硅丙乳液包覆Mg(OH)2核壳结构纳米粒子的制备与表征

为有效提高Mg(OH)_2纳米粒子在硅丙乳液中的相容性与分散稳定性,在油酸修饰Mg(OH)_2纳米粒子的基础上,以甲基丙烯酸甲酯、丙烯酸丁酯、丙烯酸与乙烯基三乙氧基硅烷为共聚单体,通过乳液聚合法制备出具有核壳结构的硅丙乳液包覆Mg(OH)_2复合材料。利用傅里叶变换红外光谱仪(FTIR)、X射线衍射仪(XRD)、透射电子显微镜(TEM)等测试手段对样品结构、形貌进行了表征。通过燃烧实验,研究了硅丙乳液包覆Mg(OH)_2纳米粒子对水性防火涂料阻燃性能的影响。结果表明,油酸通过酯化作用修饰在Mg(OH)_2纳米粒子表面,借助油酸分子中双键结构,丙烯酸类混合单体在纳米Mg(OH)_2表面完成聚合过程,形成以Mg(OH)_2纳米粒子为核、硅丙乳液为壳的复合材料。XRD与热分析表明经硅丙乳液包覆的纳米Mg(OH)_2晶体结构与热稳定性能未受影响。此外,掺杂0.1%(质量分数)的硅丙乳液包覆Mg(OH)_2可使水性防火涂料阻燃时间延长至113 min,较未掺杂水性涂料阻燃时间(91min)提高约23%。     

Synthesis and properties of polystyrene/Fe-montmorillonite nanocomposites using synthetic Fe-montmorillonite by bulk polymerization

Fe-montmorillonite (Fe-MMT) was hydrothermally synthesized. It was modified by cetyl trimethylammonium bromide (CTAB) and successfully synthesized polystyrene/Fe-montmorillonite (PS/Fe-MMT) nanocomposites via bulk polymerization for the first time. The resulting nanocomposites were characterized by X-ray diffraction (XRD) spectra, transmission electron microscopy (TEM), high resolution electronic microscopy (HREM), thermal gravimetric analysis (TGA) and cone calorimeter. XRD, TEM and HREM indicated that both intercalated and exfoliated-intercalated structures were observed. In comparison with pure PS, the thermal stability was notably improved in the presence of clay. From cone calorimetry it was found that the peak of heat release rate (HRR) was significantly reduced by the formation of the nanocomposites. Also intercalated nanocomposites were more effective than exfoliated-intercalated nanocomposites in fire retardancy.     

PMB/GO纳米复合材料的制备及阻燃性能

用共混法制备甲基丙烯酸甲酯-丙烯酸丁酯共聚物(PMB)/氧化石墨(GO)纳米复合材料。采用X射线衍射(XRD)和透射电镜(TEM)对复合材料结构进行了表征,并采用热重分析法(TGA)和锥形量热分析(CONE)研究了其阻燃性能变化。XRD和TEM分析结果表明,复合物中添加GO形成剥离型结构的纳米复合材料。TGA研究发现复合材料的热稳定性得到提高。CONE的测试结果表明,GO极大地改善了体系的燃烧性能,其中加5%GO体系的pk-HRR降低了62.2%。     

Preparation of poly(vinyl alcohol)/kaolinite nanocomposites via in situ polymerization

Poly(vinyl alcohol)/kaolinite intercalated nanocomposites (Kao-PVA) were prepared via in situ intercalation radical polymerization. Vinyl acetate (VAc) was intercalated into kaolinite by a displacement method using dimethyl sulfoxide/kaolinite (Kao-DMSO) as the intermediate. Then, PVAc/kaolinite (Kao-PVAc) was obtained via radical polymerization with benzoyl peroxide (BPO) as initiator. Last, PVAc/kaolinite was saponified via direct-hydrolysis with NaOH solution in order to obtain PVA/kaolinite nanocomposites, which was characterized by Fourier-Transformation spectroscopy (FTIR), wide X-ray diffraction (WXRD) and transmission electron microscopy (TEM). Their differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) results of the obtained PVA/kaolinite suggested that the thermal properties had an obvious improvement.     

