Co-reporter:Yuan Hu;Biao Wang;Keqing Zhou;Bibo Wang
Industrial & Engineering Chemistry Research August 6, 2014 Volume 53(Issue 31) pp:12355-12362
Publication Date(Web):Publication Date (Web): July 8, 2014
DOI:10.1021/ie502232a
CuMoO4/Zn–Al layered double hydroxide hybrids were synthesized by an ion-exchange and precipitation route. The results of X-ray diffraction (XRD) and transmission electron microscopy–energy-dispersive X-ray spectroscopy (TEM–EDS) analyses demonstrated the successful fabrication of CuMoO4/LDH hybrids. Subsequently, CuMoO4/LDH hybrids with different loadings were introduced into a polypropylene (PP) matrix by a master-batch-based melt-blending method for properties enhancement. With a CuMoO4/LDH hybrid loading of 5.0 wt %, the initial decomposition temperature of the PP composite increased by 61 °C. Differential scanning calorimetry (DSC) showed that the glass transition temperature (Tg) and the melting temperature (Tm) were both increased for PP composites. Moreover, according to microcombustion calorimetry (MCC) results, incorporation of CuMoO4/LDH hybrids markedly reduced the peak heat release rate (pHRR) and the total heat release (THR). Laser Raman spectroscopy (LRS) and scanning electron microscopy (SEM) images of the char residues of PP composites showed that the addition of CuMoO4/LDH hybrids into the PP matrix results in the formation of more stable and continuous char than LDH. The dramatic properties enhancement of PP composites is primarily due to the synergistic effects between CuMoO4 and LDH nanosheets: the adsorption and barrier effect of LDH nanosheets slowed the thermal degradation of the polymer matrix and inhibited the heat and flammable gas release, whereas CuMoO4 catalyzed the formation of more stable and graphitized char, which further improved the thermal and flame-retardant properties of PP composites.
Co-reporter:Longxiang Liu, Ying Pan, Zhou Wang, Yanbei Hou, Zhou Gui, and Yuan Hu
Industrial & Engineering Chemistry Research August 30, 2017 Volume 56(Issue 34) pp:9429-9429
Publication Date(Web):August 9, 2017
DOI:10.1021/acs.iecr.7b02303
Hypophosphorous acid-modified chitosan (PCS), as a novel phosphorus-containing chitosan derivative, was first successfully synthesized and characterized by Fourier transform infrared spectrometry and X-ray photoelectron spectroscopy. Subsequently, thin films of the ecofriendly PCS and branched polyethylenimine were deposited on polyester–cotton (PTCO) blends by the layer-by-layer assembly technique, in an effort to enhance their thermal properties and fire resistance properties. Thermogravimetric analysis, thermogravimetric analysis–Fourier transform infrared spectrometry, scanning electron microscopy, and horizontal flame test (HFT) were used to investigate the quality of the coatings as well as their fire resistance performance. The thermal and thermal oxidation stabilities at high temperature were enhanced for all coated PTCO blends. During the HFT, the afterglow phenomenon was eliminated for all coated blends, and self-extinguishing was achieved for the PCS2-20BL sample. It was found that the enhancement of the intumescent effect by the high phosphorus content in these coatings was conducive to achieving this superior performance.
Co-reporter:Yanbei Hou, Weizhao Hu, Xia Zhou, Zhou Gui, and Yuan Hu
Industrial & Engineering Chemistry Research August 2, 2017 Volume 56(Issue 30) pp:8778-8778
Publication Date(Web):July 11, 2017
DOI:10.1021/acs.iecr.7b01906
In this work, flowerlike nickel 2-methylimidazole metal–organic framework (Ni-MOF) was prepared by a solvothermal method. Vertically aligned Ni-MOF was fabricated from graphene oxide (GO) solution in the same way. The combination of GO and Ni-MOF (GOF) obviously suppressed the agglomeration of Ni-MOF sheets. As-synthesized, GOF has bigger pore volume and specific surface area, which are beneficial for volatile degradation products adsorption. It is noteworthy that the addition of GOF obviously reduced the fire hazard of polystyrene (PS). More than 33% decrease in the peak heat release rate for the PS/GOF composite was obtained when the content of the additives is only 1.0 wt %. Meanwhile, the reductions of total smoke and CO production were also prominent during the combustion of PS/GOF, respectively 21% and 52.3% decreases compared with that of pure PS. The synergism effects between layered GO and porous Ni-MOF realized the improved performances of PS. Thus, this work paves a feasible pathway to design efficient flame retardants for enhancing fire safety of polymers.
Co-reporter:Yanbei Hou, Weizhao Hu, Zhou Gui, Yuan Hu
Composites Science and Technology 2017 Volume 152(Volume 152) pp:
Publication Date(Web):10 November 2017
DOI:10.1016/j.compscitech.2017.08.032
Co–based metal-organic framework with phosphorus-containing structure (P-MOF) was synthesized by a facile hydrothermal reaction and was first added into epoxy resin (EP) to enhance its fire safety, including flame retardancy, toxicity reduction, and smoke suppression. It was found that the values of peak heat release rate and total heat release of EP were decreased by 28% and 18.6% respectively at 2 wt% content of P-MOF. Meanwhile, the notable reductions of total smoke production and total CO yield were also observed from results of cone calorimeter and the steady state tube furnace, decreased by 15% and 52% respectively. Due to the absorption and catalytic effect of P-MOF and its residues, the release of organic volatiles and CO generated during the pyrolysis process of EP was significantly suppressed. Based on the analysis of gas and condensed phase, the possible mechanism of the enhanced fire safety was proposed as the combination of the adsorption and catalytic effect of P-MOF, which provides a promising application of MOFs to enhance the fire safety of polymer materials.Download high-res image (293KB)Download full-size image
Co-reporter:Wei Wang, Panyue Wen, Jing Zhan, Ningning Hong, Wei Cai, Zhou Gui, Yuan Hu
Polymer Degradation and Stability 2017 Volume 144(Volume 144) pp:
Publication Date(Web):1 October 2017
DOI:10.1016/j.polymdegradstab.2017.09.011
A novel charring agent (PEPAPC) containing pentaerythritol and triazine structure, was successfully prepared via the nucleophilic substitution reaction of cyanuric chloride, 2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane-4-methanol (PEPA), and piperazine. Then, different proportions of PEPAPC and ammonium polyphosphate (APP) were added into polypropylene (PP) at a 20% total loading via melt blending. The results of limiting oxygen index (LOI), vertical burning test (UL-94), thermogravimetric analysis (TGA) and cone calorimeter test revealed that PEPAPC/APP system could effectively enhance the thermal stability and flame retardance of PP. When the weight ratio of APP to PEPAPC was 3:1 with a 20% loading (PP6), the PP composite achieved the highest LOI value of 28% and passed the vertical burning test (UL-94) V-0 rating. Meanwhile, PP6 showed the highest amount of char residues via TGA test and the lowest PHRR (253 kW/m2) via cone calorimeter test. Moreover, Scanning electron microscopy (SEM) also indicated that PEPAPC/APP system benefited to the formation of more compact char layer which hindered the transfer of volatiles and heat during burning. The investigation of their water resistance demonstrated that the PP6 still obtained a UL-94 V-0 rating after 72 h dipping in hot water.
Co-reporter:Yanbei Hou, Weizhao Hu, Zhou Gui, and Yuan Hu
Industrial & Engineering Chemistry Research 2017 Volume 56(Issue 8) pp:
Publication Date(Web):February 3, 2017
DOI:10.1021/acs.iecr.6b04920
In this work, iron-based and cobalt-based metal–organic frameworks (MOFs) were successfully synthesized by a facile solvothermal method. The obtained MOFs were added into polystyrene (PS) as flame retardants for the first time. The results of thermal gravimetric analysis and cone calorimetry indicated the addition of MOFs significantly enhanced the thermostability and flame retardancy of the PS composites. Compared with that of neat PS, greater than 14% and 28% decreases in the peak heat release rate were observed for PS/Fe-MOF and PS/Co-MOF, respectively, suggesting a flame retardant effect of MOFs. Based on thermogravimetric analysis–infrared spectrometry results and the analysis of combustion residues, the possible mechanism of the enhanced thermostability and flame retardancy of the PS composites was proposed as the combination of thermal barrier effect and catalytic effect of MOFs, which would allow promising application in the development of fire safety polymer materials.
