The development of polymer-filled composites with an extremely high thermal conductivity (TC) that is competitive with conventional metals is in great demand due to their cost-effective process, ...light weight, and easy shape-forming capability. A novel polymer composite with a large thermal conductivity of 153 W m
−1
K
−1
was prepared based on self-assembled block copolymer micelles containing two different fillers of micron-sized silver particles and multi-walled carbon nanotubes. Simple mechanical mixing of the components followed by conventional thermal compression at a low processing temperature of 160 °C produced a novel composite with both structural and thermal stability that is durable for high temperature operation up to 150 °C as well as multiple heating and cooling cycles of Δ
T
= 100 °C. The high performance in thermal conduction of our composite was mainly attributed to the facile deformation of Ag particles during the mixing in a viscous thermoplastic medium, combined with networked carbon nanotubes uniformly dispersed in the nanoscale structural matrix of block copolymer micelles responsible for its high temperature mechanical stability. Furthermore, micro-imprinting on the composite allowed for topographically periodic surface micropatterns, which offers broader suitability for numerous micro-opto-electronic systems.
A novel, polymer-filled composite with thermal conductivity of 153 W m
−1
K
−1
was developed by the blending block copolymer micelles, MWNTs and deformable Ag particles.
Supramolecular assembly through complementary interaction between molecular subgroups belonging to phase‐separating polymer species offers a great opportunity, not only for constructing nanoscale ...soft templates reminiscent of conventional block copolymer morphologies, but also for tailoring surface properties by facile removal of one of the structure components by cleaving complementary interactions. Herein we report the fabrication of a novel, organic, nanoporous film through supramolecular assembly of two complementarily, end‐interacting, mono‐end‐functionalized polymers under solvent annealing. The film of end‐functionalized polymer blends under solvent annealing yielded phase‐separated nanodomains that resemble nanoscopically ordered structures of block copolymers, but that are more advantageous due to easily cleavable and exchangeable links between the phase‐separated domains. The removal of one of the components of the precursor structure formed from the end‐functionalized polymers through cleavage of complementary interactions allowed us to fabricate mono‐ or multilayered nanoporous structures in which the chemically useful end‐functionalities of the remnant polymers are rich on the surface of the pores. The resultant, organic, nanoporous films with tailored surface functionality offer a useful platform for various chemical and biological applications.
A well‐organized, nanoporous, thin template was fabricated with control over both size and interdomain distance through conventional solution blending and spin‐coating by using two mono‐end‐functionalized polymers. A simple solvent‐vapor treatment not only improved the nanostructure formation, but also effectively removed one of the polymers, leading to a nanoporous soft template with rich end functionalities on the surface of the pores (see figure).
Supramolecular assembly of end-functionalized polymers, forming block copolymer-like supramolecules based on ionic interaction, has been utilized as a simple and facile method for generating ...functionalized nanoporous thin film. Here, the binary blend film of aminated poly(ethylene oxide) dendrimer (APEO-G) and sulfonated polystyrene (SPS) at a stoichiometric composition after benzene/water solvent vapor annealing exhibits spherical domains in multilayers over a large area. By controlling the number of end-functional arms of dendrimer via divergent ring-opening polymerization of ethylene oxide as well as the molecular weights of SPS, the domain sizes can be controlled ranging from mainly 34 to 54 nm, even to 131 nm. Our supramolecular-assembly system provides an alternative approach to fabricating a functional nanotemplate by easily etching domains with selective solvent treatment and leaving functional groups at the pore surfaces.
We present a simple, but robust route to efficiently disperse very high rGO concentrations of chemically reduced graphene oxides (rGOs) in various non-polar solvents and polymers. Our method is based ...on the noncovalent, nondestructive modification of rGOs with a conjugated block copolymer, poly(styrene-block-paraphenylene) (PS-b-PPP). The dispersion of rGOs occurred because PPP blocks strongly adhered to basal planes of rGOs by pi - pi interactions, while PS blocks provided good solubility in a variety of non-polar environments. The resulting PS-b-PPP modified rGOs (PMrGOs) showed excellent solubility and dispersion stability that was dependent on the quality of the solvent with respect to the PS blocks. In particular, extremely high solubility of the rGOs, as high as 1.5 mg mL super(-1), was achieved in THF. Our PMrGOs and their solution blends with other non-polymer polymers such as PS, poly(methylmethacrylate) and poly(isoprene-block-styrene) were conveniently spin-coated on various substrates, giving rise to ultra-thin nanohybrid films where the amount of rGO can be systematically controlled. The scalable and simple strategy employed for fabricating rGO nanohybrid films allowed us to assemble a high performance non-volatile resistive polymer memory device in which the bias-dependent trapping and de-trapping of injected charges were efficiently manipulated on the surface of highly dispersed rGO sheets in the nanohybrid.
