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Journal articleSchroeder BC, Li Z, Brady MA, et al., 2014, , Angewandte Chemie-International Edition, Vol: 53, Pages: 12870-12875, ISSN: 1521-3773
Cost-effective, solution-processable organic photovoltaics (OPV) present an interesting alternative to inorganic silicon-based solar cells. However, one of the major remaining challenges of OPV devices is their lack of long-term operational stability, especially at elevated temperatures. The synthesis of a fullerene dumbbell and its use as an additive in the active layer of a PCDTBT:PCBM-based OPV device is reported. The addition of only 20 % of this novel fullerene not only leads to improved device efficiencies, but more importantly also to a dramatic increase in morphological stability under simulated operating conditions. Dynamic secondary ion mass spectrometry (DSIMS) and TEM are used, amongst other techniques, to elucidate the origins of the improved morphological stability.
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Journal articleDattani R, Michels R, Nedoma AJ, et al., 2014, , Macromolecules, Vol: 47, Pages: 6113-6120, ISSN: 0024-9297
We report the polymer conformation and fullereneaggregation in a ternary system containing polystyrene, C60, andtoluene measured by small angle neutron, static, and dynamic lightscattering. We investigate polymer concentrations across the diluteand semidilute regime for five polymer molecular weights (Mw =20 kg/mol to 1 Mg/mol), and fullerene concentrations below andabove its miscibility threshold in toluene. We find that the polymerradius of gyration (Rgpoly), hydrodynamic radius (Rh), and themixture correlation length (ξ) remain unchanged upon addition ofC60. The miscibility of C60 in toluene, however, decreases upon addition of polystyrene forming aggregates with a timedependentradius on the order of 100 nm, and this effect is amplified with increasing polymer Mw. Our findings are relevant tothe solution processing of organic photovoltaics, which generally require the effective solubilization of fullerene derivatives andpolymer pairs in this concentration range.
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Journal articleDattani R, Bannock JH, Fei Z, et al., 2014, , JOURNAL OF MATERIALS CHEMISTRY A, Vol: 2, Pages: 14711-14719, ISSN: 2050-7488
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Journal articleGorgojo P, Karan S, Wong HC, et al., 2014, , Advanced Functional Materials, Vol: 24, Pages: 4729-4737, ISSN: 1616-3028
Organic solvent nanofiltration (OSN) membranes with ultrathin separation layers down to 35 nm in thickness fabricated from a polymer of intrinsic microporosity (PIM-1) are presented. These membranes exhibit exceptionally fast permeation of n-heptane with a rejection for hexaphenylbenzene of about 90%. A 35 nm thick PIM-1 membrane possesses a Young's modulus of 222 MPa, and shows excellent stability under hydraulic pressures of up to 15 bar in OSN. A maximum permeance for n-heptane of 18 Lm−2h−1bar−1 is achieved with a 140 nm thick membrane, which is about two orders of magnitude higher than Starmem240 (a commercial polyimide-based OSN membrane). Unexpectedly, decreasing the film thickness below 140 nm results in an anomalous decrease in permeance, which appears to be related to a packing enhancement of PIM-1, as measured by light interferometry. Further, thermal annealing of the membranes formed from PIM-1 reveals that their permeance is preserved up to temperatures in excess of 150 °C, whereas the permeance of conventional, integrally skinned, asymmetric polyimide OSN membranes decreases significantly when they are annealed under the same conditions. To rationalize this key difference in response of functional performance to annealing, the concept of membranes with intrinsic microporosity (MIMs) versus membranes with extrinsic microporosity (MEMs) is introduced.
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Journal articleWatanabe T, Lopez CG, Douglas JF, et al., 2014, , LANGMUIR, Vol: 30, Pages: 2470-2479, ISSN: 0743-7463
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- Citations: 47
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Journal articleBayley FA, Liao JL, Stavrinou PN, et al., 2014, , Soft Matter, Vol: 10, Pages: 1155-1166, ISSN: 1744-683X
We investigate the surface plasma oxidation of polydimethylsiloxane (PDMS) elastomers and its implication for the morphologies attainable by wrinkling of glassy-elastomer ‘bilayers’. The kinetics of glassy skin formation is found to follow a logarithmic dependence with plasma exposure time t and, for various plasma intensities I, the relevant control variable is shown to be dose (≡I × t). We model the mechanism and kinetics of glassy film formation by plasma oxidation with a frontal propagation coarse-grained model, describing the spatio-temporal evolution of a conversion order parameter (Ï•) orthogonal to the film surface. The model is validated by X-ray reflectivity experiments, which confirm the logarithmic growth and quantify the initial growth of a transient, incomplete, skin layer during the early stage of plasma exposure. Three regimes are identified as (I) induction, (II) formation and (III) propagation with a combination of X-ray and wrinkling experiments. The simultaneous increase in thickness and skin mechanical modulus is found to be responsible for an unexpected minimum wavelength λmin attainable, which depends on critical strain εc and is ultimately limited by mechanical failure of the elastomer (λmin ≃ 140 nm is demonstrated at ε = 200%). We conclude by establishing a 1D surface morphology diagram, in terms of wavelength λ and amplitude A, limitations and capabilities for producing highly ordered (sub-)micropatterns over macroscopic areas using plasma oxidised PDMS under uniaxial strain.