Co-reporter:Yanbei Hou, Weizhao Hu, Zhou Gui, Yuan Hu
Composites Part A: Applied Science and Manufacturing 2017 Volume 100(Volume 100) pp:
Publication Date(Web):1 September 2017
DOI:10.1016/j.compositesa.2017.05.034
Bi2Se3 nanosheets with few layers have been successfully synthesized by a practical and mass-producible wet chemical method in this work. as-prepared nanosheets showed excellent compatibility with polyethylene (PE), which was attributed to the polyvinylpyrrolidone (PVP) encapsulated structure, generated during preparation process. The “interface”, composed by PVP and PE molecular chains, enhanced the surface interaction between Bi2Se3 nanosheets and PE matrix, and thus improved the mechanical properties. Yield modulus of PE increased remarkably even at low loadings of nanofillers. The thermal stability and flame retardancy of PE host were significantly enhanced, including at least 60 °C increase in Ti, 37.6% and 20% decrease in pHRR and THR respectively. Meanwhile, the release of smoke and CO for PE/Bi2Se3 nanocomposites was suppressed during combustion. These phenomena mainly caused by the barrier effect of Bi2Se3. Thus, Bi2Se3 nanosheets could be potentially used to prepare functional polymers for certain applications.
Co-reporter:Yongqian Shi, Bibo Wang, Lijin Duan, Yulu Zhu, Zhou Gui, Richard K. K. Yuen, and Yuan Hu
Industrial & Engineering Chemistry Research 2016 Volume 55(Issue 28) pp:7646-7654
Publication Date(Web):June 24, 2016
DOI:10.1021/acs.iecr.6b01237
Graphitic carbon nitride (g-C3N4) nanosheets are endowed with extraordinary chemical and thermal stability and good optical and photoelectrochemical properties and are expected to be used in a wide range of fields. The direct dispersion of hydrophobic g-C3N4 nanosheets in water or organic solvents without the assistance of dispersing agents is considered to be a great challenge. Here we report novel g-C3N4/organic-modified montmorillonite (OMMT) nanohybrids, which were synthesized through electrostatic interaction and then introduced into polystyrene (PS) matrix to fabricate nanocomposites by a simple solvent blending–precipitation method. Hybridizing g-C3N4 with OMMT could easily form stable aqueous colloids through electrostatic stabilization. These nanohybrids were evenly dispersed in PS and showed strong interfacial interactions with the polymer matrix. It is noted that the generation of total gaseous products was dramatically inhibited by combining g-C3N4 with OMMT. Moreover, flame retardancy was improved upon incorporation of the nanohybrids into PS host. These improvements were due to the strong interactions at interface of ternary systems, synergism between g-C3N4 and OMMT, and physical barrier effect of the two components. This work provides a new pathway to manufacture well-dispersed polymeric materials with enhanced fire safety.
Co-reporter:Lijin Duan, Hongyu Yang, Lei Song, Yanbei Hou, Wei Wang, Zhou Gui, Yuan Hu
Polymer Degradation and Stability 2016 Volume 134() pp:179-185
Publication Date(Web):December 2016
DOI:10.1016/j.polymdegradstab.2016.10.004
A novel phosphorus/nitrogen-containing hyperbranched polymer (PN-HBP) was synthesized via esterification reaction of 2-carboxyethyl (phenyl) phosphinic acid (CEPPA) and tris (2-hydrooxyethyl) isocyanurate (THEIC). PN-HBP was characterized by Fourier transform infrared (FTIR) spectrometry and 1H nuclear magnetic resonance (1H NMR) spectrometry. Its initial decomposition temperature (T−5wt%) is around 300 °C as the thermogravimetric analysis (TGA) showed. The flame-retardant polypropylene (PP) composites were prepared with the combination of PN-HBP and ammonium polyphosphate (APP) via melt blending. A higher limiting oxygen index (LOI) and a V-0 rating in the UL-94 vertical burning test were realized, indicating an apparent synergistic effect. The peak heat release rates (PHRR) of composites were reduced significantly compared with that of PP. The structure of the char residue was tested by Raman spectroscopy, indicating that the combination of PN-HBP and APP can prompt the formation of graphitized carbon layers and therefore improves the flame-retardancy of the PP composite.
Co-reporter:Lijin Duan, Hongyu Yang, Yongqian Shi, Yanbei Hou, Yulu Zhu, Zhou Gui, and Yuan Hu
Industrial & Engineering Chemistry Research 2016 Volume 55(Issue 38) pp:10218-10225
Publication Date(Web):September 5, 2016
DOI:10.1021/acs.iecr.6b02428
A novel branched phosphorus-containing flame retardant, CEPO, was successfully synthesized by a simple aqueous reaction of carboxyethyl-phenyl hypophosphorous acid and tris(hydroxymethyl) phosphine oxide. Combining with ammonium polyphosphate, CEPO was applied into poly(butylene terephthalate) to fabricate the composites. The results indicated that both peak heat release rate and total heat release were reduced significantly. Moreover, the higher weight proportion of CEPO to ammonium polyphosphate, the higher flame retardant efficiency was. And high limiting oxygen index values and UL-94 vertical burning test ratings were realized. Thermogravimetric analysis–Fourier transform infrared spectra detected the existence of PH3, which helps to understand the flame-retardant mechanism in the gas phase. The composites formed much residue during the combustion, which is helpful to retard the heat flow as scanning electronic microscope photos indicate.
Co-reporter:Keqing Zhou, Yixin Hu, Jiajia Liu, Zhou Gui, Saihua Jiang, Gang Tang
Materials Chemistry and Physics 2016 Volume 178() pp:1-5
Publication Date(Web):1 August 2016
DOI:10.1016/j.matchemphys.2016.05.002
•The LDH/MoS2 hybrids were facilely synthesized by self-assembly method.•The flame retardant efficiency of LDH/MoS2 hybrids in PVA was significantly enhanced.•It is a promising strategy for improving the flame retardant efficiency of MoS2.In present study, the layered double hydroxide/MoS2 hybrids are facilely synthesized by self-assembly of exfoliated MoS2 nanosheets and layered double hydroxide nanoplates via electrostatic interaction, with the aim of combining their physical and chemical functionalities to form a promising nanofiller for flame retardancy in polymer composites. The structure and morphology of the layered double hydroxide/MoS2 hybrids are probed by X-ray diffraction and transmission electron microscopy. Subsequently, the hybrids are incorporated into poly (vinyl alcohol) to serve as reinforcements. The flame retardant efficiency of MoS2 nanosheets in poly (vinyl alcohol) is significantly enhanced after the incorporation of layered double hydroxide nanoplates, which can be explained by the forming of a compact and uniform char during combustion.
