Browsing by Author "Lin, Chien-Min"

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Electrospinning of magnesium-ion linked binder-less PEDOT:PSS nanofibers for sensing organic gases
(2015-09-01)
Huang, Yi-Chia
;
Lo, Teng-Yuan
;
Chen, Chun-Hua
;
Wu, Kai-Hung
;
Lin, Chien-Min
Controlled and continuous electrospinning of approximately pure poly(3,4-ethylenedioxythiophene): poly( styrenesulfonate) (PEDOT:PSS) nanofibers has been successfully realized for the first time by alternating the great amount of conventional carrier polymers with only slight doping of magnesium nitrate which acts as a polymer cross-linker for significantly enhancing the entanglement of PEDOT:PSS. In contrast to the less response of the bulky PEDOT:PSS film, the electrospun PEDOT:PSS nanofibers exhibit remarkably high sensitivities and responding speeds in respectively sensing gas molecules of dimethylformamide (DMF), dimethyl sulfoxide (DMSO) and propylene carbonate (PC). (C) 2015 Elsevier B.V. All rights reserved.
Exploration of Energy Modulations in Novel RhB-TPE-Based Bichromophoric Materials via Interactions of Cu2+ Ion under Various Semiaqueous and Micellar Conditions
(2016-03-16)
Singh, Ravinder
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Dwivedi, Atul Kumar
;
Singh, Ashutosh
;
Lin, Chien-Min
;
Arumugaperumal, Reguram
Novel bichromophoric materials TR-A and TR-B consisting of an entirely new combination of TPE and RhB units were developed to explore the optimum conditions of energy modulations via pH variation and Cu2+ interaction at various water contents of CH3CN. Interestingly, TR-A and TR-B, at 60 and 70% water contents; respectively, favored the optimum Cu2+-mediated energy modulations from TPE to RhB and thus achieve the brightest orange emissions of free RhB with complete disappearance of aggregation-induced emission (AIE) from TPE. Furthermore, various micellar conditions of triton-X-100, SDS, and CTAB were employed to adjust energy modulations of TR-A and TR-B at high water contents (at 80 and 90%, respectively). The incorporation of RhB into triton-X-100 micellar cavities disrupted AIE from TPE; thus, none of the energy modulations from TPE to RhB occurred even in the presence of Cu2+ ion. Interestingly, the micellar conditions of anionic surfactant (SDS) favored the increased local concentration of Cu2+ ions in the vicinity of scavangable RhB and facilitated the generation of noncyclic free RhB in situ via bright-orange emissions.
Influence of terminal substituent on non-linear S-shaped oligomers consisting of azobenzene moieties at the peripheral arm: Synthesis, characterisation and phase transition behaviour
(2017-01-01)
Yeap, Guan-Yeow
;
Osman, Faridah
;
Ito, Keisuke
;
Takeuchi, Daisuke
;
Lin, Chien-Min
A series of symmetrical S-shaped mesogens based on 4,4-bis-(6-bromohexyloxy)biphenyl as a central unit containing two 2-{6-[4-(4-substitutedphenylazo)phenoxy]hexyloxy}phenol as side-chain groups has been successfully synthesised. The terminal substituent was varied from halogen (X=F, Cl, Br and I) to non-halogen (X=C2H5 and OC2H5). The oligomers with C2H5 and OC2H5 substituents exhibit predominantly the monotropic nematic (N) phase. The OC2H5-containing derivatives possess long-range stability of N phase than its C2H5-containing analogue in which it has small range of N phase stability. As for halogen-containing analogues, oligomer with F exhibits monotropic N phase whilst oligomers with Cl and Br exhibit monotropic N and smectic A (SmA) phases. In addition, homologue with Br shows additional phase which is smectic B (SmB) phase upon further cooling. However, the oligomers in which F, Cl and Br were substituted by I exhibits purely monotropic SmA and SmB phases. X-ray diffraction measurements reveal that the smectic phase is inclined to the monolayer structure.
