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Electrochemical Application and AFM Characterization of Nanocomposites: Focus on Interphase Properties
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. Shandong University.
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The use of graphene and conductive polyaniline nanomaterials in the field of electrochemistry is increasing due to their excellent conductivity, rapid electron transfer and high specific surface area. However, these properties are strongly dependent on the preparation processes. To accelerate the development of advanced electrochemical sensors for the simultaneous detection of trace amounts of heavy metal ions, two facile and green methods are proposed to improve their performance in this thesis. The first one was dedicated to make graphene-carbon nanotube hybrid nanocomposites. The introduction of carbon nanotubes not only greatly enhances the conductivity of graphene but also suppresses, to some degree, the aggregation between graphene nanosheets. Another method proposed in this thesis work was to synthesize a phytic acid doped polyaniline nanofiber based nanocomposite. The synergistic contribution from polyaniline nanofibers and phytic acid enhances the accumulation efficiency and the charge transfer rate of metal ions during the differential pulse anodic stripping voltammetry analysis. The above-mentioned nanocomposite modified electrodes were all successfully applied to real samples for the simultaneous detection of Cd2+ and Pb2+ with good recovery rates. Meanwhile, corrosion protection is another important branch in the field of electrochemistry. In this direction, an active alkyd-polyaniline composite coating with self-healing functionality was prepared. The polyaniline used in this thesis was doped with p-toluene sulfonic acid, which was employed to increase the conductivity of polyaniline, and 1 wt.% of as-prepared polyaniline nanoparticles were found to offer an effective conductive network for anticorrosion. Finally, the reasons that such low loading levels of nanomaterials can result in significantly reinforced properties in nanocomposites were studied with combined atomic force microscopy (AFM) techniques. The results demonstrated that the interphase for a 40-nm-sized silica particle could extend to 55–70 nm in poly(ethyl methacrylate) (PEMA) and poly(isobutyl methacrylate) (PiBMA) polymer matrix, and the interphase exhibited a gradient distribution in surface nanomechanical properties.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2017. , p. 72
Series
TRITA-CHE-Report, ISSN 1654-1081 ; 2017:13
Keyword [en]
Electrochemical sensor, nanocomposite, graphene, carbon nanotubes, phytic acid, polyaniline, corrosion protection, silica nanoparticles, atomic force microscopy, interphase
National Category
Materials Chemistry
Research subject
Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-203239ISBN: 978-91-7729-285-2 (print)OAI: oai:DiVA.org:kth-203239DiVA, id: diva2:1081716
Public defence
2017-03-10, F3, Lindstedtsvägen 26, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20170315

Available from: 2017-03-15 Created: 2017-03-14 Last updated: 2017-03-17Bibliographically approved
List of papers
1. Ultrasensitive and simultaneous detection of heavy metal ions based on three-dimensional graphene-carbon nanotubes hybrid electrode materials
Open this publication in new window or tab >>Ultrasensitive and simultaneous detection of heavy metal ions based on three-dimensional graphene-carbon nanotubes hybrid electrode materials
2014 (English)In: Analytica Chimica Acta, ISSN 0003-2670, E-ISSN 1873-4324, Vol. 852, p. 45-54Article in journal (Refereed) Published
Abstract [en]

A green and facile method was developed to prepare a novel hybrid nanocomposite that consisted of one-dimensional multi-walled carbon nanotubes (MWCNTs) and two-dimensional graphene oxide (GO) sheets. The as-prepared three-dimensional GO-MWCNTs hybrid nanocomposites exhibit excellent water-solubility owing to the high hydrophilicity of GO components; meanwhile, a certain amount of MWCNTs loaded on the surface of GO sheets through p-p interaction seem to be "dissolved" in water. Moreover, the graphene(G)-MWCNTs nanocomposites with excellent conductivity were obtained conveniently by the direct electrochemical reduction of GO-MWCNTs nanocomposites. Seeing that there is a good synergistic effect between MWCNTs and graphene components in enhancing preconcentration efficiency of metal ions and accelerating electron transfer rate at G-MWCNTs/electrolyte interface, the G-MWCNTs nanocomposites possess fast, simultaneous and sensitive detection performance for trace amounts of heavy metal ions. The electrochemical results demonstrate that the G-MWCNTs nanocomposites can act as a kind of practical sensing material to simultaneously determine Pb2+ and Cd2+ ions in terms of anodic stripping voltammetry (ASV). The linear calibration plots for Pb2+ and Cd2+ ranged from 0.5 mg L-1 to 30 mg L-1. The detection limits were determined to be 0.2 mg L-1 (S/N = 3) for Pb2+ and 0.1 mg L-1 (S/N = 3) for Cd2+ in the case of a deposition time of 180 s. It is worth mentioning that the G-MWCNTs modified electrodes were successfully applied to the simultaneous detection of Cd2+ and Pb2+ ions in real electroplating effluent samples containing lots of surface active impurities, showing a good application prospect in the determination of trace amounts of heavy metals.