Co-reporter:Yongqian Shi, Weiyi Xing, Bibo Wang, Ningning Hong, Yulu Zhu, Chengming Wang, Zhou Gui, Richard K.K. Yuen, Yuan Hu
Materials Chemistry and Physics 2016 Volume 177() pp:283-292
Publication Date(Web):1 July 2016
DOI:10.1016/j.matchemphys.2016.04.029
•APP/g-C3N4 hybrids were prepared for the first time.•APP/g-C3N4 hybrids showed the high residual content at high temperature.•Both thermal stability and flame retardancy of PS/APP/g-C3N4 composites were enhanced remarkably.A series of graphitic carbon nitride (g-C3N4) wrapped ammonium polyphosphate (APP) (CNAPP) were firstly prepared, and then incorporated into polystyrene (PS). The results indicated the successful wrapping of APP by g-C3N4. The CNAPP exhibited the higher thermal stability than pure APP. Enhanced interfacial interactions between CNAPP and PS were obtained upon introduction of CNAPP. The thermal stability of PS/CNAPP composites was significantly improved, compared with that of PS containing an equal amount of APP. Moreover, cone results showed that the heat release rate and total heat release were reduced greatly for PS/CNAPP20. It was confirmed that the formation of POC and PNC structures could remarkably improve the stability of char layer and thus result in the better flame retardancy of CNAPP, besides the enhanced thermal stability. The work provides a new paradigm for potential application of APP in polymeric materials.Download high-res image (249KB)Download full-size image
Co-reporter:Yongqian Shi, Ze Long, Bin Yu, Keqing Zhou, Zhou Gui, Richard K. K. Yuen and Yuan Hu
Journal of Materials Chemistry A 2015 vol. 3(Issue 33) pp:17064-17073
Publication Date(Web):10 Jul 2015
DOI:10.1039/C5TA04349B
Significant improvements in thermal and flame retardant properties of polymeric materials at low loadings hold tremendous promise for fire safety materials. In the present work, a highly effective graphitic carbon nitride/acidized multi-walled carbon nanotube (g-C3N4/aMWCNT) bilayer was deposited on a PS sphere for reducing its fire hazards. The PS sphere allowed the intimate assembly of the g-C3N4/aMWCNT bilayer on its surface through electrostatic interactions. Structural and morphological characterization revealed the successful assembly of PS/g-C3N4/aMWCNT systems. Enhanced thermal stability and flame retardancy (e.g. a decrease of ca. 45% and 47% in HRR and THR, respectively) were obtained for the ternary assembled systems instead of the binary materials. The phenomena were caused by two reasons: g-C3N4/aMWCNT bilayers induced the construction of the “tortuous path” which impeded the permeation of heat and the escape of pyrolysis volatile products; on the other hand, stacked g-C3N4 nanosheets or thermolabile aMWCNTs with an uncompact network structure led to poor thermal stability and fire resistance. Thus, this work paves a potential pathway to design efficient assembled fire-retardant systems for fire safety.
Co-reporter:Keqing Zhou, Jiajia Liu, Yongqian Shi, Saihua Jiang, Dong Wang, Yuan Hu, and Zhou Gui
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 11) pp:6070
Publication Date(Web):March 5, 2015
DOI:10.1021/acsami.5b00762
In the present study, carbon nanotubes (CNTs) wrapped with MoS2 nanolayers (MoS2–CNTs) were facilely synthesized to obtain advanced hybrids. The structure of the MoS2–CNT hybrids was characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy measurements. Subsequently, the MoS2–CNT hybrids were incorporated into EP for reducing fire hazards. Compared with pristine CNTs, MoS2–CNT hybrids showed good dispersion in EP matrix and no obvious aggregation of CNTs was observed. The obtained nanocomposites exhibited significant improvements in thermal properties, flame retardancy and mechanical properties, compared with those of neat EP and composites with a single CNT or MoS2. With the incorporation of 2.0 wt % of MoS2–CNT hybrids, the char residues and glass transition temperature (Tg) of the EP composite was significantly increased. Also, the addition of MoS2–CNT hybrids awarded excellent fire resistance to the EP matrix, which was evidenced by the significantly reduced peak heat release rate and total heat release. Moreover, the amount of organic volatiles from EP decomposition was obviously decreased, and the formation of toxic CO was effectively suppressed, implying the toxicity of the volatiles was reduced and smoke production was obviously suppressed. The dramatically reduced fire hazards were generally ascribed to the synergistic effect of MoS2 and CNTs, containing good dispersion of MoS2–CNT hybrids, catalytic char function of MoS2 nanolayers, and physical barrier effects of MoS2 nanolayers and CNT network structure.Keywords: CNTs; epoxy resin; fire hazards; MoS2; nanolayers; thermal properties
Co-reporter:Saihua Jiang, Guohua Chen, Yuan Hu, Zhou Gui, and Zhijia Hu
Industrial & Engineering Chemistry Research 2015 Volume 54(Issue 17) pp:4737-4747
Publication Date(Web):April 20, 2015
DOI:10.1021/ie5050549
A novel poly(methyl methacrylate) (PMMA)-based nanocomposite combined with a reactive flame retardant (tetramethyl (3-(triethoxysilyl) propyl-azanediyl) bis(methylene) diphosphonate (TMSAP)) and organo-modified layered aluminophosphate (OLAP) was synthesized by the sol–gel method. The structure of the nanocomposite achieves maximal integration of both merits of each component, such as silane cross-linking function and dehydration charring effect of TMSAP and physical barrier effect and catalytic-charring effect of OLAP, which promotes cross-linked network formation, improves the quality and quantity of char, and inhibits the heat, oxygen, and mass transfer, leading to significant enhancements of scratch resistance, thermal stability, and flame retardancy. Compared to PMMA, the nanocomposites maintain high transparency and exhibit increased shore hardness by 90%, glass transition temperature by 13 °C, and half degradation temperature by 105.1 °C; in addition, peak heat released rate decreased by 59.1%. This work demonstrates the simultaneous enhancement of flame retardancy, thermal properties, and mechanical performance of polymers.
Co-reporter:Yongqian Shi, Yulu Zhu, Bin Yu, Zhou Gui, Shike She, Richard K. K. Yuen, Hui Liu and Yuan Hu
RSC Advances 2015 vol. 5(Issue 52) pp:41835-41838
Publication Date(Web):20 Apr 2015
DOI:10.1039/C5RA02787J
Spinel ZnCo2O4 has shown great superiorities in the fields of catalyst and energy. However, its applications in improving thermal stability of polymeric materials are rarely reported. In this work, polystyrene/graphite-like carbon nitride/ZnCo2O4 composites were prepared, and the mechanism for their improved thermal stability was discussed in the sight of catalysis.
Co-reporter:Qiangjun Zhang, Jing Zhan, Keqing Zhou, Hongdian Lu, Wenru Zeng, Anna A. Stec, T. Richard Hull, Yuan Hu, Zhou Gui
Polymer Degradation and Stability 2015 Volume 115() pp:38-44
Publication Date(Web):May 2015
DOI:10.1016/j.polymdegradstab.2015.02.010
In recent years, carbon nanotubes (CNTs) have emerged as a promising candidate for improving the flame retardancy of polymer materials, as well as other physical properties. However, few researches have been focused on the influence of this nanoscale material on the combustion toxicity of polymer composites during combustion. In this work, the fire toxicity of polypropylene (PP) composites with intumescent flame retardants (IFRs) and CNTs has been investigated by a Purser Furnace apparatus, which is called steady state tube furnace (SSTF) and enables different fire stages to be created. The Thermo gravimetric analyzer (TGA) and derivative thermo gravimetric analysis (DTG) data indicate that the thermal stability of PP composites was increased by the addition of IFRs or CNTs. However, the SSTF results show that PP samples with IFR or CNTs or both, produced much more carbon monoxide (CO) compared to neat PP during all fire stages, resulting in a much lower CO2/CO ratio. Furthermore, an interesting finding is that the effect of CNTs on the smoke production and CxHy yield of the PP samples during the combustion changes with the combustion equivalence ratio. It indicates that the presence of CNTs promote the formation of smoke particulates from hydrocarbon, but this effect only exist when oxygen supply is not adequate. It is also concluded that the air ventilation and combustion temperature play significant roles in the fire effluent production of PP samples and the morphology of soot particulates.