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Journal articleWong HC, Li Z, Tan CH, et al., 2014, , ACS NANO, Vol: 8, Pages: 1297-1308, ISSN: 1936-0851
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- Citations: 125
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Conference paperLivingston AG, Karan S, Gorgojo P, et al., 2014,
Microporosity in organic solvent nanofiltration membranes - Intrinsic or extrinsic?
, Pages: 127-128 -
Journal articleLi Z, Wong HC, Huang Z, et al., 2013, , NATURE COMMUNICATIONS, Vol: 4, ISSN: 2041-1723
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- Citations: 112
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Journal articleWong HC, Higgins AM, Wildes AR, et al., 2013, , ADVANCED MATERIALS, Vol: 25, Pages: 985-991, ISSN: 0935-9648
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- Citations: 34
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Journal articleRushworth CM, Davies J, Cabral JT, et al., 2012, , CHEMICAL PHYSICS LETTERS, Vol: 554, Pages: 1-14, ISSN: 0009-2614
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- Citations: 32
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Journal articleJames D, Oag B, Rushworth CM, et al., 2012, , RSC ADVANCES, Vol: 2, Pages: 5376-5384
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- Citations: 14
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Journal articleWong HC, Cabral JT, 2011, , MACROMOLECULES, Vol: 44, Pages: 4530-4537, ISSN: 0024-9297
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- Citations: 23
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Journal articleFrosch T, Chan KLA, Wong HC, et al., 2010, , LANGMUIR, Vol: 26, Pages: 19027-19032, ISSN: 0743-7463
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- Citations: 37
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Conference paperDavies J, Rushworth C, Vallance C, et al., 2010,
Drop kinetic analysis in real time by optical spectroscopy
, Pages: 330-332The spatio-temporal correspondence between microchannel position and reaction 'time' permits the study of kinetics of (chemical and physical) processes with unprecedented time resolution and dynamic range [1]. Monitoring reactions in real-time with non-invasive probes remains, hitherto, a major shortcoming of microchemical drop reactors due to the minute sample volumes (pL-nL) and fast travel speeds (1-1000 mm/s). We evaluate the potential of novel microdevice fabrication via frontal photopolymerisation (FPP) [2] integrated with Cavity Ring-Down Spectroscopy (CRDS) [3] for the online analysis of individual reaction travelling droplets.
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Journal articleChua Y-C, Chan A, Wong H-C, et al., 2010, , MACROMOLECULES, Vol: 43, Pages: 9578-9582, ISSN: 0024-9297
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- Citations: 8
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Journal articleWong HC, Cabral JT, 2010, , PHYSICAL REVIEW LETTERS, Vol: 105, ISSN: 0031-9007
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- Citations: 31
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Journal articleWong HC, Sanz A, Douglas JF, et al., 2010, , JOURNAL OF MOLECULAR LIQUIDS, Vol: 153, Pages: 79-87, ISSN: 0167-7322
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- Citations: 68
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Conference paperWong HC, Cabral JT, 2010, , 14th International Conference on Small-Angle Scattering (SAS09), Publisher: IOP PUBLISHING LTD, ISSN: 1742-6588
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- Citations: 10
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Conference paperMartin HP, Brooks NJ, Seddon JM, et al., 2010, , 14th International Conference on Small-Angle Scattering (SAS09), Publisher: IOP PUBLISHING LTD, ISSN: 1742-6588
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- Citations: 16
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Journal articleValera FE, Quaranta M, Moran A, et al., 2010, , ANGEWANDTE CHEMIE-INTERNATIONAL EDITION, Vol: 49, Pages: 2478-2485, ISSN: 1433-7851
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- Citations: 157
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Journal articleCabral JT, Higgins JS, 2009, , MACROMOLECULES, Vol: 42, Pages: 9528-9536, ISSN: 0024-9297
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- Citations: 19
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Journal articleYang G, Tang P, Yang Y, et al., 2009, , JOURNAL OF PHYSICAL CHEMISTRY B, Vol: 113, Pages: 14052-14061, ISSN: 1520-6106
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- Citations: 16
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Journal articleRogers SE, Terry AE, Lawrence MJ, et al., 2009, , MATERIALS TODAY, Vol: 12, Pages: 92-99, ISSN: 1369-7021
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- Citations: 1
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Journal articleTran MQ, Cabral JT, Shaffer MSP, et al., 2008, , NANO LETTERS, Vol: 8, Pages: 2744-2750, ISSN: 1530-6984
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- Citations: 70
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Conference paperSanz A, Ruppel M, Douglas JF, et al., 2008, , 4th European Conference on Neutron Scattering, Publisher: IOP PUBLISHING LTD, ISSN: 0953-8984
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- Citations: 48
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Journal articleChiche A, Stafford CM, Cabral JT, 2008, , SOFT MATTER, Vol: 4, Pages: 2360-2364, ISSN: 1744-683X
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- Citations: 115
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Conference paperAmis EJ, Beers KL, Hudson SD, 2006,
High throughput approaches to analysis of complex mixtures
, 231st National Meeting of the American-Chemical-Society, Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727 -
Journal articleCabral JT, Hudson SD, 2006,
Microfluidic approach for rapid multicomponent interfacial tensiometry
, Lab on A Chip, Vol: 6, Pages: 427-436, ISSN: 1473-0197 -
Journal articleVogel BM, Cabral JT, Eidelman N, et al., 2005, , JOURNAL OF COMBINATORIAL CHEMISTRY, Vol: 7, Pages: 921-928, ISSN: 1520-4766
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- Citations: 25
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