Liquid crystalline non-linear S-shaped oligomers consisting of azobenzene and biphenylene units: synthesis, characterisation and influence of central spacer
(2017-01-01)
Osman, Faridah
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Yeap, Guan-Yeow
;
Maeta, Nobuyuki
;
Ito, Masato M.
;
Lin, Chien-Min
A series of non-linear S-shaped liquid crystal oligomers wherein the molecule consists of biphenylene moiety as a central core unit and two symmetrical side arms azobenzene moieties joined to catechol as a linkage group have been successfully synthesised and characterised. The members in this series possess different inner spacer with carbon number n ranging from 4 to 9 while the outer spacer length located in azobenzene moieties are remains unaltered. The members with even parity exhibit monotropic phase, whereas homologues with odd parity display enantiotropic phase. The appearance of nematic, smectic A and smectic B phases was validated with texture observation under polarised light and X-ray diffraction (XRD). The XRD study on the S-shaped oligomer indicates that the arrangement of smectic phase exists as an intercalated structure. The S-shaped oligomer shows photoisomerisation properties in solution whereby the trans to cis isomerisation for this molecule is accomplished 1140 s, whereas reverse process under thermal back reaction occurred in 4620 min. [GRAPHICS] .
Monomeric and aggregation emissions of tetraphenylethene in a photo-switchable polymer controlled by cyclization of diarylethene and solvent conditions
(2017-10-14)
Singh, Ravinder
;
Wu, Hsin-Yen
;
Dwivedi, Atul Kumar
;
Singh, Ashutosh
;
Lin, Chien-Min
A novel photo-switchable polymer P-PHT containing diarylethene (DAE) and tetraphenylethene (TPE) moieties and a triazole linker in the repeating unit was synthesized to study the aggregation-induced emission (AIE) behaviour of TPE with both the open and closed forms of DAE in P-PHT with high water contents. The photo-switching phenomena of DAE (from open to closed forms under UV-irradiation) in P-PHT were prominent in organic solvent (THF), high water contents (at 90% H2O) and acidic conditions. Upon UV-irradiation of P-PHT at 90% water content, the AIE of TPE was completely quenched via an energy transfer event from TPE to cyclized DAE. Interestingly, the rare monomeric emission of TPE was first discovered by the photo-cyclization of DAE in P-PHT compared with the AIE behaviour of TPE with the open form of DAE in P-PHT with AIE favourable conditions of high water content (90% H2O) and acidic conditions.
Novel supramolecular conjugated polyrotaxane as an acid-base controllable optical molecular switch
(2017-05-01)
Shukla, Tarun
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Arumugaperumal, Reguram
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Raghunath, Putikam
;
Lin, Ming-Chang
;
Lin, Chien-Min
To study the supramolecular interactions of the mechanically interlocked rotaxane pendants with the backbone of two comparable conjugated polymers, axle polymer P1 and polyrotaxane P2 were synthesized by copolymerization of fluorine-based monomer F with phenanthroimidazole (PIZ)-based axle monomer A and rotaxane monomer R, respectively. Prevailing H-1 NMR, UV-vis and PL profiles revealed that polyrotaxane P2 showed sensitive and reversible acid-base molecular switching properties via supramolecular interactions in contrast to the other analogous polymer P1. The capability of molecular switching is also proven by computational study. Apparently, the controllable nano self-assembly process of P2 was fulfilled by reversible acid-base molecular switch approaches, where the orthogonal H-bonded polyrotaxane units were converted from bloated form into flake form on protonation. (C) 2016 Elsevier B.V. All rights reserved.