Co-reporter:Jiajia Liu;Keqing Zhou;Panyue Wen;Bibo Wang;Yuan Hu
Polymers for Advanced Technologies 2015 Volume 26( Issue 6) pp:626-634
Publication Date(Web):
DOI:10.1002/pat.3497
This work reported the preparation and physical properties of biodegradable nanocomposites fabricated using polylactic acid (PLA) and multiple organic modified montmorillonite (MMT). In order to improve the chemical compatibility between PLA and Na-MMT, the surface of Na-MMT was first organically modified by cetyl trimethyl ammonium bromide (CTAB) and resorcinol bis(diphenyl phosphate) (RDP) using ion-exchange and adsorption technique. Both Fourier transform infrared and X-ray diffraction (XRD) results indicated that CTAB and RDP molecules were intercalated into the galleries of MMT sheets to enlarge the interlayer spacing. Then, the PLA/MMT nanocomposites were prepared by a simple melt-blending method. The XRD and TEM results of the nanocomposites indicated that the PLA polymer chains inserted into the galleries of co-modified MMT (C-MMT) and contained disorderedly intercalated layered silicate layers within a PLA matrix. The C-MMT nanolayers were homogenously dispersed in PLA matrix, resulting in various property enhancement. The fabricated PLA/C-MMT nanocomposites with 5.0 wt% addition showed significant enhancements (176%) in the storage modulus compared to that of neat PLA. The thermal stability and fire resistance were also remarkably improved. These improvements are probably because of both the physical barrier effect of the MMT nanosheets and charring effect of the C-MMT. Copyright © 2015 John Wiley & Sons, Ltd.
Co-reporter:Keqing Zhou, Jiajia Liu, Panyue Wen, Yuan Hu, Zhou Gui
Materials Research Bulletin 2015 67() pp: 87-93
Publication Date(Web):
DOI:10.1016/j.materresbull.2015.03.006
Co-reporter:Yongqian Shi, Keqing Zhou, Bibo Wang, Saihua Jiang, Xiaodong Qian, Zhou Gui, Richard K. K. Yuen and Yuan Hu
Journal of Materials Chemistry A 2014 vol. 2(Issue 2) pp:535-544
Publication Date(Web):01 Nov 2013
DOI:10.1039/C3TA13409A
Graphene (Gr)-based binary Gr–CoFe2O4 and Gr–CdS or ternary Gr–CoFe2O4/CdS nanohybrids were prepared via a facile solvothermal strategy. It was encouraging to find that the ternary Gr–CoFe2O4/CdS nanohybrids exhibited the highest photocatalytic degradation ability (80%) among all the photocatalysts. The significant enhancement in photodegradation under 40 W daylight lamp irradiation was attributed to graphene acting as a “bridge”, where electrons generated from CoFe2O4 were transferred to CdS by graphene and finally led to separation of electrons and holes. Interestingly, neat CoFe2O4 resulted in increasing concentration of methylene blue (MB) as the irradiation time increased. The phenomenon was ascribed to adsorption of MB molecules on CoFe2O4 in the dark and desorption from the photocatalyst during irradiation, confirmed by our ingenious experiment. Digital photos of the Gr–CoFe2O4/CdS hybrids in an external magnetic field indicated that the ternary photocatalyst could be easily separated from aqueous solution. The recycle measurements of the photocatalyst revealed that the ternary nanohybrids exhibited acceptable photocatalytic stability due to unstable decoration. This work would provide a new insight into the construction of visible light-responsive and magnetic separable photocatalysts with high performances.
Co-reporter:Yongqian Shi, Saihua Jiang, Keqing Zhou, Chenlu Bao, Bin Yu, Xiaodong Qian, Bibo Wang, Ningning Hong, Panyue Wen, Zhou Gui, Yuan Hu, and Richard K. K. Yuen
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 1) pp:429
Publication Date(Web):December 6, 2013
DOI:10.1021/am4044932
A series of sodium alginate (SA) nanocomposite films with different loading levels of graphitic-like carbon nitride (g-C3N4) were fabricated via the casting technique. The structure and morphology of nanocomposite films were investigated by X-ray powder diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy. Thermogravimetric analysis results suggested that thermal stability of all the nanocomposite films was enhanced significantly, including initial thermal degradation temperature increased by 29.1 °C and half thermal degradation temperature improved by 118.2 °C. Mechanical properties characterized by tensile testing and dynamic mechanical analysis measurements were also reinforced remarkably. With addition of 6.0 wt % g-C3N4, the tensile strength of SA nanocomposite films was dramatically enhanced by 103%, while the Young’s modulus remarkably increased from 60 to 3540 MPa. Moreover, the storage modulus significantly improved by 34.5% was observed at loadings as low as 2.0 wt %. These enhancements were further investigated by means of differential scanning calorimetry and real time Fourier transform infrared spectra. A new perspective of balance was proposed to explain the improvement of those properties for the first time. At lower than 1.0 wt % loading, most of the g-C3N4 nanosheets were discrete in the SA matrix, resulting in improved thermal stability and mechanical properties; above 1.0 wt % and below 6.0 wt % content, the aggregation was present in SA host coupled with insufficient hydrogen bondings limiting the barrier for heat and leading to the earlier degradation and poor dispersion; at 6.0 wt % addition, the favorable balance was established with enhanced thermal and mechanical performances. However, the balance point of 2.0 wt % from dynamic mechanical analysis was due to combination of temperature and agglomeration. The work may contribute to a potential research approach for other nanocomposites.Keywords: balance; g-C3N4 nanosheets; hydrogen bonds; mechanical property; sodium alginate; thermal stability;
Co-reporter:Saihua Jiang, Hongyu Yang, Xiaodong Qian, Yongqian shi, Keqing Zhou, Haiyan Xu, Xueying Shan, Siuming Lo, Yuan Hu, and Zhou Gui
Industrial & Engineering Chemistry Research 2014 Volume 53(Issue 10) pp:3880-3887
Publication Date(Web):2017-2-22
DOI:10.1021/ie4035863
A novel cross-linked poly(methyl methacrylate) (PMMA)-based copolymer was first synthesized by bulk copolymerization of methyl methacrylate (MMA) and 1-oxo-2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane-4-acrylate (PEPAA) at low temperature (80 °C), which is a facile and green method. The structure of PEPAA was confirmed by FTIR, 1H NMR, and 31P NMR. The morphology and structure of copolymers were characterized using FTIR and SEM. Due to the chain transfer during copolymerization, a cross-linked network is successfully introduced into the copolymers and the gel fraction increases as the PEPAA content increases, as evinced by the results from Soxhlet extraction and DMA. The copolymers exhibit relatively high transparency and significant improvements to the mechanical properties, thermal properties, and fire retardancy when compared to PMMA. From the mechanism analysis, the cross-linked network plays a key role in the improvements to the mechanical properties and thermal properties. For enhanced fire retardancy, char formation during degradation caused by PEPAA is the main factor.
Co-reporter:Keqing Zhou, Saihua Jiang, Yongqian Shi, Jiajia Liu, Biao Wang, Yuan Hu and Zhou Gui
RSC Advances 2014 vol. 4(Issue 76) pp:40170-40180
Publication Date(Web):18 Aug 2014
DOI:10.1039/C4RA02347A
A multigram-scale fabrication method was developed to modify molybdenum disulfide (MoS2) nanosheets with cetyl trimethyl ammonium bromide (CTAB), and the CTAB-modified MoS2 nanosheets (CTAB-MoS2) were applied to improve the properties of polymers. CTAB-MoS2 dispersed well in organic solvents and was incorporated into polystyrene (PS) by a masterbatch-based melt-blending method. The morphology, thermal behavior, fire resistance, and smoke suppression properties of the nanocomposites were studied. The CTAB-MoS2 nanosheets dispersed well in PS and exhibited a partial exfoliation structure. The incorporation of 3 wt% CTAB-MoS2 nanosheets led to an increase in thermal degradation temperature (43–60 °C) and char formation as well as a reduction of the peak heat release rate (PHRR) (20%). Moreover, the addition of CTAB-MoS2 nanosheets significantly decreased the smoke production rate (SPR), the peak specific extinction area (peak-SEA) values (52% reduction), and the gaseous products. The improvements in the thermal stability, fire resistance, and smoke suppression properties of PS nanocomposites were ascribed to good dispersion of modified MoS2 nanosheets, physical barrier effects, and catalytic char function of MoS2 nanosheets.
