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Publications (10 of 30) Show all publications
Hakobyan, S., Rzhepishevska, O., Barbero, D. R. & Ramstedt, M. (2018). Functionalization of zwitterionic polymer brushes, do they remain antifouling?. Surface and Interface Analysis, 50(11), 1001-1006
Open this publication in new window or tab >>Functionalization of zwitterionic polymer brushes, do they remain antifouling?
2018 (English)In: Surface and Interface Analysis, ISSN 0142-2421, E-ISSN 1096-9918, Vol. 50, no 11, p. 1001-1006Article in journal (Refereed) Published
Abstract [en]

Polymer brushes are surface coatings that can be tailored in many ways to suit specific demands including reduction of protein and bacterial fouling of biomaterials. Previously, we reported that antifouling poly (2-(methacryloxy)ethyl)dimethyl-3-sulphopropyl ammonium hydroxide) brushes dramatically reduced formation of bacterial biofilm. We hypothesized that: (1) this brush could be efficiently functionalized with a small molecule (2-oxo-2-[N-(2,4,6-trihydroxybenzylidene)-hydrazino]-acetamide, ME0163, hydrazone) and that (2) the antifouling property would remain also after functionalization. Diblock co-polymer brushes of 2-(methacryloxy)ethyl)dimethyl-3-sulphopropyl ammonium hydroxide and poly (glycidyl methacrylate) were formed by surface-initiated atom transfer radical polymerization (SI-ATRP), and the ME0163 hydrazone was covalently bound to the surface via a ring-opening reaction. Functionalization of the surfaces was followed by X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and UV-Vis spectroscopy. The influence of temperature, reaction time, and reagent concentrations on the immobilization process was investigated. Surfaces with high degree of functionalization could be made in this way. However, the functionalization rendered the surface more hydrophobic, and the antifouling property of the brush was lost, thus, disproving the second of our starting hypotheses but corroborating the first.

Place, publisher, year, edition, pages
John Wiley & Sons, 2018
National Category
Chemical Sciences
Identifiers
urn:nbn:se:umu:diva-143891 (URN)10.1002/sia.6376 (DOI)000448889600005 ()
Funder
Swedish Research Council, 2011-3504The Kempe FoundationsStiftelsen Olle Engkvist Byggmästare, 2014/660
Note

SIA-17-0337.R1

Available from: 2018-01-12 Created: 2018-01-12 Last updated: 2018-11-22Bibliographically approved
Boulanger, N., Yu, V., Hilke, M., Toney, M. F. & Barbero, D. R. (2018). Graphene induced electrical percolation enables more efficient charge transport at a hybrid organic semiconductor/graphene interface. Physical Chemistry, Chemical Physics - PCCP, 20(6), 4422-4428
Open this publication in new window or tab >>Graphene induced electrical percolation enables more efficient charge transport at a hybrid organic semiconductor/graphene interface
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2018 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 20, no 6, p. 4422-4428Article in journal (Refereed) Published
Abstract [en]

Self-assembly of semiconducting polymer chains during crystallization from a liquid or melt dictates to a large degree the electronic properties of the resulting solid film. However, it is still unclear how charge transport pathways are created during crystallization. Here, we performed complementary in situ electrical measurements and synchrotron grazing incidence X-ray diffraction (GIXD), during slow cooling from the melt of highly regio-regular poly(3-hexylthiophene) (P3HT) films deposited on both graphene and on silicon. Two different charge transport mechanisms were identified, and were correlated to the difference in crystallites' orientations and overall amount of crystallites in the films on each surface as molecular self-assembly proceeded. On silicon, a weak charge transport was enabled as soon as the first edge-on lamellae formed, and further increased with the higher amount of crystallites (predominantly edge-on and randomly oriented lamellae) during cooling. On graphene however, the current remained low until a minimum amount of crystallites was reached, at which point interconnection of conducting units (face-on, randomly oriented lamellae and tie-chains) formed percolated conducting pathways across the film. This lead to a sudden rapid increase in current by approximate to 10 fold, and strongly enhanced charge transport, despite a much lower amount of crystallites than on silicon.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2018
National Category
Materials Chemistry Condensed Matter Physics
Identifiers
urn:nbn:se:umu:diva-145135 (URN)10.1039/c7cp07871d (DOI)000424357100060 ()29372204 (PubMedID)
Available from: 2018-03-05 Created: 2018-03-05 Last updated: 2018-06-09Bibliographically approved
Boulanger, N., Yu, V., Hilke, M., Toney, M. F. & Barbero, D. R. (2017). In situ probing of the crystallization kinetics of rr-P3HT on single layer graphene as a function of temperature. Physical Chemistry, Chemical Physics - PCCP, 19(12), 8496-8503
Open this publication in new window or tab >>In situ probing of the crystallization kinetics of rr-P3HT on single layer graphene as a function of temperature
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2017 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 19, no 12, p. 8496-8503Article in journal (Refereed) Published
Abstract [en]

