Seismic stratigraphy and depositional history of late Quaternary deposits in a tide-dominated setting: An example from the eastern Yellow Sea

Yoo, D.G.,Lee, G.S.,Kim, G.Y.,Kang, N.K.,Yi, B.Y.,Kim, Y.J.,Chun, J.H.,Kong, G.S. Butterworth Scientific Ltd 2016 Marine and petroleum geology Vol.73 No.-

<P>Analysis of high-resolution seismic profiles and sediment data from the eastern Yellow Sea reveals that the late Quaternary deposits comprise six seismic units, interpreted as transgressive and highstand systems tracts formed since the LGM. Each unit was deposited during distinctive portions of the sea-level curve associated with hydrodynamic conditions. During the LGM (>19 ka BP), the study area was completely exposed, resulting in subaerial erosion associated with paleo-channel incision by the Huanghe and Korean Rivers. As the shelf was flooded, the incised channels were backfilled fluvial or coastal sediments, forming incised channel-fill deposits (SU1). The paleo-river may have supplied abundant terrigenous sediments to the study area around the paleo-river mouth and adjacent area. These sediments were trapped within the paleo-estuary and formed SU2, regarded as an estuarine deposit. Two types of serial sand ridges (SU3 and SU5) which correspond to transgressive deposits developed. SU3 on the southern part, west of Jeju Island (80-110 m deep) is regarded as a moribund type mainly formed during the early to middle stage of transgression. These are thought to have ceased growing and remobilizing. In contrast, SU5 (occurring 30-50 m deep off the Korean Peninsula) is generally regarded as active sand ridges deposited during the late stage of transgression and is partly modified by modern tidal currents. As the transgression continued, the near-surface sediments were reworked and redistributed by shelf erosion, resulting in a thin veneer of transgressive sands (SU4). The uppermost unit (SU6) formed the Heuksan Mud Belt (HMB), which is one of the most prominent mud deposits in the Yellow Sea. The lower part of the HMD corresponds to shelf-mud deposited during the late stage of transgression, whereas the upper part consists of a recent shelf-delta developed after the highstand sea level at about 7 ka BP. (C) 2016 Elsevier Ltd. All rights reserved.</P>

Polyaniline decorated honeycomb-patterned pores: Use of a reactive vapor in breath figure method

Male, Umashankar,Shin, Bo Kyoung,Huh, Do Sung Butterworth Scientific Ltd. etc. 2017 Polymer Vol. No.

<P><B>Abstract</B></P> <P>A new strategy is proposed to obtain pore functionalized honeycomb-patterned porous films by in-situ polymerization during breath figure process. The polystyrene with benzoyl peroxide mixture in chloroform was casted under reactive vapor conditions, generated by pumping air through aqueous aniline hydrochloride solution. The resulting films showed honeycomb patterned porous morphology with polyaniline functionalized pores. The formation of polyaniline was confirmed from color, conductivity, and UV-Visible studies. The strategy can be extended to obtain various pore functionalized films by choosing one reactant in polymer solution and other in humid vapors.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Pore functionalized ordered porous films by reactive vapor in breath figure method. </LI> <LI> It was possible by coupling interfacial polymerization with breath figure method. </LI> <LI> Functionalization achieved at condensed reactive droplet/polymer solution interface. </LI> <LI> The strategy can be applied to obtain a wide variety of pore functionalized films. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Thermally reversible self-healing polysilsesquioxane structure-property relationships based on Diels-Alder chemistry

Jo, Young Yeol,Lee, Albert S.,Baek, Kyung-Youl,Lee, Heon,Hwang, Seung Sang Butterworth Scientific Ltd. etc. 2017 Polymer Vol. No.