Co-reporter:Keqing Zhou, Qiangjun Zhang, Jiajia Liu, Biao Wang, Saihua Jiang, Yongqian Shi, Yuan Hu and Zhou Gui
RSC Advances 2014 vol. 4(Issue 26) pp:13205-13214
Publication Date(Web):28 Feb 2014
DOI:10.1039/C3RA46334F
As a graphene-like layered nanomaterial, molybdenum disulfide (MoS2) has gained intensive attention from the materials community. In our research, MoS2 is firstly modified with ferrocene (Fe–MoS2) on a large scale and then is used as a nanofiller to prepare PS composites by a masterbatch-based melt blending method. The aim of our present study is to study the synergistic effect of ferrocene and MoS2 on the thermal stability, fire resistance and smoke suppression properties of the PS composites. It was found that the thermal stability of the PS composite was obviously enhanced upon the introduction of 3.0 wt% Fe–MoS2. The cone test results indicated that the PS/Fe–MoS2 composites exhibited superior flame retardance to PS/MoS2 and PS/ferrocene composites. Furthermore, the addition of Fe–MoS2 could improve the smoke suppression properties of PS composites, as evidenced by the reduction of the carbon monoxide production rate and smoke production rate (SPR). The total flammable gaseous products from the PS composites were decreased which further led to the inhibition of smoke. Such a significant improvement in thermal stability, fire resistance and smoke suppression properties was mainly attributed to good dispersion of the modified MoS2 nanosheets, synergistic effects between ferrocene and MoS2 nanosheets, physical barrier effects of MoS2 nanosheets and the presence of ferrocene and MoS2 can promote char formation simultaneously.
Co-reporter:Saihua Jiang, Zhou Gui, Yongqian Shi, Keqing Zhou, Bihe Yuan, Chenlu Bao, Siuming Lo, Yuan Hu
Polymer Degradation and Stability 2014 Volume 107() pp:1-9
Publication Date(Web):September 2014
DOI:10.1016/j.polymdegradstab.2014.04.027
Bismuth subcarbonate ((BiO)2CO3·xH2O) nanoplate, a bismuth-containing layered nanomaterial, is successfully applied in improving fire safety properties of polymers for the first time. The introduction of (BiO)2CO3·xH2O (≤6.2 wt%) into poly(methyl methacrylate) (PMMA) matrix by in situ polymerization method enhances the thermal stability, flame retardancy and smoke suppression properties remarkably including increased onset degradation temperature (T0.1, by 58 °C) and mid-point degradation temperature (T0.5, by 24 °C), and decreased peak heat release rate, total heat release, toxic volatile organic products (VOP) and smoke density. Morphological studies of PMMA/(BiO)2CO3·xH2O nanoplate composites by Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) suggest that (BiO)2CO3·xH2O nanoplates are well dispersed in the PMMA matrix. Thermal decomposition behaviors investigated by Thermogravimetric analysis (TGA) and char analysis studied by Fourier transform infrared spectra (FTIR) demonstrate the catalytic charring effect of (BiO)2CO3·xH2O to PMMA matrix. Due to the char formation during degradation, the toxic VOP amount and smoke evolution from PMMA combustion are reduced. Meanwhile, thermal decomposition of (BiO)2CO3·xH2O can release carbon dioxide (CO2) and water, which was evidenced by thermogravimetric analysis/infrared spectrometry (TGA-IR) results. The (BiO)2CO3·xH2O nanoplates combines several flame-retardant strategies including the char formation, dilution effect of CO2 and water, and physical barrier effect, and thus enhance the thermal stability, flame retardancy and smoke suppression of PMMA/(BiO)2CO3·xH2O composites simultaneously.
Co-reporter:Keqing Zhou, Jiajia Liu, Biao Wang, Qiangjun Zhang, Yongqian Shi, Saihua Jiang, Yuan Hu, Zhou Gui
Materials Letters 2014 Volume 126() pp:159-161
Publication Date(Web):1 July 2014
DOI:10.1016/j.matlet.2014.04.040
•In this work, poly(methyl methacrylate)/MoS2 nanocomposites were prepared by a facile emulsion polymerization method.•The improvement in thermal stability of the nanocomposites is remarkable with only 1% MoS2 content.•The emulsion polymerization method opens a new avenue to fabricate MoS2-based polymer nanocomposites.In this work, poly(methyl methacrylate)/MoS2 nanocomposites were prepared by a facile emulsion polymerization method. X-ray diffraction (XRD), Fourier transform infrared (FTIR) and Transmission electron microscopy (TEM) results demonstrated that MoS2 is homogenously dispersed and partially exfoliated in a PMMA matrix. The improvement in thermal stability of the nanocomposites is remarkable with only 1% MoS2 content which is attributed to the physical barrier effect and the charring effect of the MoS2 nanosheets.
Co-reporter:Keqing Zhou;Saihua Jiang;Bibo Wang;Yongqian Shi;Jiajia Liu;Ningning Hong;Yuan Hu
Polymers for Advanced Technologies 2014 Volume 25( Issue 7) pp:701-710
Publication Date(Web):
DOI:10.1002/pat.3273
In this paper, three typical transition metal phosphide nanocrystallines (MxPy, M = Ni, Co, and Cu) were synthesized by a novel hydrothermal method, and their structures were characterized by X-ray diffraction and transmission electron microscopy. Then they were used as synergistic agents with intumescent flame retardant (IFR) to improve the fire safety of polypropylene (PP). Thermogravimetry analysis (TGA) results indicated that the introduction of these synergists could improve the thermal stability and char yields of the PP/IFR system. The addition of 2 wt.% Ni12P5 and Co2P increased the limiting oxygen index values of the PP/IFR system significantly from 28% to 36% and 34%, respectively, and the system could reach V-0 rating. The cone calorimeter test results revealed that the combination of transition metal phosphide nanocrystallines and IFR system could result in excellent flame retardancy. The incorporation of these synergists into IFR led to a remarkable influence on charring of PP composites as revealed by TGA and cone data. The morphological structure of char residue proved that the addition of transition metal phosphide nanocrystallines was capable of forming a compact and homogeneous char on the surface, which turned out to be of most importance for the flame retardancy. Thermogravimetric analysis/infrared spectrometry results indicated that the flame retardant mechanism of PP/IFR/MxPy (M = Ni, Co, and Cu) system was in the condensed phase rather than in the gas phase. Copyright © 2014 John Wiley & Sons, Ltd.
Co-reporter:Biao Wang;Keqing Zhou;Saihua Jiang;Yuan Hu;Z. Gui
Polymers for Advanced Technologies 2014 Volume 25( Issue 12) pp:1419-1425
Publication Date(Web):
DOI:10.1002/pat.3380
In this paper, three different kinds of typical transition metal molybdates (AMoO4, A = Co, Ni, Cu) were synthesized via a hydrothermal method. X-ray diffraction and scanning electron microscopy (SEM) were used to characterize their structures. Then, the synthesized molybdates were incorporated into acrylonitrile-butadiene-styrene (ABS) matrix via a masterbatch-based melt blending method. SEM images showed that transition metal molybdates (AMoO4, A = Co, Ni, Cu) are homogeneously dispersed in the ABS matrix. Thermogravimetric analysis (TGA) results indicated that the introduction of these transition metal molybdates (AMoO4, A = Co, Ni, Cu) could accelerate the degradation of ABS, especially for the CuMoO4. The initial thermal degradation temperatures are decreased by 9–12°C for ABS/CoMoO4 and ABS/NiMoO4 composites. But for the ABS/CuMoO4 composite, it is decreased by 45°C. Meanwhile, the peak of heat release rate is decreased by 10%–13% for ABS/CoMoO4 and ABS/NiMoO4 composites, and it is decreased by 26% for ABS/CuMoO4 composite. Moreover, TGA/infrared spectrometry was used to investigate the smoke suppression effect of CuMoO4 in ABS indirectly; it showed that the addition of CuMoO4 inhibits the release of hydrocarbons, aromatic compounds, and CO and promotes the generation of CO2. Copyright © 2014 John Wiley & Sons, Ltd.