We studied the molecular packing and crystallization of a highly regio-regular semiconducting polymer poly(3-hexylthiophene) (P3HT) on both single layer graphene and silicon as a function of temperature, during cooling from the melt. The onset of crystallization, crystallites' size, orientation, and kinetics of formation were measured in situ by synchrotron grazing incidence X-ray diffraction (GIXD) during cooling and revealed a very different crystallization process on each surface. A favored crystalline orientation with out of plane pi-pi stacking formed at a temperature of 200 degrees C on graphene, whereas the first crystallites formed with an edge-on orientation at 185 degrees C on silicon. The crystallization of face-on lamellae revealed two surprising effects during cooling: (a) a constant low value of the pi-pi spacing below 60 degrees C; and (b) a reduction by half in the coherence length of face-on lamellae from 100 to 30 degrees C, which corresponded with the weakening of the 2nd or 3rd order of the in-plane (k00) diffraction peak. The final ratio of face-on to edge-on orientations was 40% on graphene, and 2% on silicon, revealing the very different crystallization mechanisms. These results provide a better understanding of how surfaces with different chemistries and intermolecular interactions with the polythiophene polymer chains lead to different crystallization processes and crystallites orientations for specific electronic applications.

National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:umu:diva-133743 (URN)10.1039/c6cp08589j (DOI)000397860900042 ()28287217 (PubMedID)
Available from: 2017-05-09 Created: 2017-05-09 Last updated: 2018-06-09Bibliographically approved
Barbero, D. R. & Boulanger, N. (2017). Ultralow Percolation Threshold in Nanoconfined Domains. ACS Nano, 11(10), 9906-9913
Open this publication in new window or tab >>Ultralow Percolation Threshold in Nanoconfined Domains
2017 (English)In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 11, no 10, p. 9906-9913Article in journal (Refereed) Published
Abstract [en]

Self-assembled percolated networks play an important role in many advanced electronic materials and devices. In nanocarbon composites, decreasing the percolation threshold phi(c) is of paramount importance to reduce nanotube bundling, minimize material resources and costs, and enhance charge transport. Here we demonstrate that three-dimensional nanoconfinement in single-wall carbon nanotube/polymer nanocomposites produces a strong reduction in phi(c) reaching the lowest value ever reported in this system of phi(c) approximate to 1.8 X 10(-5) wt % and 4-5 orders of magnitude lower than the theoretical statistical percolation threshold oh phi(stat) Moreover, a change in network resistivity and electrical conduction was observed with increased confinement, and a simple resistive model is used to accurately estimate the difference in is in the confined networks. These results are explained in terms of networks' size, confinement, and tube orientation as determined by atomic force microscopy, electrical conductivity measurements, and polarized Raman spectroscopy. Our findings provide important insight into nanoscale percolated networks and should find application in electronic nanocomposites and devices.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2017
Keywords
carbon nanotubes, percolation, nanoconfinement, organic electronics, charge transport
National Category
Nano Technology
Identifiers
urn:nbn:se:umu:diva-141995 (URN)10.1021/acsnano.7b03851 (DOI)000413992800032 ()28949506 (PubMedID)
Available from: 2017-11-22 Created: 2017-11-22 Last updated: 2018-06-09Bibliographically approved
Kan, Z., Colella, L., Canesi, E. V., Vorobiev, A., Skrypnychuk, V., Terraneo, G., . . . Keivanidis, P. E. (2016). Charge transport control via polymer polymorph modulation in ternary organic photovoltaic composites. Journal of Materials Chemistry A, 4(4), 1195-1201
Open this publication in new window or tab >>Charge transport control via polymer polymorph modulation in ternary organic photovoltaic composites
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2016 (English)In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, no 4, p. 1195-1201Article in journal (Refereed) Published
Abstract [en]

The control on the charge transport properties of ternary organic photovoltaic P3HT : PCBM : QBT devices is enabled by modulating the distribution of P3HT polymorphs in the device photoactive layers. Negligible amounts of QBT induce striking modifications in the P3HT lamellar stacking direction, forming both densely packed and non-densely packed P3HT chains. The former reduce the charge carrier recombination rate, enabling an increased fill factor and short-circuit device photocurrent.