<P><B>Abstract</B></P> <P>An in-depth examination of the self-healing properties of both dienophile and diene functionalized ladder-like structured polysilsesquioxane copolymers and terpolymers was investigated. Through functionalization of both diene and dienophile on the double-stranded siloxane backbone with ternary n-alkyl functional groups acting as chain mobility control, the effect of chain mobility and chemical structure on self-healing and mechanical properties were elucidated. All of the single component self-healing hybrid materials exhibited fast healing times (∼5 min), and their de-crosslinked adducts exhibited exceptional retention of solubility in common organic solvents for good reusability, all while having inherent high thermal stability and optical transparency.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A series of singular component self-healing polysilsesquioxanes were synthesized. </LI> <LI> Highly reversible Diels-Alder/retro-Diels-Alder chemistry enabled self-healing. </LI> <LI> Effect of chain mobility and interchain distance were examined. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Hybrid ionogels derived from polycationic polysilsesquioxanes for lithium ion batteries

Lee, Jin Hong,Lee, Albert S.,Hong, Soon Man,Hwang, Seung Sang,Koo, Chong Min Butterworth Scientific Ltd. etc. 2017 Polymer Vol. No.

<P><B>Abstract</B></P> <P>A multifunctional crosslinkable and ionic-group functionalized ladder-like polysilsesquioxane was synthesized and utilized for the fabrication of hybrid ionogels for lithium ion batteries. The ionic-group functionalized ladder-like polysilsesquioxane combined the synergistic effects of hybrid materials in improving the thermal stability of conventional battery electrolytes, whilst maintain facile solution processability and chemically crosslinkable function in ionic conducting ionic liquid electrolyte media. Fabricated iongel electrolytes exhibiting exceptional thermal stability, mechanical properties, high ionic conductivity, and electrochemical stability. Lithium ion batteries fabricated with the hybrid ionic ladder-like polysilsesquioxane ionogels exhibited initial discharge capacities on par with neat liquid electrolytes, good rate performance, as well as stable cyclability and excellent Coulombic efficiency.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A crosslinkable ionic group-functionalized polysilsesquioxane was synthesized. </LI> <LI> Ionic polysilsesquioxane was utilized to fabricate ionogels for lithium batteries. </LI> <LI> Hybrid ionogels exhibited thermal, mechanical, and electrochemical stability. </LI> <LI> Hybrid ionogels exhibited excellent lithium ion battery performance. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Diffusion-assisted post-crosslinking of polymer microspheres containing epoxy functional groups

Oh, Joon-Suk,Kim, Minsoo P.,Kim, Joo-Hyung,Son, Hyunjong,Kim, Kyung-Heum,Kim, Sang-Hoon,Yoo, Ji-Beom,Lee, Youngkwan,Yi, Gi-Ra,Nam, Jae-Do Butterworth Scientific Ltd. etc. 2017 Polymer Vol. No.

<P><B>Abstract</B></P> <P>With a diffusion-assisted post-crosslinking method, polymer microspheres containing epoxy groups are crosslinked with ethylenediamine (EDA), gradually diffusing and reacting in the particles <I>via</I> amine/epoxy ring-opening reactions as confirmed by FT-IR and DSC results. Using a microcompression test, we find that the mechanical property (deformability under different applied force, breaking points, and recoverability) of the crosslinked microspheres is varied when different amounts of EDA are used in the system, resulting from different crosslinking density of the particles. An additional feature of the EDA treatment is to generate amine groups on the surface of the microspheres, enabling us to produce hybrid microspheres. We exploit them as immobilization sites for gold nanoparticles, forming gold-coated crosslinked microspheres. We also introduce a sequential functionalization method to fabricate crosslinked microspheres with selective functional groups on the surface. This approach can be a facile method to produce functional microspheres with controlled mechanical and surface properties.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A synchronous crosslinking and amine-functionalization method for the polymer microsphere is introduced. </LI> <LI> The method allows us to readily adjust the mechanical property of polymer particles. </LI> <LI> Free amine functional groups on the surface of the microspheres can immobilize Au NPs. </LI> <LI> A sequential functionalization method is introduced to selectively functionalize the surface and to crosslink the interior. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Synthesis of highly functionalized thermoplastic polyurethanes and their potential applications

Choi, J.,Moon, D.S.,Jang, J.U.,Yin, W.B.,Lee, B.,Lee, K.J. Butterworth Scientific Ltd. etc. 2017 Polymer Vol. No.

