzer (STA 449F3-Netzsch 1400 °C, argon flow: 20 mL.min , Heating rate (v): 10 °C.min ) coupled with a Mass Spectrometer (Omnistar, Balzers Instrument).
2.2.2. Composite system Phase identification was carried out by X-ray diffraction on powders (Bruker D8, Germany) using the CuKα radiation. The microstructures of the specimens before and after heat treatment were observed using Scanning Electron Microscopy (XL 30Philips TM, Eindhoven, Netherlands). The thermal behavior of the composites (KPF + PCS = C1) and (PKPF + PCS = C2) were investigated using a thermogravimetric analyzer (STA 449F3-Netzsch 1400 °C, argon -1
flow: 20 mL.min ) with a heating rate of 5 °C.min 10 °C.min
−1
−1
to 300 °C (2 h temperature hold) and then
to 1400 °C (1 h temperature hold). This TGA was also coupled with a Mass
Spectrometer (Omnistar, Balzers Instrument) to determine the species released during heating.
3. Results and discussion 3.1. Thermal behavior of fibers The thermal behavior of the fibers was studied (Figure 2). DSC analyses revealed that the two types of fibers have a similar behavior, so only the KPF DSC curve is presented. It is observed that all the fibers are consumed after heating up to 1400 °C and three domains are detected. Between 30 and 260 °C (domain I), a low weight loss of 8% is accompanied by a fairly exothermic event at 106 °C which coincides with water boiling temperature. Indeed, the MS highlights ionized fragments at m/z = 18 (H2O) resulting from dehydration of the cellulose [11]. Between 260 and 380 °C (domain II), a significant weight loss of 76% is observed, with an intense endothermic phenomenon at 346 °C. In this domain, various MS volatile fragments are
3
+
+
detected at m/z = 17 (OH ); 18 (H2O); 29 (C2H5 ) and 44 (CO2) [11]. In these 2 domains, KPF and PKPF show similar TGA-DSC and MS results. Nevertheless, a difference appears in the temperature range between 400 and 800 °C (domain III). Indeed, KPF tend to be degraded sooner than PKPF. MS analyses of the two fibers detect volatile products at m/z = 44 (CO2) as +
well as ionized fragments at m/z = 43 (C2H3O ). In the temperature range between 400 and 800 °C, the propargylation definitely delays the thermal degradation of PKPF.
Fig. 2. TGA-DSC of KPF and PKPF treated at 1400 °C (top), and TGA-DSC-MS of the composites (bottom)
4
3.2. Thermal behaviors of the composite systems The composite systems were analyzed by TGA-DSC-MS following the same thermal cycle considered for the pyrolysis (Figure 2). DSC analyses revealed that the two types of composite behave similarly, so only the DSC curve of the composite with PKPF was presented. The ceramic yield of the composite with PKPF is somewhat higher (24%) than the one with KPF (20%). The TGA shows 4 domains of weight loss for both systems. Domain I’ presents a weight loss of 10% for C2 and 6% for C1. These last are accompanied by an exothermic event at 52.5 min (294 °C). MS analyses highlight volatile fragments at m/z = 44 (CO2) for the two types of +
composite. In addition to CO2, the ionized fragment at m/z = 42 (C3H6 ) was detected in the case of C2 which explains its greater weight loss. In domain (II’), no weight loss was observed. This corresponds to the structuration of the material. Domain (III’) shows a weight loss of 59% for C2 and 68% for C1. These weight losses are accompanied by a strong exothermic event at +
+
182.5 min (385 °C). The MS detects ionized fragments at m/z = 15 (CH3 ); 26 (C2H2 ); 41 +
+
+
+
(C3H5 ); 42 (C3H6 ); 73 (Si-C3H9 ); 43 (C2H3O ) and CO2 at m/z = 44. These signals are the results of the fragmentation of both the fibers and the polycarbosilane and they are detectable in the two composites. In domain (IV’) a small weight loss of 7% for C2 and 5% for C1 are noticed, related to the CO2 and CH3 releases. The composites were pyrolyzed following the same heating cycle as TGA. XRD analyses, of the two composites emphasize the presence of β-SiC slightly crystallized or nano-crystallized (see Supporting Information). A broad signal at low angles was detected, and may be due to the residual amorphous carbon phase in the specimens.