National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:umu:diva-129890 (URN)10.1039/c5ta08120c (DOI)000368837800006 ()
Available from: 2017-01-13 Created: 2017-01-10 Last updated: 2018-06-09Bibliographically approved
Barbero, D. R. & Stranks, S. D. (2016). Functional single-walled carbon nanotubes and nanoengineered networks for organic- and Perovskite-solar-cell applications. Advanced Materials, 28(44), 9668-9685
Open this publication in new window or tab >>Functional single-walled carbon nanotubes and nanoengineered networks for organic- and Perovskite-solar-cell applications
2016 (English)In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 28, no 44, p. 9668-9685Article in journal (Refereed) Published
Abstract [en]

Carbon nanotubes have a variety of remarkable electronic and mechanical properties that, in principle, lend them to promising optoelectronic applications. However, the field has been plagued by heterogeneity in the distributions of synthesized tubes and uncontrolled bundling, both of which have prevented nanotubes from reaching their full potential. Here, a variety of recently demonstrated solution-processing avenues is presented, which may combat these challenges through manipulation of nanoscale structures. Recent advances in polymer-wrapping of single-walled carbon nanotubes (SWNTs) are shown, along with how the resulting nanostructures can selectively disperse tubes while also exploiting the favorable properties of the polymer, such as light-harvesting ability. New methods to controllably form nanoengineered SWNT networks with controlled nanotube placement are discussed. These nanoengineered networks decrease bundling, lower the percolation threshold, and enable a strong enhancement in charge conductivity compared to random networks, making them potentially attractive for optoelectronic applications. Finally, SWNT applications, to date, in organic and perovskite photovoltaics are reviewed, and insights as to how the aforementioned recent advancements can lead to improved device performance provided.

National Category
Chemical Sciences
Identifiers
urn:nbn:se:umu:diva-131892 (URN)10.1002/adma.201600659 (DOI)000392721400002 ()27633954 (PubMedID)
Available from: 2017-02-23 Created: 2017-02-23 Last updated: 2018-06-09Bibliographically approved
Skrypnychuk, V., Boulanger, N., Yu, V., Hilke, M., Toney, M. & Barbero, D. R. (2016). Reduced crystallinity and enhanced charge transport by melt annealing of an organic semiconductor on single layer graphene. Journal of Materials Chemistry C, 4(19), 4143-4149
Open this publication in new window or tab >>Reduced crystallinity and enhanced charge transport by melt annealing of an organic semiconductor on single layer graphene
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2016 (English)In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 4, no 19, p. 4143-4149Article in journal (Refereed) Published
Abstract [en]

We report on the effect of the annealing temperature on the crystallization and the electrical properties of the semiconducting polymer poly(3-hexylthiophene) (P3HT) on single layer graphene. Electrical characterization showed that heating the P3HT film above the melting point (Tm) resulted in a higher vertical charge carrier mobility. Grazing incidence X-ray diffraction (GIXD) revealed that the film was actually less crystalline overall, but that it consisted of a much higher number of face-on crystallites. We moreover show that annealing above Tm removes the existing seeds still present in the film at lower temperatures and enhances face-on formation. These results provide a better understanding of the influence of the annealing temperature on polythiophene crystallization on graphene, and it shows that the annealing at higher temperature induces a more favorable crystalline orientation which enhances charge transport, despite the reduction in the overall crystallinity. These results should help in the design of more efficient graphene based organic electronic devices by controlling the crystalline morphology of the semiconducting film.

National Category
Materials Chemistry
Identifiers
urn:nbn:se:umu:diva-120203 (URN)10.1039/C6TC00625F (DOI)000376041700006 ()
Available from: 2016-05-11 Created: 2016-05-11 Last updated: 2018-06-07Bibliographically approved
Skrypnychuk, V., Wetzelaer, G.-J. A. H., Gordiichuk, P. I., Mannsfeld, S. C. B., Herrmann, A., Toney, M. F. & Barbero, D. R. (2016). Ultrahigh Mobility in an Organic Semiconductor by Vertical Chain Alignment. Advanced Materials, 28(12), 2359-2366
Open this publication in new window or tab >>Ultrahigh Mobility in an Organic Semiconductor by Vertical Chain Alignment
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2016 (English)In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 28, no 12, p. 2359-2366Article in journal (Refereed) Published
Abstract [en]

A method to produce highly efficient and long-range vertical charge transport is demonstrated in an undoped polythiophene thin film, with average mobilities above 3.1 cm(2) V-1 s(-1). These record high mobilities are achieved by controlled orientation of the polymer crystallites enabling the most efficient and fastest charge transport along the chain backbones and across multiple chains. The significant increase in mobility shown here may present a new route to producing faster and more efficient optoelectronic devices based on organic materials. [GRAPHICS] .