In general, thermoplastic polyurethane (TPU) is one of the polymers that have great flexibility and processibility. Along with these advantages, when the TPU contains specific functional groups for further reactions, the scope of application will be greatly extended. Here, we attempted to synthesize a highly functional TPU with a reactive group from the synthesized azido diol. Azido-thermoplastic polyurethanes (azido-TPUs), which could be introduced with other groups easily via azido-alkyne ''click'' reactions, have been studied. Because of their great processibility (even after functionalization), we can prepare azido-TPU films and fibers by spin coating and electrospinning, respectively. To prove the potential applications of azido-TPU, we investigated the mechanical properties of functionalized TPU and application via click reaction on TPU fibers and films.

Effect of alumina composition and surface integrity in alumina/epoxy composites on the ultrasonic attenuation properties

Cho, E.,Park, G.,Lee, J.W.,Cho, S.M.,Kim, T.,Kim, J.,Choi, W.,Ohm, W.S.,Kang, S. Butterworth Scientific Ltd., etc.] 2016 Ultrasonics Vol.66 No.-

We report a method of fabricating backing blocks for ultrasonic imaging transducers, using alumina/epoxy composites. Backing blocks contain scatterers such as alumina particles interspersed in the epoxy matrix for the effective scattering and attenuation of ultrasound. Here, the surface integrity can be an issue, where the composite material may be damaged during machining because of differences in strength, hardness and brittleness of the hard alumina particles and the soft epoxy matrix. Poor surface integrity results in the formation of air cavities between the backing block and the piezoelectric element upon assembly, hence the increased reflection off the backing block and the eventual degradation in image quality. Furthermore, with an issue of poor surface integrity due to machining, it is difficult to increase alumina as scatterers more than a specific mass fraction ratio. In this study, we increased the portion of alumina within epoxy matrix by obtaining an enhanced surface integrity using a net shape fabrication method, and verified that this method could allow us to achieve higher ultrasonic attenuation. Backing blocks were net-shaped with various mass fractions of alumina to characterize the formability and the mechanical properties, including hardness, surface roughness and the internal micro-structure, which were compared with those of machined backing blocks. The ultrasonic attenuation property of the backing blocks was also measured.

Hydrodynamic fluorescence emission behavior of molecular rotor-based vinyl polymers used as viscosity sensors

Jin, Young-Jae,Park, Hyosang,Ohk, Young-Jin,Kwak, Giseop Butterworth Scientific Ltd. etc. 2017 Polymer Vol.132 No.-

<P><B>Abstract</B></P> <P>A molecular rotor compound containing an allyl group (aMR) was synthesized and copolymerized with the vinyl monomers methyl methacrylate (MMA), styrene (St), and 2-hydroxyethyl methacrylate (HEMA). The absorption and fluorescence (FL) emission maxima of the solution of aMR in THF were observed at 445 and 485 nm, respectively. The FL quantum yield (FLQY) of aMR in THF was quite low (0.21%). However, it was found that the FL intensity significantly increased as the viscosity of the fluid increased. This change was expressed using the Förster-Hoffmann equation, log <I>I</I> = <I>C</I> + <I>x</I> log <I>η</I>, where <I>I</I> and <I>η</I> are the FL intensity of the probe and the viscosity of the fluid, respectively. The value of <I>x</I> was determined to be 0.66 and 0.53 for the methanol/ethylene glycol mixtures and alcohols, respectively. The absorption and FL emission spectra of the aMR-incorporated vinyl polymers were almost similar to those of aMR. The FLQYs of P(MMA-<I>co</I>-aMR), P(St-<I>co</I>-aMR), P(HEMA-<I>co</I>-MMA-<I>co</I>-aMR) films were 4.9, 4.3, and 5.1%, respectively. These FLQYs are ∼10 times of the values obtained with their solutions. As soon as the polymer film came into contact with the fluids, its FL emission started to decrease and reached an equilibrium state after a few minutes. It was found that the equilibrium FL emission became weaker as the viscosity of fluid decreased. The FL intensity ratio was also expressed using the modified Förster-Hoffmann equation. The <I>x</I> values of P(MMA-<I>co</I>-aMR) for alcohols and methanol/ethylene glycol mixtures, P(St-<I>co</I>-aMR) for hydrocarbons, and P(HEMA-<I>co</I>-MMA-<I>co</I>-aMR) for the methanol/ethylene glycol mixtures were 0.26, 0.24, 0.29, and 0.53 respectively.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A fluorescent molecular rotor was incorporated into various vinyl polymers by copolymerization method. </LI> <LI> The polymer films had much greater fluorescence (FL) quantum yields relative to the solutions. </LI> <LI> When the films were exposed to fluids, the FL emission became weaker as the viscosity of fluid decreased. </LI> <LI> The FL intensity ratios were expressed as a modified Förster -Hoffmann equation and showed high viscosity sensing abilities. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Ultra-fast bull's eye-like self-healing using CNT heater