3.3. Morphologies of the composites Before pyrolysis (Figure 3), considering PKPF, the PCS is formed on the surface of the fibers or it coats the entire fiber and matches its shape. In parallel, (Figure 3a) shows that the KPF are trapped within the polymer matrix. To explain this difference of behavior, an analysis by FT-IR spectroscopy was performed, but it did not allow us to clearly testify the reaction between the alkyne function of PKPF and the Si-H bond of the BDSB. After pyrolysis, C1 displays both dense and porous areas. These present a non-homogenous pore size distribution (from 20 to 60 µm for small pores, and from 80 to 200 µm for the large ones), which may be due to the removal of fibers during the ceramization of the PCS. For C2, both dense areas and fibrous SiC areas are observed. It may arise from the ceramization of the PCS which impregnated the fibers and imitated its shape, and led to a replica of the original fiber-based template.
5
Fig. 3. SEM images of C1 (a) and C2 (b) before pyrolysis, C1 (c) and C2 (d) after pryrolysis
4. Conclusion In this study, KPF and PKPF were used as a natural template to be impregnated by a PCS synthesized in-situ thanks to a hydrosilylation reaction. The composite systems were characterized by TGA-DSC-MS and SEM to evaluate their thermal behavior and morphology. Depending on the initial template, either KPF or PKPF, a composite was obtained, with a porous network or fiber structures of SiC, respectively. These results highlight the likely binding between the polymer and the alkyne functions for C2, and would allow for the future development of controlled designed materials, from defined natural templates. These latter could be used either as catalyst supports (porous structure), or as fibers reinforcement of composites (fiber structure).
References [1] M. J. Ledoux, C. Pham-Huu, Silicon Carbide: A Novel Catalyst Support for Heterogeneous Catalysis, CATTECH 5 (2001) 226-246. [2] M. Fukushima, Y.Zhou, H. Miyazaki, Y. Yoshizawa, K. Hirao, Microstructural Characterization of Porous Silicon Carbide Membrane Support With and Without Alumina Additive , J. Am. Ceram. Soc. 89 (2006) 1523-1529. [3] Y. Gou, H. Wang, K. Jian, C. Shao, X. Wang, Preparation and characterization of SiC fibers with diverse electrical resistivity through pyrolysis under reactive atmospheres, J. Eur. Ceram. Soc. 37 (2017) 517-522. [4] J.H. Eom, Y.W. Kim, S. Raju, Processing and properties of macroporous silicon carbide ceramics: A review, J. Asian Ceram. Soc. 1 (2013) 220-242.
6
[5] Y.W. Kim, J.H. Eom, C. Wang, C.B. Park, Processing of Porous Silicon Carbide Ceramics from Carbon-Filled Polysiloxane by Extrusion and Carbothermal Reduction, J. Am. Ceram. Soc. 91 (2008) 1361-1364. [6] Y.J. Jin, Y.W. Kim, Low Temperature Processing of Highly Porous Silicon Carbide Ceramics with Improved Flexural Strength, J. Mater. Sci. 45 (2010) 282-285. [7] P. Greil, Biomorphous ceramics from lignocellulosics, J. Eur. Ceram. Soc. 21 (2001) 105118. [8] A.R. Maddocks, A.T. Harris, Biotemplated synthesis of novel porous SiC, Mater. Lett. 63 (2009) 748-750. [9] H. Sieber, C. Hoffmann, A. Kaindl, P. Greil, Biomorphic Cellular Ceramics , Adv. Eng. Mater. 2 (2000) 105-109. [10] P.A. Faugeras, P.H. Elchinger, F. Brouillette, D. Montplaisir, R. Zerrouki, Advances in cellulose chemistry - microwave-assisted synthesis of propargylcellulose in aqueous medium, Green Chem.14 (2012) 598-600. [11] D. López-González, M. Fernandez-Lopez, J.L. Valverde, L. Sanchez-Silva, Thermogravimetric-mass spectrometric analysis on combustion of lignocellulosic biomass, Bioresour.Technol. 143 (2013) 562-574.
7
8
An easy polymerization of carbosilanes was carried out with KPF via hydrosilylation Porous or fibrous SiC were obtained from natural templates and preceramic polymers The fiber functionalization directly impacts the final microstructure of the composites
9