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Kim, Young Yong,Kim, Kyungtae,Jung, Sungmin,Kim, Changsub,Kim, Jehan,Roth, Stephan V.,Sprung, Michael,Vartanyants, Ivan A.,Ree, Moonhor Elsevier 2016 Polymer Vol.105 No.-
<P><B>Abstract</B></P> <P>We investigated structural details and temperature-induced structural changes of an amorphous-crystalline brush diblock copolymer, poly(3-((6-((7-(9H-carbazol-9-yl)heptanoyl)oxy)hexyl)thio)propyl glycidyl ether)<SUB>60</SUB>-<I>b</I>-poly(glycidyl 12-((3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyl)oxy)-12-oxododecanoate)<SUB>20</SUB> (PGK<SUB>60</SUB>-PGF<SUB>20</SUB>) in nanoscale thin films using synchrotron grazing incidence X-ray scattering (GIXS) and X-ray photon correlation spectroscopy (XPCS). Interestingly, the diblock copolymer was found to form a mixture of two different hexagonal cylinder structures (HEX1 and HEX2) where the PGF cylinders were aligned in the film plane. HEX1 was composed of PGF cylinders with higher population of crystals while HEX2 consisted of PGF cylinders with lower population of crystals. Surprisingly, the PGF block chains favorably self-assembled because of strong lateral interactions in the bristles, forming vertical multibilayer structure with partial interdigitation even in the highly confined cylindrical geometry. In heating run up to 340 K, some fraction of HEX2 was transformed to HEX1 via cold crystallization. In contrast, HEX1 was transformed to HEX2 above 340 K because of melting of the PGF crystals. The XPCS analysis found that the HEX structural changes associated with the cold crystallization in the PGF cylinder domains took place with relatively fast dynamics. The HEX structural changes associated with melting of the PGF crystals in the cylinder domains occurred with relatively slow dynamics; this unusual dynamics of structural changes might be attributed to a high energy melting process of PGF crystals against strong lateral interactions of the bristles.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Hierarchical structure of an amorphous-crystalline brush diblock copolymer in nanoscale thin films was investigated. </LI> <LI> The crystallizable block chain makes two different hexagonal cylindrical packing orders. </LI> <LI> The fluoroalkyl containing brush block reveals strong tendency to crystallize even in confined cylindrical geometry. </LI> <LI> The fluoroalkyl containing brush block tends to undergo cold crystallization, causing a fast mode of structural changes. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Nanoscale thin film morphology details and temperature-induced structural changes of an amorphous-crystalline brush diblock copolymer containing carbazole and fluoroalkyl end groups at the bristle ends were investigated using synchrotron X-ray scattering and photon correlation spectroscopy.</P> <P>[DISPLAY OMISSION]</P>
Small-angle X-ray Scattering Beamline BL4C SAXS at Pohang Light Source II
Kwang-Woo Kim,Jehan Kim,Young Duck Yun,Hyungju Ahn,Byoungseok Min,Na Hyung Kim,Seungyu Rah,Hyo-Yun Kim,Chae-Soon Lee,In Deuk Seo,Woul-Woo Lee,Hyeong Joo Choi,Kyeong Sik Jin 한국구조생물학회 2017 Biodesign Vol.5 No.1
BL4C SAXS at the Pohang Light Source II is a small-angle X-ray scattering beamline based on an in-vacuum undulator insertion device, Si(111) DCM, and toroidal focusing mirror. The beamline normally provides high-flux synchrotron radiation X-ray sources with energies from 10.3 to 20.6 keV and a 100 µm (vertical) × 300 µm (horizontal) full width at half-maximum focal spot. The analysis of the SAXS data would be facilitated by means of useful ancillary equipment. The design of the beamline, the key components, and its role are described.