Place, publisher, year, edition, pages
Elsevier, 2014
Keyword
Graphene-carbon nanotubes hybrid, Heavy metal ions, Differential pulse anodic stripping voltammetry, Detection
National Category
Analytical Chemistry
Identifiers
urn:nbn:se:kth:diva-203216 (URN)10.1016/j.aca.2014.09.010 (DOI)000344235900007 ()2-s2.0-84912090504 (Scopus ID)
Note

QC 20170317

Available from: 2017-03-14 Created: 2017-03-14 Last updated: 2017-11-29Bibliographically approved
2. Synthesis of a novel electrode material containing phytic acid-polyaniline nanofibers for simultaneous determination of cadmium and lead ions
Open this publication in new window or tab >>Synthesis of a novel electrode material containing phytic acid-polyaniline nanofibers for simultaneous determination of cadmium and lead ions
Show others...
2016 (English)In: Analytica Chimica Acta, ISSN 0003-2670, E-ISSN 1873-4324, Vol. 947, p. 32-41Article in journal (Refereed) Published
Abstract [en]

The development of nanostructured conducting polymers based materials for electrochemical applications has attracted intense attention due to their environmental stability, unique reversible redox properties, abundant electron active sites, rapid electron transfer and tunable conductivity. Here, a phytic acid doped polyaniline nanofibers based nanocomposite was synthesized using a simple and green method, the properties of the resulting nanomaterial was characterized by electrochemical impedance spectroscopy (EIS), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). A glassy carbon electrode modified by the nanocomposite was evaluated as a new platform for the simultaneous detection of trace amounts of Cd2+ and Pb2+ using differential pulse anodic stripping voltammetry (DPASV). The synergistic contribution from PANI nanofibers and phytic acid enhances the accumulation efficiency and the charge transfer rate of metal ions during the DPASV analysis. Under the optimal conditions, good linear relationships were obtained for Cd2+ in a range of 0.05–60 μg L−1, with the detection limit (S/N = 3) of 0.02 μg L−1, and for Pb2+ in a range of 0.1–60 μg L−1, with the detection limit (S/N = 3) of 0.05 μg L−1. The new electrode was successfully applied to real water samples for simultaneous detection of Cd2+ and Pb2+ with good recovery rates. Therefore, the new electrode material may be a capable candidate for the detection of trace levels of heavy metal ions.

Place, publisher, year, edition, pages
Elsevier, 2016
Keyword
Bismuth film electrode, Differential pulse anodic stripping voltammetry, Heavy metal ions, Phytic acid, Polyaniline nanofibers, Simultaneous determination
National Category
Analytical Chemistry
Identifiers
urn:nbn:se:kth:diva-203218 (URN)10.1016/j.aca.2016.10.012 (DOI)000388108700005 ()2-s2.0-84995680331 (Scopus ID)
Note

QC 20170317

Available from: 2017-03-14 Created: 2017-03-14 Last updated: 2017-11-29Bibliographically approved
3. Towards the mechanism of electrochemical activity and self-healing of 1 wt% PTSA doped polyaniline in alkyd composite polymer coating: combined AFM-based studies
Open this publication in new window or tab >>Towards the mechanism of electrochemical activity and self-healing of 1 wt% PTSA doped polyaniline in alkyd composite polymer coating: combined AFM-based studies
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2016 (English)In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, no 23, p. 19111-19127Article in journal (Refereed) Published
Abstract [en]