Nanodiamond/poly (lactic acid) nanocomposites: Effect of nanodiamond on structure and properties of poly (lactic acid)

Nanodiamond (ND)/poly (lactic acid) (PLA) nanocomposites with potential for biological and biomedical applications were prepared by using melting compound methods. By means of transmission electron microscopy (TEM), Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Thermogravimetric analyses (TGA), Dynamic mechanical analyses (DMA), Differential scanning calorimetry (DSC) and Tensile test, the ND/PLA nanocomposites were investigated, and thus the effect of ND on the structural, thermal and mechanical properties of polymer matrix was demonstrated for the first time. Experimental results showed that the mechanical properties and thermal stability of PLA matrix were significantly improved, as ND was incorporated into the PLA matrix. For example, the storage modulus (E′) of 3 wt% ND/PLA nanocomposites was 0.7 GPa at 130 °C which was 75% higher than that of neat PLA, and the initial thermal decomposition was delayed 10.1 °C for 1 wt% ND/PLA nanocomposites compared with the neat PLA. These improvements could be ascribed to the outstanding physical properties of ND, homogeneous dispersion of ND nanoclusters, unique ND bridge morphology and good adhesion between PLA matrix and ND in the ND/PLA nanocomposites.     

Preparation,structure and thermal properties of polylactide/sepiolite nanocomposites with and without organic modifiers

Polylactide-based nanocomposites containing unmodified and organic modified sepiolite were prepared through a solution casting method. The structure and properties of materials were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). From the results it can be concluded that the bundles of sepiolite have been dispersed into small aggregates containing several nanorods without destroying the crystal structure. Sepiolite nanofibers were well dispersed in the PLA matrix, exhibiting a randomly orientation with the contact among them in all cases. But the thermal stability of nanocomposites has been improved more by introducing unmodified sepiolite than that with organic modified sepiolite, which has also been confirmed by molecular dynamics simulation results that hydrophobic parts of organic modifiers could prevent the interaction between PLA molecules and sepiolite surface.     

Direct synthesis of PbS/polypyrrole core-shell nanocomposites based on octahedral PbS nanocrystals colloid

PbS/polypyrrole core-shell nanocomposites were successfully synthesized via in situ chemical oxidation polymerization of pyrrole based on the octahedral PbS nanocrystals colloid. Transmission electron microscopy (TEM) showed that the PbS nanocrystals are as the cores of the nanocomposites and the polypyrrole wrap the octahedral PbS nanocrystals as the shell. X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectra and UV-Vis spectra were used to characterize the structure of the obtained PbS/polypyrrole nanocomposites. A possible formation mechanism of the PbS/polypyrrole core-shell nanocomposites was also proposed.     

Synthesis and properties of waterborne polyurethane/attapulgite nanocomposites

The novel nanocomposites derived from waterborne polyurethane (WPU)/Attapulgite (AT) nanocomposites have been successfully synthesized by in situ polymerization progress. AT functionalized by chemical modification were incorporated as a crosslinker in prepolymer. The chemical structures, morphology, thermal behavior, and mechanical properties of the WPU/AT nanocomposites were investigated by Fourier transform infrared spectroscopy (FTIR), thermo gravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), X-ray diffraction (XRD) and tensile testing respectively. The experimental results indicated that the organically modified attapulgites were homogeneously dispersed in the WPU and resulted in an improvement of thermal stability, tensile strength and elongation at break of WPU/AT nanocomposites.     

CeO2/聚苯胺纳米复合材料的合成与表征

合成了具有核-壳结构的CeO2/聚苯胺纳米复合材料,并用傅立叶变换红外光谱仪(FTIR)、X射线衍射仪(XRD)、透射电子显微镜(TEM)和热分析仪(TG)等对样品的成分、结构、粒度和稳定性进行了表征.结果表明:该纳米复合材料具有核-壳结构,其核平均粒径为17nm,且热稳定性高.     

Polyacrolein/mesoporous silica nanocomposite: Synthesis,thermal stability and covalent lipase immobilization

In this work, new polyacrolein/MCM-41 nanocomposites with good phase mixing behavior were prepared through an emulsion polymerization technique. Mesoporous silica was synthesized by in situ assembly of tetraethyl orthosilicate (TEOS) and cetyl trimethyl ammonium bromide (CTAB). The structure and properties of polyacrolein containing nanosized MCM-41 particle (5 and 10 wt%), were investigated by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, Dynamic light scattering (DLS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N₂ adsorption techniques, and thermogravimetric (TGA) analyses. The SEM images from the final powder have revealed good dispersion of the MCM-41 nanoparticles throughout polymeric matrix with no distinct voids between two phases. The results indicated that the thermal properties of the nanocomposite were enhanced by addition of MCM-41. Thermomyces lanuginosa lipase (TLL) was used as a model biocatalyst and successfully immobilized with polyacrolein and the nanocomposite via covalent bonds with the aldehyde groups. The activity between free enzyme, polyacrolein, and MCM-41 nanocomposite (10 wt%)-immobilized TLL was compared. The immobilized lipase with the nanocomposite shows better operational stability such as pH tolerance, thermal and storage stability. In addition, the immobilized lipase with the nanocomposite can be easily recovered and retained at 74% of its initial activity after 15 time reuses.     