Polymer light-emitting diodes (PLEDs) have been of great interest for flexible mobile displays and large area solid-state lighting due to the possibility of achieving low production costs using ...solution processes combined with various printing technologies. Although monochromatic operation of PLEDs with high luminous efficiency and device stability has been achieved using numerous strategies, the development of color-tunable PLEDs capable of emitting a broad range of light upon the application of external stimuli still remains challenging. Here, we present a solution-processed broad range color-tunable tandem PLED of inverted and regular light emitting units (LEUs) stacked in series sharing a floating polymer electrode as a charge injection layer between two LEUs. Fine and broad wavelength color control from pure blue to pure orange is achieved when an AC field is applied with different positive-to-negative polarity heights in our tandem PLED. Our AC-driven tandem PLEDs offer a facile route to color-tunable polymer EL devices with a maximum current efficiency (CE) and luminance of 2.5 cd A
−1
and 1300 cd m
−2
for blue emission under DC reverse and 6.7 cd A
−1
and 6000 cd m
−2
for orange emission under DC forward as well as 3.1 cd A
−1
and 6000 cd m
−2
for white emission under AC, respectively.
Solution-processed electron-only tandem polymer light-emitting diodes were developed for broad wavelength light emission under AC operation.
We present a simple, but robust route to efficiently disperse very high rGO concentrations of chemically reduced graphene oxides (rGOs) in various non-polar solvents and polymers. Our method is based ...on the noncovalent, nondestructive modification of rGOs with a conjugated block copolymer, poly(styrene-
block
-paraphenylene) (PS-
b
-PPP). The dispersion of rGOs occurred because PPP blocks strongly adhered to basal planes of rGOs by π-π interactions, while PS blocks provided good solubility in a variety of non-polar environments. The resulting PS-
b
-PPP modified rGOs (PMrGOs) showed excellent solubility and dispersion stability that was dependent on the quality of the solvent with respect to the PS blocks. In particular, extremely high solubility of the rGOs, as high as 1.5 mg mL
−1
, was achieved in THF. Our PMrGOs and their solution blends with other non-polymer polymers such as PS, poly(methylmethacrylate) and poly(isoprene-
block
-styrene) were conveniently spin-coated on various substrates, giving rise to ultra-thin nanohybrid films where the amount of rGO can be systematically controlled. The scalable and simple strategy employed for fabricating rGO nanohybrid films allowed us to assemble a high performance non-volatile resistive polymer memory device in which the bias-dependent trapping and de-trapping of injected charges were efficiently manipulated on the surface of highly dispersed rGO sheets in the nanohybrid.
A highly efficient route to disperse rGOs in non-polar liquid and solid media was developed by non-covalent, nondestructive modification of rGOs with a conjugated block copolymer, poly(styrene-
block
-paraphenylene) (PS-
b
-PPP).
According to the ABA's Commission on Ethics 20/20, conducting fact investigations and discovery, and advising clients, "require lawyers to have a firm grasp on how electronic information is created, ...stored and retrieved.