Co-reporter:Keqing Zhou, Biao Wang, Jiajia Liu, Saihua Jiang, Yongqian Shi, Qiangjun Zhang, Yuan Hu, Zhou Gui
Materials Research Bulletin 2014 53() pp: 272-279
Publication Date(Web):
DOI:10.1016/j.materresbull.2014.02.029
Co-reporter:Biao Wang, Keqing Zhou, Saihua Jiang, Yongqian Shi, Bibo Wang, Zhou Gui, Yuan Hu
Materials Research Bulletin 2014 56() pp: 107-112
Publication Date(Web):
DOI:10.1016/j.materresbull.2014.04.066
Co-reporter:Saihua Jiang, Keqing Zhou, Yongqian Shi, Ningning Hong, Siuming Lo, Yuan Hu, and Zhou Gui
Industrial & Engineering Chemistry Research 2013 Volume 52(Issue 47) pp:16766-16773
Publication Date(Web):November 5, 2013
DOI:10.1021/ie402744s
2D lamellar aluminophosphate (LAP) is successfully exfoliated into nanolayers in polyurethane (PU) through the combination of organically modification and solution casting method. Morphological studies by XRD and TEM show that the exfoliated LAP nanolayers are dispersed well in the PU matrix. The introduction of small amounts of LAP nanolayers (≤5.0 wt %) results in obvious enhancements in the thermal properties and mechanical performance of PU/LAP nanocomposites. These enhancements are benefiting from the good dispersion and exfoliated morphology of stiff LAP nanolayers and strong interfacial interaction between LAP nanolayers and the matrix. LOI and MCC results indicate that the LAP nanolayers incorporated also improve the flame retardancy of nanocomposites. Detailed flame-retardant mechanism is proposed. Physical barrier effect of LAP nanolayers and the graphitized char formation catalyzed by LAP play key roles in the flame retardancy enhancement.
Co-reporter:Saihua Jiang, Yongqian Shi, Xiaodong Qian, Keqing Zhou, Haiyan Xu, Siuming Lo, Zhou Gui, and Yuan Hu
Industrial & Engineering Chemistry Research 2013 Volume 52(Issue 49) pp:17442
Publication Date(Web):November 21, 2013
DOI:10.1021/ie4028439
A novel acrylate monomer containing phosphorus and nitrogen— N,N-bis(2-hydroxyethyl acrylate) aminomethyl phosphonic acid diethylester (BHAAPE)—was first synthesized by the combination of the Kabachnik–Fields reaction and esterification, and then incorporated into epoxy acrylate (EA) resins through an ultraviolet (UV) curing process. The structure of BHAAPE was confirmed by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR). The functionalized epoxy acrylate (FEA) resins exhibit significantly enhanced flame retardancy, which were evidenced by LOI, microscale combustion calorimetry (MCC) and cone calorimetry testing (CCT). Thermogravimetric analysis (TGA) results show that the introduction of BHAAPE promotes degradation of the EA matrix and catalyzes its char formation. The thermal degradation mechanism of FEA was further investigated by RTIR and direct pyrolysis/mass spectroscopy (DP-MS). The char structure of FEA, as characterized by scanning electron microscopy (SEM), reveals that the BHAAPE acts as a good intumescent fire retardant in the enhanced flame retardancy. Based on the analysis for thermal degradation and char structure, a detailed flame-retardant mechanism was proposed.
Co-reporter:Keqing Zhou, Wei Yang, Gang Tang, Bibo Wang, Saihua Jiang, Yuan Hu and Zhou Gui
RSC Advances 2013 vol. 3(Issue 47) pp:25030-25040
Publication Date(Web):14 Oct 2013
DOI:10.1039/C3RA43297A
As a graphene-like layered nano-material, molybdenum disulfide (MoS2) has gained intensive attention from the materials fields. In our research, MoS2 and graphene sheets (GNS) were used as nanofillers to prepare polystyrene (PS) composites by masterbatch-melt blending. The morphology, thermal stability, fire resistance and smoke suppression properties of the PS composites were studied. The aim of our present study is to compare the effect of MoS2 and GNS on the thermal stability, fire resistance and smoke suppression properties of the PS composites. The cone test results indicate the PS/GNS composites exhibited superior flame retardance over PS/MoS2 composites. The results from TGA exhibits that the addition of MoS2 improved the thermal stability and char residues of the PS composites more obviously, When adding 3 wt% MoS2, T−5%, T−10% and T−50% of the composites are increased to 371, 390 and 428 °C, which are 39, 43 and 31 °C higher than those of PS/3% GNS composites. TG-IR results show that the main decomposition products of PS/MoS2 and PS/GNS composites are aromatic compounds and alkenyl units which are similar to those of pure PS. However, less flammable gas products are released relative to pure PS which further leads to the inhibition of smoke. The improvements in the thermal stability, fire resistance and smoke suppression properties of the PS composites are attributed to good dispersion, physical barrier effects of layered nanofillers and the presence of MoS2 which can promote char formation.
Co-reporter:Saihua Jiang, Zhou Gui, Yuan Hu, Keqing Zhou, Yangyang Dong, Yongqian Shi
Materials Chemistry and Physics 2013 Volume 141(Issue 1) pp:95-100
Publication Date(Web):15 August 2013
DOI:10.1016/j.matchemphys.2013.04.029
•Thermal properties of the PMMA/LAP composites are improved excellently.•The nanocomposites keep the high transparency in optical properties.•The graphitized char formation during heating plays a key role for the improvement.Poly(methyl methacrylate) (PMMA)/dodecylamine templated lamellar aluminophosphate (DDA-LAP) intercalated nanocomposites are prepared by in situ bulk polymerization of MMA. The intercalated structure is characterized. With the intercalation of DDA-LAP in PMMA matrix, the glass-transition temperatures of nanocomposites (Tg) are increased. The nanocomposites obtained keep relatively high transparency in optical property and have a significant improvement in mechanical properties and thermal stability. The mechanism for the properties enhancement is investigated. The strong interfacial interaction between the aluminophosphate layers and the PMMA chains, the homogeneously distribution and the graphitized char formation during heating are three key roles for the properties improvement.
Co-reporter:Keqing Zhou, Yongqian Shi, Saihua Jiang, Yuan Hu, Zhou Gui
Materials Letters 2013 Volume 98() pp:213-216
Publication Date(Web):1 May 2013
DOI:10.1016/j.matlet.2013.02.019
Cu2O/carbon sphere (CS) heterostructure was prepared via a relatively facile chemical reduction method, using a single-source molecule (cupric acetate) as precursor and CS as a support material. The heterostructure was characterized by X-ray powder diffraction, scanning electron microscope, and transmission electron microscopy. The performance of the Cu2O/CS heterostructure as photocatalyst was evaluated via using methyl orange (MO) as the probe molecule. The photocatalytic activity of Cu2O/CS heterostructure was improved obviously comparing with pure Cu2O and the possible reason was discussed. The results demonstrate the potential application of this easy synthesized method for photocatalyst preparation.Graphical highlightsHighlights► In this work, we have prepared Cu2O/CS heterostructure composites via a relatively facile chemical reduction method. ► The heterostructure was characterized by X-ray powder diffraction, scanning electron microscope, and transmission electron microscopy. ► The photocatalytic activity of Cu2O/CS heterostructure was improved obviously comparing with pure Cu2O and the possible reason was discussed.