Nickel oxide/polypyrrole/silver nanocomposites with core/shell/shell structure: Synthesis,characterization and their electrochemical behaviour with antimicrobial activities

Magnetic and conducting Nickel oxide–polypyrrole (NiO/PPy) nanoparticles with core–shell structure were prepared in the presence of Nickel oxide (NiO) in aqueous solution containing sodium dodecyl benzenesulfonate (SDBS) as a surfactant as well as dopant. A stable dispersion of silver (Ag) nanoparticles was synthesized by chemical (citrate reduction) method. NiO/PPy nanocomposites were added to the Ag colloid under stirring. Ag nanoparticles could be electrostatically attracted on the surface of NiO/PPy nanocomposites, leading to formation of NiO/PPy/Ag nanocomposites with core/shell/shell structure. The morphology, structure, particle size and composition of the products were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, cyclic voltammetry (CV) and current–voltage (I–V) analysis. The resultant nanocomposites have the good conductivity and excellent electrochemical and catalytic properties of PPy and Ag nanoparticles. Furthermore, the nanocomposites showed excellent antibacterial behaviour due to the presence of Ag nanoparticles in the composite. The thermal stability of NiO–PPy as well as NiO/PPy/Ag nanocomposites was higher than that of pristine PPy. Studies of IR spectra suggest that the increased thermal stability may be due to interactions between NiO and Ag nanoparticles with the PPy backbone.     

Preparation of polymer nanocomposites of core-shell structure via surface-initiated atom transfer radical polymerizations

Polymer nanocomposites of core-shell structure were prepared by grafting poly(tert-butyl acrylate) (Pt-BA) from SiO₂ nanoparticle via the surface-initiated polymerization (SIP) strategy. This new organic inorganic hybrid particle has been extensively characterized by XPS (X-ray Photoelectron Spectroscopy), SEM (Scanning Electron Microscopy), TEM (Transmission Electron Microscopy), and TGA (ThermoGravimetric Analysis).     

Magnesium hydroxide sulfate hydrate whisker flame retardant polyethylene/montmorillonite nanocomposites

Flame retardant maleated polyethylene/magnesium hydroxide sulfate hydrate whisker (MAPE/MHSH) composites containing organo-modified montmorillonite (OMT) were prepared by direct melt intercalation. Their morphology, combustion behaviour and thermal stability were carried out by X-ray diffraction (XRD), transmission electron microscopy (TEM), cone calorimetry and thermogravimetric analyses (TGA). The exfoliation of silicate layers within MAPE has been verified by XRD and TEM images. Cone calorimetry results indicated that a synergistic flame retardant effect on reducing heat release rate (HRR) occurred when MHSH and OMT were both present in nanocomposite. The reduction in HRR improved as the mass fraction of OMT was increased from 2 to 10 wt%, but there was little improvement above 5 wt% OMT loading level. TGA profiles of the nanocomposites revealed that the thermodegradation stability of the nanocomposites decreased as the OMT fraction increased from 2 to 10 wt%.     

Synthesis and characterization of thermoplastic polyurethane/montmorillonite nanocomposites produced by reactive extrusion

The novel polyurethane/montmorillonite (PU/MMT) nanocomposites based on poly (propylene oxide) glycol (POP), 4,4′-diphenymethylate diisocyanate (MDI), 1,4-butanediol (1,4-BD) and MMT has been synthesized using a one-step direct polymerization-intercalation technique by twin-screw extruder. Its structure and thermal properties are characterized by X-ray diffraction (XRD), Transmission electron microscopy (TEM) and High-resolution electron microscopy (HREM), Fourier-transform infrared spectroscopy (FTIR) and Thermogravimetry analysis (TGA), respectively. The results of XRD and HREM analyses show that the silicate layer is well dispersed in PU matrix and this mesostructure can be considered as a delaminated nanocomposites. The TGA analysis indicates that the thermal stability properties of the PU/MMT nanocomposites are increased slightly compared with the pristine PU, due to the increase of the char residue. The mechanical and flammability performances are examined by electronic Universal Tester and Cone calorimetry, respectively. The layered silicate, which acts as a high aspect ratio reinforcement, enhances tensile strength of the PU. Specifically, there is a 25% increase in the tensile strength of PU nanocomposites containing 4 wt.% MMT compared with that of pristine PU. However, the elongation at break of PU/MMT nanocomposites is lower than that of pristine PU. The loading of MMT leads to the remarkably decrease of heat release rate (HRR), contributing to the improvement of flammability performance.     