Kwon, Sooncheol,Park, Jin Kuen,Kim, Jehan,Kim, Geunjin,Yu, Kilho,Lee, Jinho,Jo, Yong-Ryun,Kim, Bong-Joong,Kang, Hongkyu,Kim, Junghwan,Kim, Heejoo,Lee, Kwanghee The Royal Society of Chemistry 2015 Journal of Materials Chemistry A Vol.3 No.15
<P>Processing additives have been widely utilized for high-performance organic bulk-heterojunction (BHJ) photovoltaic devices. However, the role of processing additives remained unclear due to the limited information relying on the final BHJ film state rather than the intermediate film state during solvent evaporation. Here, by using<I>in situ</I>GIWAXS measurements on the intermediate BHJ film, we propose a possible phase separation mechanism in efficient BHJ solar cells consisting of a narrow band gap polymer (P1) and PC71BM<I>via</I>the use of 1-chloronaphthalene (1-CN) as a processing additive. We found that adding small amounts of an additive, 1-CN, with a high boiling point and a high PC71BM solubility can prolong the solvent evaporation time and dissolve many PC71BM molecules, promoting the strong P1 polymer:solvent and PC71BM:solvent interaction to produce pure domains of each component. Thus, the bi-continuous networks for both P1 and PC71BM and their enlarged interfacial area are well fabricated in the BHJ films, inducing balanced photo-charge carrier densities for the electrons and holes and improving the overall photovoltaic performance. Therefore, our findings elucidate the kinetic motions of two organic phases affected by the physical properties of the solvents in the process of film formation and establish criteria for BHJ systems.</P>
Synchrotron Grazing Incidence X-ray Scattering and its Applications in Polymer Nanotechnology
Moonhor Ree,Byeongdu Lee,Jinhwan Yoon,Kyuyoung Heo,Kyeong Sik Jin,Sangwoo Jin,Hyunchul Kim,Ghahee Kim,Seung Chul Choi,Weontae Oh,Young-Hee Park,Yongtaek Hwang,Jong-Seong Kim,Jehan Kim,Kwang-Woo Kim,Ta 한국고분자학회 2006 한국고분자학회 학술대회 연구논문 초록집 Vol.2006 No.10
Kim, Tae-Hwan,Kang, Shin-Hyun,Doe, Changwoo,Yu, Jihyun,Sim, Jun-Bo,Kim, Jehan,Kline, Steven R.,Choi, Sung-Min American Chemical Society 2009 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.131 No.21
<P>Self-assembly of 1D nanoparticles such as carbon nanotubes or nanorods into highly ordered superstructures using various interactions has been of great interest as a route toward materials with new functionalities. However, the phase behavior of 1D nanoparticles interacting with surrounding materials, which is the key information to design self-assembled superstructures, has not been fully exploited yet. Here, we report for the first time a new phase diagram of negatively charged 1D nanoparticle and cationic liposome (CLs) complexes in water that exhibit three different highly ordered phases, intercalated lamellar, doubly intercalated lamellar, and centered rectangular phases, depending on particle curvature and electrostatic interactions. The new phase diagram can be used to understand and design new highly ordered self-assemblies of 1D nanoparticles in soft matter, which provide new functionalities.</P>
Lee, Ahreum,Kim, Yong C.,Baek, Keumjin,Alam, Jehan,Choi, Yun S.,Rheu, Yaeeun,Shin, Yoo Jin,Kim, Sungtae,Kim, Hyun-Duck,Song, Yeong W.,Choi, Youngnim TaylorFrancis 2018 Virulence Vol.9 No.1
<P><B>ABSTRACT</B></P><P>Autoantibodies against alpha-enolase (ENO1) are often detected in various infectious and autoimmune diseases. Anti-ENO1 antibody titers were reported to be associated with the severity of periodontitis in patients with rheumatoid arthritis. Because the enolase of the periodontal pathogen <I>Treponema denticola</I> (TdEno) has the highest homology with ENO1 among the enolases of human-associated bacteria, we hypothesized that anti-ENO1 autoantibodies produced during the immune response to TdEno may contribute to the progression of periodontitis and tested it in human and mouse systems. In human subjects with healthy periodontium or chronic periodontitis, a strong positive correlation between the levels of anti-TdEno and anti-ENO1 antibodies was observed. In addition, the purified anti-TdEno antibodies recognized ENO1 as well as TdEno in a dot blot, confirming the cross-reactivity between TdEno and ENO1. However, anti-ENO1 antibody titers were not associated with the severity of periodontitis. To further investigate the role of TdEno in the production of anti-ENO1 antibodies and the progression of periodontitis, mice received an oral gavage of <I>P. gingivalis</I> alone, subcutaneous immunization with TdEno alone, or both <I>P. gingivalis</I> oral gavage and TdEno immunization. Immunization with TdEno induced not only anti-TdEno but also anti-mouse Eno1 (mEno1) antibodies and increased the expression of TNFα in the gingival tissues. However, alveolar bone loss was not increased by TdEno immunization. In conclusion, autoreactive anti-ENO1/mEno1 antibodies that are produced as byproducts during the antibody response to TdEno play a minimal role in the progression of periodontitis in the absence of rheumatoid arthritis.</P>
Optically transparent semiconducting polymer nanonetwork for flexible and transparent electronics
Yu, Kilho,Park, Byoungwook,Kim, Geunjin,Kim, Chang-Hyun,Park, Sungjun,Kim, Jehan,Jung, Suhyun,Jeong, Soyeong,Kwon, Sooncheol,Kang, Hongkyu,Kim, Junghwan,Yoon, Myung-Han,Lee, Kwanghee National Academy of Sciences 2016 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.113 No.50