Co-reporter:Keqing Zhou, Yongqian Shi, Saihua Jiang, Lei Song, Yuan Hu, Zhou Gui
Materials Research Bulletin 2013 48(9) pp: 2985-2992
Publication Date(Web):
DOI:10.1016/j.materresbull.2013.04.016
Co-reporter:Keqing Zhou, Saihua Jiang, Chenlu Bao, Lei Song, Bibo Wang, Gang Tang, Yuan Hu and Zhou Gui
RSC Advances 2012 vol. 2(Issue 31) pp:11695-11703
Publication Date(Web):02 Oct 2012
DOI:10.1039/C2RA21719H
As a graphene-like layered nano-material, molybdenum disulfide (MoS2) has gained much attention from the materials fields. In our research, MoS2/poly(vinyl alcohol) (PVA) nanocomposites are prepared by solvent blending method. The morphology, thermal properties, fire resistance properties and mechanical properties of the PVA/MoS2 nanocomposites are studied. MoS2 is homogeneously dispersed and partially exfoliated in the PVA matrix as indicated by X-ray diffraction (XRD) pattern, Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM) characterization. The thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) results indicate improved the thermal decomposition temperature and the glass transition temperature (Tg). The thermal degradation temperature is increased by 20–40 °C. Meanwhile, the peak of heat release rate (pHRR) and total heat release (THR) are decreased by 33% and 20%, respectively. Storage modulus at 40 °C is increased by 28%, and the tensile strength is increased by 24% upon addition of 1 wt% and 5 wt% MoS2. The improvements in the thermal properties, fire resistance properties and mechanical properties of PVA nanocomposites are attributed to the good dispersion of MoS2, physical barrier effects of MoS2 and strong interactions between PVA and MoS2.
Co-reporter:Yangyang Dong, Zhou Gui, Saihua Jiang, Yuan Hu, and Keqing Zhou
Industrial & Engineering Chemistry Research 2011 Volume 50(Issue 19) pp:10903-10909
Publication Date(Web):August 21, 2011
DOI:10.1021/ie200319e
Poly(methyl methacrylate)/hydroxyapatite nanorod (PMMA/HANR) composites were synthesized by in situ polymerization of methyl methacrylate (MMA) in a suspension of HANRs in ethanol. It was found that the thermal properties of the composites were improved effectively by increasing the inorganic HANR loading, especially when the amount of loaded HANRs was high enough (≥9.3 wt %). The experimental results showed that graphitized char was generated in the residue after thermal degradation of the composites in air at 550 °C for 0.5 h. The residues of the composites with higher inorganic loadings formed a compact and continuous network structure made up of inorganic fillers and carbonaceous char. This indicates that the carbonization behavior of HANRs in PMMA matrix leads to improvement of the thermal properties of the polymer.
Co-reporter:Zhou Gui, Jixin Zhu, Yuan Hu
Materials Chemistry and Physics 2010 Volume 124(Issue 1) pp:243-247
Publication Date(Web):1 November 2010
DOI:10.1016/j.matchemphys.2010.06.025
β-Co(OH)2 hollow-ware stacked nanosheets have been synthesized at low temperature (60 °C) through a simple surfactant-free technique. The factors on the formation of the hollowware-like stacked nanosheets have been studied and a possible formation mechanism is proposed. Thermally stable porous Co3O4 with the same morphology was prepared by thermal decomposition of the as-prepared Co(OH)2. The catalytic properties of the porous Co3O4 and Au/Co3O4 are reported.
Co-reporter:Kaka Zhang, Zhou Gui, Daoyong Chen and Ming Jiang
Chemical Communications 2009 (Issue 41) pp:6234-6236
Publication Date(Web):02 Sep 2009
DOI:10.1039/B911574A
Small polymeric nanoparticles sized below 10 nm were effectively synthesized viafree radical polymerization of a cross-linker in a glassy polymer matrix, owing to the successful prohibition of aggregation between the primary nanoparticles by the matrix.
Co-reporter:Jixin Zhu, Zhou Gui
Materials Chemistry and Physics 2009 Volume 118(Issue 1) pp:243-248
Publication Date(Web):15 November 2009
DOI:10.1016/j.matchemphys.2009.07.044
Layered nickel and cobalt hydroxide compounds have been synthesized via a simple hydrothermal growth method and their chemical formulas are established. Labyrinth-like nickel and cobalt oxide porous sheets were prepared using their layered metal hydroxide compounds as precursors by annealed at 500 °C for 3 h, both of them have stable sheet framework and large pores. The factors of the formation of the novel porous structure were investigated and their catalytic properties have been studied.
Co-reporter:Jixin Zhu, Zhou Gui, Yanyan Ding
Materials Letters 2008 Volume 62(Issue 16) pp:2373-2376
Publication Date(Web):15 June 2008
DOI:10.1016/j.matlet.2007.12.002
This letter first describes a facile, low-cost, solution-phase approach to the large-scale preparation of lanthanum hydroxide single crystal nanorods at 60 °C without any template and surfactant. X-ray diffraction (XRD) shows that the nanorods are of pure hexagonal structure. The size and morphology of the products were examined by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Lanthanum hydroxide single crystal nanorods are with diameters of approximately 20 nm and lengths of 150–200 nm. The processes of formation and decomposition for the as-prepared lanthanum hydroxide nanorods were discussed.
Co-reporter:Yanyan Ding, Yuan Hu, Zhou Gui, Lei Song
Materials Letters 2008 Volume 62(Issue 27) pp:4290-4292
Publication Date(Web):31 October 2008
DOI:10.1016/j.matlet.2008.07.005
Poly(methyl methacrylate) (PMMA)/lanthanum hydroxide (La(OH)3) nanowire nanocomposites were prepared by in-situ polymerization of methyl methacrylate (MMA) in the DMF solution. The improvement in thermal stability of the nanocomposites is remarkable with low inorganic nanowires content. The experimental results indicate ultimate network formation for the nanocomposites is possibly through interaction between La3+ and MMA monomer during polymerization. The network induces the mobility restriction of polymer chains and greatly prevents polymer chains from decomposition. The characteristic of one-dimensional nanowires used here may play a key role in the formation of the “cross-link” network and decision of the low content of nanowires addition in the polymer matrix.
Co-reporter:Yanyan Ding, Zhou Gui, Jixin Zhu, Shanshan Yan, Jian Liu, Yuan Hu, Zhengzhou Wang
Materials Letters 2007 Volume 61(11–12) pp:2195-2199
Publication Date(Web):May 2007
DOI:10.1016/j.matlet.2006.08.045
Zinc oxide microtubes were synthesized by hydrothermal method. The cooperation activities of surfactant cetyltrimethylammonium bromide (CTAB) and bidentate ethylenediamine ligand were found to be appropriate for the formation of final tubes. The morphologies and structures of the samples were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). A possible vesicle-template elongating fusion mechanism was proposed and discussed.
Co-reporter:Zhou Gui, Rong Fan, Xianhui Chen, Yuan Hu, Zhengzhou Wang
Materials Research Bulletin 2004 Volume 39(Issue 2) pp:237-241
Publication Date(Web):2 February 2004
DOI:10.1016/j.materresbull.2003.09.035
A novel milk-like Cu–thiourea colloid has been synthesized. Nanocrystalline quaternary copper sulfide Cu2FeSnS4 was obtained through the Cu–thiourea colloidal precursor cooperative conversion route at low temperature. The samples were characterized by means of X-ray powder diffraction, transmission electron microscopy, scanning electron microscopy, inductively coupled plasma atomic emission spectroscopy, and X-ray energy dispersive spectroscopy techniques. The reaction details and features were described and discussed.