A Tungsten-Halogen (TH) lamp is the most popular light source in NIR spectroscopy and hyperspectral imaging, which requires a warm-up to reach very high temperatures of up to 250 °C and take a long ...time for radiation stabilization. Consequently, it has a large enough volume to enable heat dissipation to prevent the thermal runaway of the electric circuit and turn out its power efficiency very low. These are major barriers for miniaturizing spectral systems and hyperspectral imaging devices. However, TH lamps can be replaced by pc-NIR LEDs in order to avoid high temperature and large volume. We compared the spectral emission of the available commercial pc-NIR LEDs under the same condition. As a replacement for the TH lamp, the VIS + NIR LED module was developed to combine a warm-white LED and pc-NIR LEDs. In order to feature out the availability of the VIS + NIR LED module against the TH lamp, they were used as the light source for evaluating the Soluble Solid Content (SSC) of an apple through VIS-NIR spectroscopy. The results show a remarkable feasibility in the performance of the partial least square (PLS) model using the VIS + NIR LED module; during PLS calibration, the correlation coefficient (R) values are 0.664 and 0.701, and the Mean Square Error (MSE) values are 0.681 and 0.602 for the TH lamp and VIS + NIR LED module, respectively. In VIS-NIR spectroscopy, this study indicates that the TH lamp could be replaceable with a warm-white LED and pc-NIR LEDs.
In this study, surface water samples were collected at sites located in the lowest reaches of closed (Geum) (i.e. with an estuary dam at the river mouth) and open (Seomjin) estuary systems between ...May 2016 and May 2018. We analyzed concentrations and stable isotopes of particulate organic carbon (POC) and dissolved organic carbon (DOC) to assess OC sources, to estimate fluxes of riverine OC, and to assess some of the factors driving OC exports in these two contrasting Korean estuary systems. Our geochemical results suggest that the contribution of the phytoplankton-derived POC to the total POC pool was larger in the Geum River than in the Seomjin River. Notably, a heavy riverine algae bloom occurred in the Geum River in August 2016, resulting in a high carbon isotopic composition (−19.4‰) together with low POC/PN ratio (<10) and POC/Chl-a ratio (<100). In contrast, potential DOC sources in both the Geum River and the Seomjin River were a mixture of C3-derived forest soils and cropland organic matter. During the study period, the catchment area-normalized fluxes of POC and DOC were 0.40 × 10−3 tC/km2/yr and 6.5 × 10−2 tC/km2/yr in the Geum River and 5.2 × 10−4 tC/km2/yr and 8.6 × 10−4 tC/km2/yr in the Seomjin River, respectively. It appears that the POC flux was more weakly associated with the water discharge in the Geum River than in the Seomjin River, but the DOC fluxes were in general controlled by the water discharges in both rivers. Accordingly, the estuary dam of the Geum River might be one of the most strongly influencing factors on seasonal patterns in POC fluxes into the adjacent coastal seas, strongly modifying water residence times and thus biogeochemical processes.
•Temporal variations in the source and flux of riverine POC and DOC were investigated in Geum and Seomjin estuaries.•The POC and DOC fluxes were estimated as 0.40 × 10-3 tC/km2/yr and 6.5 × 10-2 tC/km2/yr in the Geum River.•The POC and DOC fluxes were estimated as 5.2 × 10-4 tC/km2/yr and 8.6 × 10-4 tC/km2/yr in the Seomjin River.•The estuary dam mediates variations in the source and flux of POC in the Geum River.
Citrus fruits were sorted based on external qualities, such as size, weight, and color, and internal qualities, such as soluble solid content (SSC), acidity, and firmness. Visible and near-infrared ...(VNIR) hyperspectral imaging techniques were used as rapid and nondestructive techniques for determining the internal quality of fruits. The applicability of the VNIR hyperspectral imaging technique for predicting the SSC in citrus fruits was evaluated in this study. A VNIR hyperspectral imaging system with a wavelength range of 400-1000 nm and 100 W light source was used to acquire hyperspectral images from citrus fruits in two orientations (i.e., stem and calyx ends). The SSC prediction model was developed using partial least-squares regression (PLSR). Spectrum preprocessing, effective wavelength selection through competitive adaptive reweighted sampling (CARS), and outlier detection were used to improve the model performance. The performance of each model was evaluated using the coefficient of determination (R
) and root mean square error (RMSE). In the present study, the PLSR model was developed using only a citrus cultivar. The SSC prediction CARS-PLSR model with outliers removed exhibited R
and RMSE values of approximatively 0.75 and 0.56 °Brix, respectively. The results of this study are expected to be useful in similar fields such as agricultural and food post-harvest management, as well as in the development of an online system for determining the SSC of citrus fruits.
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