<P>Simultaneously achieving high optical transparency and excellent charge mobility in semiconducting polymers has presented a challenge for the application of these materials in future 'flexible' and 'transparent' electronics (FTEs). Here, by blending only a small amount (similar to 15 wt %) of a diketopyrrolopyrrole-based semiconducting polymer (DPP2T) into an inert polystyrene (PS) matrix, we introduce a polymer blend system that demonstrates both high field-effect transistor (FET) mobility and excellent optical transparency that approaches 100%. We discover that in a PS matrix, DPP2T forms a web-like, continuously connected nanonet-work that spreads throughout the thin film and provides highly efficient 2D charge pathways through extended intrachain conjugation. The remarkable physical properties achieved using our approach enable us to develop prototype high-performance FTE devices, including colorless all-polymer FET arrays and fully transparent FET-integrated polymer light-emitting diodes.</P>
Semiconducting Polymers with Nanocrystallites Interconnected via Boron-Doped Carbon Nanotubes
Yu, Kilho,Lee, Ju Min,Kim, Junghwan,Kim, Geunjin,Kang, Hongkyu,Park, Byoungwook,Ho Kahng, Yung,Kwon, Sooncheol,Lee, Sangchul,Lee, Byoung Hun,Kim, Jehan,Park, Hyung Il,Kim, Sang Ouk,Lee, Kwanghee American Chemical Society 2014 NANO LETTERS Vol.14 No.12
<P>Organic semiconductors are key building blocks for future electronic devices that require unprecedented properties of low-weight, flexibility, and portability. However, the low charge-carrier mobility and undesirable processing conditions limit their compatibility with low-cost, flexible, and printable electronics. Here, we present significantly enhanced field-effect mobility (μ<SUB>FET</SUB>) in semiconducting polymers mixed with boron-doped carbon nanotubes (B-CNTs). In contrast to undoped CNTs, which tend to form undesired aggregates, the B-CNTs exhibit an excellent dispersion in conjugated polymer matrices and improve the charge transport between polymer chains. Consequently, the B-CNT-mixed semiconducting polymers enable the fabrication of high-performance FETs on plastic substrates via a solution process; the μ<SUB>FET</SUB> of the resulting FETs reaches 7.2 cm<SUP>2</SUP> V<SUP>–1</SUP> s<SUP>–1</SUP>, which is the highest value reported for a flexible FET based on a semiconducting polymer. Our approach is applicable to various semiconducting polymers without any additional undesirable processing treatments, indicating its versatility, universality, and potential for high-performance printable electronics.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2014/nalefd.2014.14.issue-12/nl503574h/production/images/medium/nl-2014-03574h_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nl503574h'>ACS Electronic Supporting Info</A></P>
Kwon, Wonsang,Rho, Yecheol,Kamoshida, Kensuke,Kwon, Kyung Ho,Jeong, Youn Cheol,Kim, Jonghyun,Misaka, Hideki,Shin, Tae Joo,Kim, Jehan,Kim, Kwang‐,Woo,Jin, Kyeong Sik,Chang, Taihyun,Kim, Heesoo,Sa WILEY‐VCH Verlag 2012 Advanced Functional Materials Vol.22 No.24
<P><B>Abstract</B></P><P>Low‐temperature anionic ring‐opening homopolymerizations and copolymerizations of two glycidol derivatives (allyl glycidyl ether (AGE) and ethoxyethyl glycidyl ether (EEGE)) are studied using a metal‐free catalyst system, 3‐phenyl‐1‐propanol (PPA) (an initiator) and 1‐<I>tert</I>‐butyl‐4,4,4‐tris(dimethylamino)‐2,2‐bis[tris‐(dimethylamino)phosphoranylidenamino]‐2Λ<SUP>5</SUP>,4Λ<SUP>5</SUP>‐catenadi(phosphazene) (<I>t</I>‐Bu‐P<SUB>4</SUB>) (a promoter) in order to obtain well‐defined functional linear polyethers and diblock copolymers. With the aid of the catalyst system, AGE is found to successfully undergo anionic ring‐opening polymerization (ROP) even at room temperature (low reaction temperature) without any side reactions, producing well‐defined linear AGE‐homopolymer in a unimodal narrow molecular weight distribution. Under the same conditions, EEGE also undergoes polymerization, producing a linear EEGE‐homopolymer in a unimodal narrow molecular‐weight distribution. In this case, however, a side reaction (i.e., chain‐transfer reaction) is found to occur at low levels during the early stages of polymerization. The chemical properties of the monomers in the context of the homopolymerization reactions are considered in the design of a protocol used to synthesize well‐defined linear diblock copolyethers with a variety of compositions. The approach, anionic polymerization via the sequential step feed of AGE and EEGE as the first and second monomers, is found to be free from side reactions at room temperature. Each block of the obtained linear diblock copolymers undergoes selective deprotection to permit further chemical modification for selective functionalization. In addition, thermal properties and structures of the polymers and their post‐modification products are examined. Overall, this study demonstrates that a low‐temperature metal‐free anionic ROP using the PPA/<I>t</I>‐Bu‐P<SUB>4</SUB> catalyst system is suitable for the production of well‐defined linear AGE‐homopolymers and their diblock copolymers with the EEGE monomer, which are versatile and selectively functionalizable linear aliphatic polyether platforms for a variety of post‐modifications, nanostructures, and their applications.</P>