Co-reporter:Yanbei Hou, Lijin Duan, Zhou Gui, Yuan Hu
Composites Part A: Applied Science and Manufacturing (June 2017) Volume 97() pp:
Publication Date(Web):June 2017
DOI:10.1016/j.compositesa.2017.02.023
Graphene foams (GFs) with different sizes were prepared and applied to design thermoplastic polyurethane (TPU)/GF nanocomposites by infiltration method. Size-controlled GFs were successfully synthesized with variable concentration of graphene oxide (GO). Stable framework of GFs contributed to uniformity of composites and endowed them preferable thermal and mechanics performance. Results of TGA and MCC manifested that thermostability and flame retardancy of composites were superior to pure polymer, which was contributed to laminar barrier effect of GFs. Compression modulus of composite reached up to 2041.29 kPa, which was much higher than GFs. Due to porous structure, both GFs and TPU/GF composites exhibited quite low value of thermal conductivity. Char residue of TPU/GF composites not only remained original shape, but withstood certain pressure, which decreased potential fire risk. Polymeric materials design, based on GFs, is a feasible scheme to obtain composite with good integrated performance.
Co-reporter:Saihua Jiang, Keqing Zhou, Yongqian Shi, Siuming Lo, Haiyan Xu, Yuan Hu, Zhou Gui
Applied Surface Science (30 January 2014) Volume 290() pp:
Publication Date(Web):30 January 2014
DOI:10.1016/j.apsusc.2013.11.074
•Flower-like BiOCl precursor was prepared by a fast and facile way, and flower-like Bi2S3/BiOCl was synthesized using an in situ TAA etching way.•The flower-like Bi2S3/BiOCl composites possess higher photocatalytic activity compared to single Bi2S3, BiOCl and 2D plate-like Bi2S3/BiOCl composites.•The enhanced photocatalytic activity is due to the heterostructure between Bi2S3 and BiOCl, and large surface area of flower-like structure.Novel BiOCl micro-flower was synthesized by a facile method and used as a precursor to produce Bi2S3/BiOCl composites. The Bi2S3/BiOCl composites, synthesized by in situ etching of BiOCl precursor with thiacetamide (TAA) solution, maintain the hierarchical flower-like structure and exhibit a large surface area. X-ray diffraction (XRD), Fourier transform infrared spectrometry (FT-IR), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDS), and UV–vis diffuse reflectance spectroscopy (DRS) were employed to study the structures, morphologies and optical properties of the as-prepared samples. Under visible light (λ > 400 nm), the flower-like Bi2S3/BiOCl composite displayed much higher photocatalytic activity than single Bi2S3, BiOCl and 2D plate-like Bi2S3/BiOCl composite for the degradation of rhodamine B (RhB). The increased photocatalytic activity of Bi2S3/BiOCl could be attributed to the formation of the heterostructure between Bi2S3 and BiOCl and large surface area of the hierarchical structure, which effectively separate the photoinduced electron–hole pairs and suppress their recombination.
Co-reporter:Yanbei Hou, Weizhao Hu, Zhou Gui, Yuan Hu
Journal of Hazardous Materials (15 July 2017) Volume 334() pp:39-48
Publication Date(Web):15 July 2017
DOI:10.1016/j.jhazmat.2017.03.051
•Cu2O particles were prepared with average particle-size of 10, 100, and 200 nm.•Different-sized Cu2O influenced the combustion behaviors of UPR observably.•Cu2O-S promoted completely combustion of UPR and reduced the gaseous toxicity.•Cu2O-M/Cu2O-L enhanced flame retardancy of UPR.Cuprous oxide (Cu2O) as an effective catalyst has been applied to enhance the fire safety of unsaturated polyester resin (UPR), but the particle size influence on combustion behaviors has not been previously reported. Herein, the UPR/Cu2O composites (metal oxide particles with average particle-size of 10, 100, and 200 nm) were successfully synthesized by thermosetting process. The effects of Cu2O with different sizes on thermostability and combustion behaviors of UPR were characterized by TGA, MCC, TG-IR, FTIR, and SSTF. The results revel that the addition of Cu2O contributes to sufficient decomposition of oxygen-containing compounds, which is beneficial to the release of nontoxic compounds. The smallest-sized Cu2O performs the excellent catalytic decomposition effect and promotes the complete combustion of UPR, which benefits the enhancement of fire safety. While the other additives retard pyrolysis process and yield more char residue, and thus the flame retardancy of UPR composites was improved. Therefore, catalysis plays a major role for smaller-sized particles during thermal decomposition of matrix, while flame retarded effect became gradual distinctly for the larger-sized additives.
Co-reporter:Yongqian Shi, Ze Long, Bin Yu, Keqing Zhou, Zhou Gui, Richard K. K. Yuen and Yuan Hu
Journal of Materials Chemistry A 2015 - vol. 3(Issue 33) pp:NaN17073-17073
Publication Date(Web):2015/07/10
DOI:10.1039/C5TA04349B
Significant improvements in thermal and flame retardant properties of polymeric materials at low loadings hold tremendous promise for fire safety materials. In the present work, a highly effective graphitic carbon nitride/acidized multi-walled carbon nanotube (g-C3N4/aMWCNT) bilayer was deposited on a PS sphere for reducing its fire hazards. The PS sphere allowed the intimate assembly of the g-C3N4/aMWCNT bilayer on its surface through electrostatic interactions. Structural and morphological characterization revealed the successful assembly of PS/g-C3N4/aMWCNT systems. Enhanced thermal stability and flame retardancy (e.g. a decrease of ca. 45% and 47% in HRR and THR, respectively) were obtained for the ternary assembled systems instead of the binary materials. The phenomena were caused by two reasons: g-C3N4/aMWCNT bilayers induced the construction of the “tortuous path” which impeded the permeation of heat and the escape of pyrolysis volatile products; on the other hand, stacked g-C3N4 nanosheets or thermolabile aMWCNTs with an uncompact network structure led to poor thermal stability and fire resistance. Thus, this work paves a potential pathway to design efficient assembled fire-retardant systems for fire safety.
Co-reporter:Yongqian Shi, Keqing Zhou, Bibo Wang, Saihua Jiang, Xiaodong Qian, Zhou Gui, Richard K. K. Yuen and Yuan Hu
Journal of Materials Chemistry A 2014 - vol. 2(Issue 2) pp:NaN544-544
Publication Date(Web):2013/11/01
DOI:10.1039/C3TA13409A
Graphene (Gr)-based binary Gr–CoFe2O4 and Gr–CdS or ternary Gr–CoFe2O4/CdS nanohybrids were prepared via a facile solvothermal strategy. It was encouraging to find that the ternary Gr–CoFe2O4/CdS nanohybrids exhibited the highest photocatalytic degradation ability (80%) among all the photocatalysts. The significant enhancement in photodegradation under 40 W daylight lamp irradiation was attributed to graphene acting as a “bridge”, where electrons generated from CoFe2O4 were transferred to CdS by graphene and finally led to separation of electrons and holes. Interestingly, neat CoFe2O4 resulted in increasing concentration of methylene blue (MB) as the irradiation time increased. The phenomenon was ascribed to adsorption of MB molecules on CoFe2O4 in the dark and desorption from the photocatalyst during irradiation, confirmed by our ingenious experiment. Digital photos of the Gr–CoFe2O4/CdS hybrids in an external magnetic field indicated that the ternary photocatalyst could be easily separated from aqueous solution. The recycle measurements of the photocatalyst revealed that the ternary nanohybrids exhibited acceptable photocatalytic stability due to unstable decoration. This work would provide a new insight into the construction of visible light-responsive and magnetic separable photocatalysts with high performances.
Co-reporter:Kaka Zhang, Zhou Gui, Daoyong Chen and Ming Jiang
Chemical Communications 2009(Issue 41) pp:NaN6236-6236
Publication Date(Web):2009/09/02
DOI:10.1039/B911574A
Small polymeric nanoparticles sized below 10 nm were effectively synthesized viafree radical polymerization of a cross-linker in a glassy polymer matrix, owing to the successful prohibition of aggregation between the primary nanoparticles by the matrix.
![Poly[oxy[(1S)-1-methyl-2-oxo-1,2-ethanediyl]]](http://img.cochemist.com/ccimg/26200/26161-42-2.png)
![Poly[oxy[(1S)-1-methyl-2-oxo-1,2-ethanediyl]]](http://img.cochemist.com/ccimg/26200/26161-42-2_b.png)