National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:umu:diva-119277 (URN)10.1002/adma.201503422 (DOI)000372459600009 ()26813586 (PubMedID)
Available from: 2016-06-02 Created: 2016-04-15 Last updated: 2018-06-07Bibliographically approved
Ruhal, R., Antti, H., Rzhepishevska, O., Boulanger, N., Barbero, D. R., Wai, S. N., . . . Ramstedt, M. (2015). A multivariate approach to correlate bacterial surface properties to biofilm formation by lipopolysaccharide mutants of Pseudomonas aeruginosa. Colloids and Surfaces B: Biointerfaces, 127(0), 182-191
Open this publication in new window or tab >>A multivariate approach to correlate bacterial surface properties to biofilm formation by lipopolysaccharide mutants of Pseudomonas aeruginosa
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2015 (English)In: Colloids and Surfaces B: Biointerfaces, ISSN 0927-7765, E-ISSN 1873-4367, Vol. 127, no 0, p. 182-191Article in journal (Refereed) Published
Abstract [en]

Abstract Bacterial biofilms are involved in various medical infections and for this reason it is of great importance to better understand the process of biofilm formation in order to eradicate or mitigate it. It is a very complex process and a large range of variables have been suggested to influence biofilm formation. However, their internal importance is still not well understood. In the present study, a range of surface properties of Pseudomonas aeruginosa lipopolysaccharide mutants were studied in relation to biofilm formation measured in different kinds of multi-well plates and growth conditions in order to better understand the complexity of biofilm formation. Multivariate analysis was used to simultaneously evaluate the role of a range of physiochemical parameters under different conditions. Our results suggest the presence of serum inhibited biofilm formation due to changes in twitching motility. From the multivariate analysis it was observed that the most important parameters, positively correlated to biofilm formation on two types of plates, were high hydrophobicity, near neutral zeta potential and motility. Negative correlation was observed with cell aggregation, as well as formation of outer membrane vesicles and exopolysaccharides. This work shows that the complexity of biofilm formation can be better understood using a multivariate approach that can interpret and rank the importance of different factors being present simultaneously under several different environmental conditions, enabling a better understanding of this complex process.

Place, publisher, year, edition, pages
Elsevier, 2015
Keywords
Pseudomonas aeruginosa, Biofilm, LPS mutant, Multivariate analysis, Bacterial surface properties
National Category
Chemical Sciences
Identifiers
urn:nbn:se:umu:diva-100362 (URN)10.1016/j.colsurfb.2015.01.030 (DOI)000353001400024 ()25679490 (PubMedID)
Available from: 2015-03-02 Created: 2015-03-02 Last updated: 2018-06-07Bibliographically approved
Skrypnychuk, V., Boulanger, N., Yu, V., Hilke, M., Mannsfeld, S. C. B., Toney, M. F. & Barbero, D. R. (2015). Enhanced Vertical Charge Transport in a Semiconducting P3HT Thin Film on Single Layer Graphene. Advanced Functional Materials, 25(5), 664-670
Open this publication in new window or tab >>Enhanced Vertical Charge Transport in a Semiconducting P3HT Thin Film on Single Layer Graphene
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2015 (English)In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 25, no 5, p. 664-670Article in journal (Refereed) Published
Abstract [en]

The crystallization and electrical characterization of the semiconducting polymer poly(3-hexylthiophene) (P3HT) on a single layer graphene sheet is reported. Grazing incidence X-ray diffraction revealed that P3HT crystallizes with a mixture of face-on and edge-on lamellar orientations on graphene compared to mainly edge-on on a silicon substrate. Moreover, whereas ultrathin (10 nm) P3HT films form well oriented face-on and edge-on lamellae, thicker (50 nm) films form a mosaic of lamellae oriented at different angles from the graphene substrate. This mosaic of crystallites with - stacking oriented homogeneously at various angles inside the film favors the creation of a continuous pathway of interconnected crystallites, and results in a strong enhancement in vertical charge transport and charge carrier mobility in the thicker P3HT film. These results provide a better understanding of polythiophene crystallization on graphene, and should help the design of more efficient graphene based organic devices by control of the crystallinity of the semiconducting film.

Keywords
graphene, organic semiconductor, P3HT, crystallization, charge transport
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:umu:diva-100760 (URN)10.1002/adfm.201403418 (DOI)000349225400001 ()
Available from: 2015-04-26 Created: 2015-03-09 Last updated: 2018-06-07Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0001-5320-4769

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