A composite solvent-borne alkyd coating with 1 wt% p-toluene sulfonic acid (PTSA) doped polyaniline (PANI) was prepared. The mechanisms of electrochemical activity and self-healing properties of the composite coating were investigated by in situ atomic force microscopy (AFM), intermodulation AFM (ImAFM), electrochemical controlled (EC)-AFM combined with cyclic voltammetry (CV), Kelvin force microscopy (KFM), and Fourier transform infrared spectroscopy (FTIR), as well as open-circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) methods. The ImAFM demonstrates the multiphase structure of the composite coating and a high compatibility between the doped PANI and alkyd matrix. The CV and EC-AFM results reveal a high electrochemical activity of the doped PANI in the composite coating as well as reversible redox reactions between the emeraldine salt (ES) and leuco emeraldine base (LB) forms. The Volta potential mapping of KFM demonstrates a strong self-healing ability of the doped PANI in air conditions. The good electrochemical connection between the fine network of PANI in the composite coating and metal surface underneath enable the occurrence of reversible redox reaction between the ES/LB forms of doped PANI and a concomitant release of dopant anions both in air and in 3 wt% NaCl solution as demonstrated by OCP and EIS results. These therefore lead to the strong passivation and self-healing effect of the composite coated on the carbon steel surface.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2016
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-183688 (URN)10.1039/c6ra00661b (DOI)000370710500042 ()2-s2.0-84958974224 (Scopus ID)
Note

QC 20160319

Available from: 2016-03-19 Created: 2016-03-18 Last updated: 2017-11-30Bibliographically approved
4. Local surface mechanical properties of PDMS-silica nanocomposite probed with Intermodulation AFM
Open this publication in new window or tab >>Local surface mechanical properties of PDMS-silica nanocomposite probed with Intermodulation AFM
Show others...
(English)Manuscript (preprint) (Other academic)
National Category
Materials Chemistry
Identifiers
urn:nbn:se:kth:diva-203221 (URN)
Note

QC 20170317

Available from: 2017-03-14 Created: 2017-03-14 Last updated: 2017-03-17Bibliographically approved
5. Temperature-dependent surface nanomechanical properties of a thermoplastic nanocomposite
Open this publication in new window or tab >>Temperature-dependent surface nanomechanical properties of a thermoplastic nanocomposite
Show others...
2017 (English)In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 494, p. 204-214Article in journal (Refereed) Published
Abstract [en]

In polymer nanocomposites, particle-polymer interactions influence the properties of the matrix polymer next to the particle surface, providing different physicochemical properties than in the bulk matrix. This region is often referred to as the interphase, but detailed characterization of its properties remains a challenge. Here we employ two atomic force microscopy (AFM) force methods, differing by a factor of about 15 in probing rate, to directly measure the surface nanomechanical properties of the transition region between filler particle and matrix over a controlled temperature range. The nanocomposite consists of poly(ethyl methacrylate) (PEMA) and poly(isobutyl methacrylate) (PiBMA) with a high concentration of hydrophobized silica nanoparticles. Both AFM methods demonstrate that the interphase region around a 40-nm-sized particle located on the surface of the nanocomposite could extend to 55–70 nm, and the interphase exhibits a gradient distribution in surface nanomechanical properties. However, the slower probing rate provides somewhat lower numerical values for the surface stiffness. The analysis of the local glass transition temperature (Tg) of the interphase and the polymer matrix provides evidence for reduced stiffness of the polymer matrix at high particle concentration, a feature that we attribute to selective adsorption. These findings provide new insight into understanding the microstructure and mechanical properties of nanocomposites, which is of importance for designing nanomaterials.

Place, publisher, year, edition, pages
Academic Press, 2017
Keyword
Atomic force microscopy, Interphase, Nanomechanical properties, Thermoplastic nanocomposite
National Category
Materials Chemistry
Identifiers
urn:nbn:se:kth:diva-203220 (URN)10.1016/j.jcis.2017.01.096 (DOI)000395496900025 ()2-s2.0-85011072447 (Scopus ID)
Note

QC 20170317

Available from: 2017-03-14 Created: 2017-03-14 Last updated: 2017-04-25Bibliographically approved

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