Synthesis and enhanced electron transfer of supramolecular nano-composite containing dendritic dye and surface-modified ZnO nano-rods
(2018-10-01)
Lin, Chien-Min
;
Li, Ming-Shiou
;
Dwivedi, Atul Kumar
;
Lin, Hong-Cheu
;
材料科學與工程學系
Supramolecular nano-composites 15T5N/ZnOx-PNH containing enhanced compatibilities of dendritic dye 15T5N and surface-modified nano-rod ZnOx-PNH were developed in this study. The physical properties of supramolecular nano-composites have been well investigated by theoretical calculation and various measurements, including UV visible, PL, TEM, TCSPC, FT-IR, and CV. H-bonded nano-composite 15T5N/ZnO30-PNH possessed the saturated quenched fiuorscence as dendritic dye 15T5N complexed with surface-modified nano-rod ZnO30-PNH. In contrast to nano-rod mixture 15T5N/ZnO (without surface-modification), more widened visible absorption band to promote more efficient photo-induced charge separation phenomenon was observed in supramolecular nano-composite 15T5N/ZnO30-PNH. Compared with surfactant T-PNH, less efficient electron transfer of surfactant T-PC6 was observed in TCSPC and PL measurements because of the steric hindrance of long alkyl chains (-C6H13) attached to surfactant T-PC6. Therefore, the triple H-bonds between dendritic dye 15T5N and surface-modified nano-rod ZnO30-PNH are verified to result in the desirable effective electron transfer in supramolecular nano-composite 15T5N/ZnO30-PNH.
Synthesis and liquid crystalline studies of disc-shaped molecule on azo-bridged benzothiazole-phenyl ethers
(2016-11)
Yeap, Guan-Yeow
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Rahim, Mursyida Abdul
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Lin, Chien-Min
;
Lin, Hong-Cheu
;
Maeta, Nobuyuki
A new series of triphenylene core attached by six peripheral arms containing benzothiazole-azo with terminal ethoxy unit have successfully been synthesized and their liquid crystalline properties were characterized. The members in this series differ by the length of the methylene unit of-(CH2)(n)-, where n, varied following ascending order from 5 to 10. The molecular structure was characterized by elemental (C, H and N) analysis and spectroscopic methods including Fourier Transform Infrared (FT-IR) and Proton Nuclear Magnetic Resonance (H-1 NMR). The texture and the phase transition temperatures were investigated by using polarizing optical microscopy (POM) and differential scanning calorimetry (DSC). The disc-shape molecule with shorter spacer (n = 5) showed monotropic nematic phase. The higher homologues with n = 8-10 exhibited enantiotropic nematic phase and monotropic smectic C phase. The XRD diffraction studies further confirm the presence of smectic C without any discotic columnar phase. (C) 2016 Published by Elsevier B.V.
Synthesis and phase transition behaviours of laterally substituted liquid crystals containing methylhydroquinone: emerging of smectic C phase for higher homologues
(2017-01-01)
Seou, Chi-Kien
;
Ha, Sie-Tiong
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Lee, Siew-Ling
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Yeap, Guan-Yeow
;
Lin, Chien-Min
A series of laterally substituted low-molar-mass liquid crystals with molecular geometry were constructed with three phenyl rings bridged through ester central groups as the rigid core and a lateral methyl group as the flexible part of a molecule, with a view to understanding and establishing the effect of molecular structure on liquid crystal behaviour. Low-molar-mass mesogens known as 1,4-bis[(4-n-alkyloxybenzoyl)oxy]toluene with different number of carbon (n) at the alkyl chain have been prepared. Their molecular structures were proposed via physical measurements and spectroscopic techniques. Mesomorphic properties were studied by using differential scanning calorimetry, optical polarizing microscopy and powder X-ray diffraction techniques. The results showed that the melting points as well as the clearing temperatures decreased upon lengthening of the terminal alkyloxy chain lengths. Members with the shorter chain (n = 2-10) exhibited nematic phase. As for higher homologues, members with n = 12, 14, 16 and 18 showed polymorphism, whereby these compounds displayed both smectic and nematic properties.
Unveiling the influence of inner spacer length of the non-linear S-shaped chiral oligomers on liquid crystalline phase
(2017-06-01)
Yeap, Guan-Yeow
;
Osman, Faridah
;
Maeta, