Polymeric carbon nanocomposites from multiwalled carbon nanotubes functionalized with segmented polyurethane

Multiwalled carbon nanotubes (MWNT) were functionalized with segmented polyurethanes (PU) by the “grafting to” approach. Raman and X‐ray photoelectron spectroscopy (XPS) spectra show that the sidewalls of MWNTs have been functionalized with acid treatment, and the amount of COOH increases with increasing acid treatment time. FTIR and X‐ray diffraction (XRD) spectra confirm that PU is covalently attached to the sidewalls of MWNTs by esterification reaction. Similar to the parent PU, the functionalized carbon nanotube samples are soluble in highly polar solvents, such as dimethyl sulfoxide (DMSO) and N,N‐dimethylformamide (DMF). The functionalized acid amount and the grafted PU amount were determined by thermogravimetric analyses (TGA). Comparative studies, based on SEM images between the PU‐functionalized and chemically defunctionalized MWNT samples, also reveal the covalent coating character. Dynamic mechanical analysis (DMA) of nanocomposite films prepared from PU and PU‐functionalized MWNTs show enhanced mechanical properties and increased soft segment T_g. Tensile properties indicate that PU‐functionalized MWNTs are effective reinforcing fillers for the polyurethane matrix. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Mechanical and thermal properties of functionalized multiwalled carbon nanotubes and multiwalled carbon nanotube–polyurethane composites

Multiwalled carbon nanotube (MWNT)–polyurethane (PU) composites were obtained by an in situ polycondensation approach. The effects of the number of functional groups on the dispersion and mechanical properties were investigated. The results showed that the functionalized MWNTs had more advantages for improving the dispersion and stability in water and N,N′‐dimethylformamide. The tensile strength and elongation at break of the composites exhibited obvious increases with the addition of MWNT contents below 1 wt % and then decreases with additions above 1 wt %. The maximum values of the tensile strength and elongation at break increased by 900 and 741%, respectively, at a 1 wt % loading of MWNTs. Differential scanning calorimetry measurements indicated that the addition of MWNTs resulted in an alteration of the glass‐transition temperature of the soft‐segment phase of MWNT–PU. Additionally, new peaks near 54°C were observed with differential scanning calorimetry because of the microphase‐separation structures and alteration of the segment molecular weights of the hard segment and soft segment of PU with the addition of MWNTs. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

水性环氧含硅聚氨酯防腐涂料的研制

以环氧树脂与含硅聚氨酯树脂接枝共聚得到的水性聚氨酯改性环氧丙烯酸树脂为防腐涂料基料,钛铁粉为防腐颜料,制得水性防腐涂料。研究了环氧树脂的用量对涂膜力学性能的影响。探讨了不同防腐颜料及其用量、不同基料树脂对涂料防腐性能的影响。结果表明,当环氧树脂E-44的用量占树脂质量的30%,以钛铁粉为防腐颜料且其用量为5%时,所合成的防腐涂料的综合性能最优。     

Hydrogen bond containing multiwalled carbon nanotubes in polyurethane composites

Introduction of hydrogen bonding sites onto multi‐walled carbon nanotubes (MWCNTs) included carboxylic acid, amide‐amine, and novel amide‐urea MWCNTs for the formation of homogenous polyurethane composites. Acid oxidation and subsequent derivatization introduced hydrogen bonding functionality onto MWCNTs to reveal the effect of surface functionalization on mechanical properties in a 45 wt% hard segment polyurethane matrix. Raman spectroscopy showed an increase in the D/G peak ratio, which indicated successful oxidation, and X‐ray photoelectron spectroscopy also revealed elemental compositions that supported each step of the functionalization strategy. Thermogravimetric analysis supported functionalization with an increase in percent weight loss for each functionalization, and the MWCNT surface functionalization determined pH‐dependent dispersibility. The nonfunctionalized MWCNT composites showed poor dispersion with transmission electron microscopy, and in sharp contrast, the functionalized composites displayed homogenous dispersions. Tensile testing revealed improved stress at break in the functionalized MWCNT composites at low loadings due to homogenous dispersion. POLYM. COMPOS., 37:1425–1434, 2016. © 2014 Society of Plastics Engineers     

Thermal stability and molecular interaction of polyurethane nanocomposites prepared by in situ polymerization with functionalized multiwalled carbon nanotubes

Polyurethane (PU) nanocomposites were prepared through conventional and in situ methods with multiwalled carbon nanotubes (MWNTs) functionalized with poly(ϵ-caprolactone). The thermal degradation and stability of PU–MWNT nanocomposites were investigated with nonisothermal thermogravimetry and were explained in terms of the interaction between MWNTs and PU molecules with Fourier transform infrared spectroscopy. The difference in thermal stability between the conventional and in situ nanocomposites was also compared. The thermal degradation of all the nanocomposite samples took place in two stages and followed a first-order reaction. The degradation temperature of the in situ nanocomposites was higher than that of the conventional nanocomposites with the same loading of MWNTs. The activation energy at 10% degradation and the half-life period were also higher in the in situ nanocomposites compared to the conventional nanocomposites. Such higher thermal stability of the in situ nanocomposites was ascribed to covalent bond formation between MWNTs and PU chains, which could result in better dispersion of MWNTs in the PU matrix for the in situ nanocomposites than for the conventional nanocomposites. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Improved corrosion resistance based on APTES-grafted reduced sulfonated graphene/waterborne polyurethane coatings

In this work, reduced sulfonated graphene (RSG) containing free amine groups was prepared and modified by 3-aminopropyltriethoxysilane (APTES) and reduction by diethanolamine (DEA). In addition, waterborne polyurethane (WPU) composite coatings were prepared by adding RSG as an anticorrosive filler to WPU. From the results of Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy (SEM), it can be found that sulfonated graphene was modified with APTES and successfully reduced by DEA. The SEM images illustrated that RSG was uniformly doped in the WPU. With increasing RSG content, the hydrophobicity of the RSG/WPU films increased due to the strong covalent interaction between RSG and WPU. Finally, the corrosion resistance of the coating was characterized by polarization curves and salt spray tests.     

Protein adsorption on functionalized multiwalled carbon nanotubes with amino‐cyclodextrin

A novel amino‐cyclodextrin was synthesized, and it was covalently attached to multiwalled carbon nanotubes (MWNTs). The functionalized MWNTs (f‐MWNTs) have very good aqueous dispersibility. Bovine serum albumin (BSA) was adsorbed onto f‐MWNTs through noncovalent interactions, including the hydrophobic interaction of the residues of BSA with the wall of MWNT and the guest–host interaction of the residues with the cyclodextrin (CD) moieties of f‐MWNTs. The ultraviolet–visible (UV–vis) absorption of the f‐MWNT‐BSA hybrid was measured with UV–vis spectrometer, and the absorbance can be described well with the Beer–Lambert law. The X‐ray diffraction patterns have indicated that the crystalline form of BSA has been changed after the adsorption of BSA on f‐MWNTs. The circular dichroism spectra have shown that a high percentage of α‐helical content can be retained for BSA adsorbed on f‐MWNTs. The results also indicate that the change of secondary structure of BSA is mainly due to the hydrophobic interaction of the residues of BSA with the wall of f‐MWNT, whereas the secondary structure is much less affected by the interaction of the CD moieties with BSA. © 2011 American Institute of Chemical Engineers AIChE J, 2011     

Preparation and characterization of nylon610/functionalized multiwalled carbon nanotubes composites

Nylon610 nanocomposites containing functionalized multiwalled carbon nanotubes (MWCNTs) were prepared using wet melt blending method, which is a novel preparation technique. In comparison with the pure nylon610, the elastic modulus, tensile strength, bending modulus, and bending strength of the composites increase significantly with the increase of MWCNTs content, and the mechanical properties of the composites are also improved significantly by adding a small amount of MWCNTs (0.1 wt %). The crystallization peak of the composites shifts to higher temperature with the addition of MWCNTs, and among the two melting peaks, the intensity of melting peak at low temperature decreases with increasing MWCNTs content. The composites are more stable than pure PA610 and decompose at higher temperature, suggesting that the accession of MWCNTs can improve the composites' thermal stability. The storage modulus of the composites decreases with the temperature increasing, but under lower temperature it increases significantly with the addition of MWCNTs–COOH except for PANT‐0.1 sample. Transmission electron microscope (TEM) images of composites exhibit that the wet melt blending technique can avoid the excess agglomeration of MWCNTs under vacuum dryness, which benefits MWCNTs to disperse uniformly in matrix. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Fabrication of multiwalled carbon nanotube-reinforced rapeseed-oil-based polyurethane coatings for anticorrosive applications

This work describes the synthesis of a hydroxy-terminated oligomer for polyurethane preparation (HTO-PU) from rapeseed oil, salicylic acid and toluene diisocyanate. HTO-PU was further incorporated with different amounts of multiwalled carbon nanotubes (MWCNTs) to produce HTO-PU@MWCNT nanocomposites. These nanocomposites were then converted to coatings using mild steel strip as a substrate and allowed to cure at room temperature. Fourier transform infrared and NMR spectroscopic techniques were used for structural elucidation. Surface morphology was determined using scanning electron microscopy and X-ray photoelectron spectroscopy. Thermal stability (>300 °C) of these coatings was evaluated through thermogravimetric analysis and differential scanning calorimetry. Contact angle values suggest that incorporation of MWCNTs enhanced the hydrophobicity of HTO-PU coatings. Physicomechanical results reveal that these coatings are highly glossy, scratch resistant and impact resistant possessing good adhesion and excellent pencil hardness. The optimum concentration of MWCNTs was found to be 1.0 wt. %, below and above which the coating performance was observed to deteriorate. The corrosion resistance and barrier properties of these coatings were examined using electrochemical impedance spectroscopy, the results of which suggest excellent corrosion inhibition efficiency of HTO-PU@MWCNT-1.0 coatings until 28 days. This study suggests a step towards synthesis of MWCNT-incorporated green PU coatings for protective applications. © 2022 Society of Industrial Chemistry.     

水性聚氨酯/环糊精修饰多壁碳纳米管复合材料的制备与性能

为改善多壁碳纳米管(MWNTs)的水分散性,将其与β-环糊精(CD)研磨以及超声分散,得到环糊精修饰碳纳米管(CDMWNTs),并通过与水性聚氨酯球磨共混,制备了水性聚氨酯/CD修饰碳纳米管复合乳液,其固化成膜后利用热重分析、万能材料试验机、扫描电镜和绝缘电阻测试仪探讨了CDMWNTs含量对复合胶膜热稳定性、力学性能、微观形貌和导电性的影响。通过粒径分析与红外光谱说明了CD改性处理对MWNTs的影响。结果显示,与纯聚氨酯胶膜相比,当CDMWNTs加入量为3.0%时,复合胶膜的拉伸强度和断裂伸长率分别提高了72.29%和17.22%;其电阻率为174?·m,减小了5个数量级,显著提高了聚氨酯的导电性;其热稳定性也得到一定的提高。相同加入量下,CDMWNTs所制复合胶膜的性能好于未改性MWNTs所制复合胶膜的性能。     

High-density attachment of gold nanoparticles on functionalized multiwalled carbon nanotubes using ion exchange

The attachment of gold nanoparticles (NPs) onto chemically functionalized multiwalled carbon nanotubes (MWCNTs) by ion pairing interaction is reported. The structure and composition of the resulting gold NP/MWCNT hybrids were characterized by transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. A high-density of gold NPs was homogeneously dispersed on the modified MWCNTs. The hybrids show characteristic plasmon absorption of gold NPs in the UV-visible spectrum and good electrochemical properties.     

Effect of 3-Aminopropyltriethoxysilane on polycarbonate based waterborne polyurethane transparent coatings

A series of waterborne polyurethane (WPU) dispersions modified with different contents of 3-aminopropyltriethoxysilane (APTES) were synthesized based on poly(1,6-hexyl 1,2-ethylcarbonate) diol (PHEC) and isophorone diisocyanate (IPDI), and the films were obtained by casting the dispersions on Teflon molds. Effects of APTES content on the particle size and viscosity of the dispersions were studied. The structure and properties of the resulting films were investigated by Fourier transform infrared spectroscopy, wide angle X-ray diffraction measurement, dynamic mechanical analysis, thermogravimetric analysis and mechanical testing. The experimental results showed that the incorporation of APTES played an important role in the enhancement of the water and toluene resistance and mechanical properties of the SPU films. Young's moduli and ultimate tensile strengths were improved from 8.0 to 451 MPa and 6.5–19 MPa respectively as the APTES content increased from 1 wt.% to 20 wt.%. The ability of scratch resistance was enhanced, when the content of APTES increased to 20 wt.%, the 3H pencil could not mar the surface. Moreover, the transmittance spectra indicated that the coatings showed high transparence.     

Effect of natural and synthetic surface coatings on the toxicity of multiwalled carbon nanotubes toward green algae

Ubiquitous dissolved organic matter (DOM) from various sources can interact with discharged multiwalled carbon nanotubes (MWCNTs) and pose distinct effects on the toxicity of MWCNTs to aquatic organisms. This study for the first time compared effects of a natural originated humic acid (HA) and two synthetic surfactants (sodium dodecylbenzenesulfonate – SDBS, octyl phenoxy polyethoxyethanol – TX100) on the toxicity of MWCNTs to a unicellular green alga (Chlorella pyrenoidosa). Algal growth inhibition, cell surface hydrophobicity, oxidative stress, MWCNT-cell agglomeration, and cell morphology change and internalization of MWCNTs were assayed to investigate individual and combined toxicities of MWCNTs and DOMs, and mechanisms underlying different effects of DOMs on the toxicity of MWCNTs were specifically addressed. It is shown that SDBS and TX100 were capable of promoting cell internalization of MWCNTs and triggering higher oxidative stress, and thereby increasing the toxicity of MWCNTs; while HA could alleviate the toxicity of MWCNTs through limiting cell internalization of MWCNTs and reducing oxidative stress. The outcomes of this work shed new light on the assessment of ecological toxicity of discharged nanomaterials.     

Fabrication of active corrosion protection waterborne polyurethane coatings using cerium modified palygorskite nanocontainers

The development of eco-efficient and environmental friendly active anti-corrosion coatings for metallic substrates represents a fundamental milestone in many engineering applications. Herein, a new type of active corrosion protection coating was successfully synthesized simply based on waterborne polyurethane (WPU) and nanocontainer of Ce³⁺ modified palygorskite (Ce-PAL). Particularly, the nanocontainer of Ce-PAL was achieved via a facile and green process by cation exchange in water. Inductively coupled plasma atomic emission spectrometry (ICP) revealed that Ce³⁺ had successfully incorporated into PAL nanofibers with a loading amount of 10.334 g/kg. The salt immersion test, electrochemical potentiodynamic measurements and electrochemical impedance spectroscopy (EIS) demonstrated that the incorporation of Ce-PAL only with 2 wt% into WPU led to a significant improvement of their corrosion protection properties. Finally, according to the results of scanning electron microscopy with energy dispersive X-ray spectroscopy, the active anti-corrosion mechanism of Ce-PAL/WPU coating was proposed.     

水性聚氨酯涂料的功能化及性能

综述了近年水性聚氨酯涂料功能化及性能的最新研究进展,主要包括阻燃型水性聚氨酯涂料、防腐型水性聚氨酯涂料、防水型水性聚氨酯涂料、防霉型水性聚氨酯涂料以及其它功能化水性聚氨酯涂料,并对功能化水性聚氨酯涂料未来的发展趋势进行了阐述和总结。研制具有自修复功能和可生物降解的新型水性聚氨酯涂料以及开发具有较高性价比的水性聚氨酯涂料功能化的新技术和新工艺将是该领域今后的主要目标。     

Synthesis and characterization of multiwalled carbon nanotube/polyurethane composites via surface modification multiwalled carbon nanotubes using silane coupling agent

Well‐dispersed multiwalled carbon nanotubes/polyurethane (MWCNTs/PU) composites were synthesized in situ polymerization based on treating MWCNTs with nitric acid and silane coupling agent. The morphology and degree of dispersion of the MWCNTs were studied using a high resolution transmission electron microscopy (HR‐TEM) and X‐ray powder diffraction (XRD). The result showed that MWCNTs could be dispersed still in the PU matrix well with the addition of 2 wt% MWCNTs. The thermal and mechanical properties of the composites were characterized by dynamic mechanical thermal analysis, thermogravimetric analysis, tensile, and impact testing. The result suggested that the glass transition temperature (T_g) of composites increased greatly with increasing MWCNTs content slightly, and the MWCNTs is also helpful to improve mechanical properties of composites. Furthermore, the composites have an excellent mechanical property with the addition of 0.5 wt% MWCNTs. The electrical property testing indicates that the MWCNTs can improve evidently the electrical properties of composites when adding 1 wt% MWCNTs to the PU matrix. The volume resistivity of composites reaches to an equilibrium value. POLYM. COMPOS., 33:1866–1873, 2012. © 2012 Society of Plastics Engineers     

水性聚氨酯涂料催化剂研究进展

随着环保意识的逐渐加强,水性聚氨酯涂料越来越受到重视.催化剂是水性聚氨酯涂料的重要组成部分.本文综述了水性聚氨酯催化剂(包括胺类催化剂、金属有机化合物类催化剂和复合催化剂等)的研究状况.     

水性聚氨酯树脂在工业水性涂料中的应用进展

综述了工业用水性聚氨酯涂料的主要应用领域。主要介绍了水性聚氨酯涂料目前改性研究的现状,如防腐防锈涂料、防水涂料、防火涂料、抗外力涂料、防污涂料、新型智能化涂料等改性研究。最后,根据我国国情,阐述了水性聚氨酯涂料未来的发展方向。