Kim, Heejin,Yarin, Alexander L.,Lee, Min Wook Butterworth Scientific Ltd. etc. 2019 Polymer Vol.180 No.-

<P><B>Abstract</B></P> <P>In the present work, carbon nanotubes (CNTs) are dispersed in the polydimethylsiloxane (PDMS) matrix and used as an embedded heating source. The electrically conductive CNT layer provides the Joule heating of the released healing materials into cracks. This accelerates the release and polymerization (self-healing) rates. It is demonstrated that with this modification the healing process, which originally required at least 24 h, is shortened to only 10 min. In addition, it is proved that this approach works very well even in the low-temperature environment, where otherwise, the healing efficiency is low because of the high viscosity of the healing agents and reduced rate of the polymerization reaction. The bull's eye-like geometry proposed in this work can be replicated to protect large areas.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The healing time is reduced remarkably from 24 h to 10 min with an improved toughness. </LI> <LI> This approach works very well even in the ice water bath (T~1 °C). </LI> <LI> The bull's eye-like unit geometry is replicable to protect large areas. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Facile fabrication of core-shell typed silica/poly(diphenylamine) composite microparticles and their electro-response

Jang, Hyo Seon,Kwon, Seung Hyuk,Lee, Jin Hyun,Choi, Hyoung Jin Butterworth Scientific Ltd. etc. 2019 Polymer Vol.182 No.-

<P><B>Abstract</B></P> <P>Novel semi-conductively encapsulated microspheres were fabricated by coating poly(diphenylamine) (PDPA) onto spherical silica particles <I>via</I> chemical oxidative polymerization. Their nanoscale-encapsulated spherical structure and PDPA shell thickness of approximately 30 nm were observed by both SEM and TEM. Fourier transform infrared spectroscopy confirmed the successful surface-modification of silica particles with PDPA, which was probably obtained through π−π* stacking interactions between the aromatic groups of PDPA and n-[3-(trimethoxysilyl) propyl]aniline as a grafting agent attached to the silica surface. Thermogravimetric analysis revealed the reasonable thermal stability of the fabricated particles. The electrorheological (ER) suspension (10 vol%) with the silica/PDPA composite microspheres was fabricated without a typically used de-doping process. Their dynamic and elastic yield stresses increased with applied electric field strength, following the power-law model (~E<SUP>1.5</SUP>). Their shear stress and their solid-like behavior were explained using the Herschel-Bulkley model and Schwarzl equation, respectively. The immediate and reversible response of the ER fluids was observed using on-off tests.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Core-shell structured silica/PDPA microparticles were synthesized as ER material. </LI> <LI> Silica/PDPA particle based ER fluid was fabricated without additional de-doping process of PDPA. </LI> <LI> Sensitivity and reversibility of the ER fluid were observed through an on-off test. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>