聚苯乙烯/银核壳结构纳米微球的制备与表征

采用两步法的简单路线制备出银纳米粒子包覆的聚苯乙烯(PS)微球,首先通过乳液聚合法合成出聚苯乙烯微球;然后对苯乙烯进行敏化和活化,搅拌下加入银的还原液,从而制备出Ag-PS核壳结构的纳米微球.同时借助于TEM、UV-vis、 FE-SEM进行表征,分析其微观结构.结果表明,所得的聚苯乙烯微球粒径约为40nm;聚苯乙烯/银核壳结构纳米微球粒径为45～350nm,银层厚度可随意调控.     

Poly(butylene terephthalate)/organoclay nanocomposites prepared by in-situ bulk polymerization with cyclic poly(butylene terephthalate)

The PBT/organoclay nanocomposites were prepared with cyclic poly(butylene terephthalate) oligomers and organically modified clay via in-situ bulk polymerization. Dispersion of the clay layers in the PBT nanocomposites was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The thermal stability of the nanocomposites was studied by thermal gravimetric analyses (TGA). These results indicate that organoclay has been dispersed homogeneously in the PBT matrix, and the nanocomposites with intercalated-exfoliated structure were synthesized via this method. The onset degradation temperature of the nanocomposites was increased by 8-10 °C compared with the PBT homopolymer without any clay.     

溶液插层法制备PPC/OMMT纳米复合材料及性能表征

通过溶液插层法制备了聚甲基乙撑碳酸酯/有机蒙脱土(PPC/OMMT)纳米复合材料,采用X射线衍射仪、热失重分析仪、透射电子显微镜(TEM)、动态力学性能测试仪(DMA)等对PPC/OMMT的性能进行了表征.XRD和TEM测试表明,OMMT均匀分散于PPC基体中并形成了插层型的纳米复合结构;DMA分析结果表明,复合材料的...     

Improved thermal stability of poly(vinyl chloride) by nanoscale layered double hydroxide particles grafted with toluene-2,4-di-isocyanate

A novel interlamellar surface modification of layered double hydroxides (LDHs) via covalent bonding by toluene-2,4-di-isocyanate (TDI) has been successfully obtained, and poly(vinyl chloride) (PVC)/TDI-modified LDH nanocomposites have been prepared via solution intercalation process. After the interlamellar modification, TDI was grafted to the surface hydroxyl groups of LDHs with nitrate, dodecyl sulfate or stearate anion as counterion anion. The structures of the TDI-modified LDHs and the nanocomposites were characterized by powder X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectra, and transmission electron microscopy (TEM) techniques. The enhanced thermal stability of PVC/TDI-modified LDH nanocomposites was confirmed by means of conventional Congo Red test and dynamic thermogravimetric analysis (TGA). In addition, the thermal degradation mechanism was briefly discussed on the basis of the above experimental results.     

Hybrid S-valine functionalized multi-walled carbon nanotubes/poly(amid-imide) nanocomposites containing trimellitimidobenzene and 4-hydroxyphenyl benzamide moieties: preparation,processing, and thermal properties

In this paper, amino acid functionalized multi-walled carbon nanotubes (f-MWCNTs)/poly(amide-imide) (PAI) nanocomposites (NCs) were prepared by a solution mixing method. First, 4,4′-methylenebis(3-chloro-2,6-diethyl trimellitimidobenzene) reacted with 3,5-diamino-N-(4-hydroxyphenyl)benzamide in tetra-n-butylammonium bromide as a green medium and a safe methodology (toxic and volatile organic solvents were eliminated) to produce a nanostructured PAI in high yield. MWCNTs were chemically modified with S-valine using microwave irradiation in order to obtain a homogeneous dispersion of MWCNTs in the PAI matrix. The resulting NCs were also characterized by FT-IR, powder X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and thermogravimetric analysis. The TEM and FE-SEM images confirmed good dispersion of f-MWCNTs in the polymer matrix. The results of TGA analysis suggest that a good thermal stability occurs especially with low filler amounts (5 wt%) of f-MWCNT.     

Preparation,microstructure and thermal mechanical properties of epoxy/crude clay nanocomposites

To improve the performance/cost ratio of epoxy/clay nanocomposites, epoxy resin was reinforced with crude clay with the help of a silane modifier. The epoxy/crude clay nanocomposites were produced through a recently developed “slurry compounding” approach. The microstructure of the nanocomposites was characterized with X-ray diffraction (XRD), optical microscopy and transmission electron microscopy (TEM). The thermal mechanical properties were studied with dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA). It has been shown that only 5 wt% of silane modifier is required to facilitate the dispersion and exfoliation of crude clay in epoxy matrix. The storage moduli and thermal stability were improved with the addition of crude clay.