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Surface-mediated Photoalignment of Liquid Crystalline Polymers
Takahiro Seki 한국고분자학회 2021 한국고분자학회 학술대회 연구논문 초록집 Vol.46 No.1
Most polymer films have a free surface (surface exposed to the air). Recent studies have emphasized the importance of the free surface in many aspects of polymer processing. We have recently shown that the free surface plays the critical role in controlling the mesogen alignment of side chain liquid crystalline polymers (SCLCPs).<sup>1</sup> A skin layer (typically 20 nm thickness) or inkjet-printed pattern at the free surface is able to regulate the mesogen orientation of SCLCP films of micrometers thickness.<sup>2,3</sup> The mesogen orientation can be switched by the photo responsive top surface both in the in-plane<sup>2</sup> and out-of-plane3 directions. Another interesting aspect is the surface effect for the induction of surface morphing.<sup>4</sup> Surface relief grating formation could be performed also for a light-inert SCLCP films with a photo responsive surface skin layer.<sup>5</sup> (1) T. Seki, Bull. Chem. Soc. Jpn., 91, 1026 (2018); T. Seki, Polym. J., 46, 751 (2014); T. Seki, Macromol. Rapid Commun., 35, 271 (2014). (2) K. Fukuhara et al., Nat. Commun., 5, 3320 (2014). (3) T. Nakai et al., Langmuir, 32, 909 (2016). (4) I. Kitamura et al., Sci. Rep., 9, 2556 (2019). (5) I. Kitamura et al., Sci. Rep., 10, 12664 (2020).
Koh Kitagawa,Akira Mitoro,Takahiro Ozutsumi,Masanori Furukawa,Yukihisa Fujinaga,Kenichiro Seki,Norihisa Nishimura,Yasuhiko Sawada,Kosuke Kaji,Hideto Kawaratani,Hiroaki Takaya,Kei Moriya,Tadashi Namisa 대한소화기내시경학회 2022 Clinical Endoscopy Vol.55 No.3
Background/Aims: Covered self-expandable metallic stents (CMSs) are widely used for malignant distal biliary obstructions (MDBOs)caused by pancreatic carcinoma. This study compared the efficacy and safety of the laser-cut-type and braided-type CMSs. Methods: To palliate MDBOs caused by pancreatic carcinoma, the laser-cut-type CMSs was used from April 2014 to March 2017, andthe braided-type CMSs was used from April 2017 to March 2019. The tested self-expandable metallic stents were equipped with differentanti-migration systems. Results: In total, 47 patients received CMSs for MDBOs (24 laser-cut type, 23 braided-type). The time to recurrent biliary obstruction(TRBO) was significantly longer in the braided-type CMSs (p=0.0008), and the median time to stent dysfunction or patient death was141 and 265 days in the laser-cut-type CMSs and braided-type CMSs, respectively (p=0.0023). Stent migration was the major cause ofstent dysfunction in both groups, which occurred in 37.5% of the laser-cut-type CMSs and 13.0% of the braided-type CMSs. Therewere no differences in the survival duration between the groups. Conclusions: The TRBO was significantly longer for the braided-type CMSs with an anti-migration system than for the laser-cut-type. Stent migration tended to be less frequent with the braided-type CMSs than with the laser-cut-type CMSs.
Abe, Ikue,Hara, Mitsuo,Seki, Takahiro,Cho, Sung June,Shimizu, Masaki,Matsuura, Kazunori,Cheong, Hae-Kap,Kim, Jin Young,Oh, Jihun,Jung, Jaehoon,Han, Mina The Royal Society of Chemistry 2019 Journal of Materials Chemistry C Vol.7 No.8
<P>The design of light-responsive fluorescent assembly systems with a variety of photochemical and photophysical properties is important for the fundamental understanding of the assembly-disassembly process as well as for applications such as optical information storage and fluorescence sensing. A major obstacle in constructing such photofunctional materials is the lack of a molecular design strategy for photoswitchable organic chromophores with aggregation-induced emission/aggregation-induced emission enhancement (AIE/AIEE) characteristics. Herein, we describe a new trigonal azobenzene framework showing AIE/AIEE characteristics and excellent photoisomerization (∼90%) from the <I>C</I>3-symmetric to asymmetric (including a bent-shaped <I>cis</I>-azobenzene) form. NMR experiments demonstrate light-induced molecular structure changes, which cause drastic symmetry breaking. The trigonal chromophores assemble into red fluorescent microspheres and their fluorescence intensity increases by ∼10-fold, confirming the AIE/AIEE characteristics. Importantly, scanning electron microscopy (SEM), optical microscopy (OM), and fluorescence optical microscopy (FOM) images substantiate that a noticeable light-driven melting occurs simultaneously with a marked fluorescence switching from on to off. Moreover, the fluorescent spheres are successfully applied in optical information storage and fluorescence sensing in a non-contact fashion.</P>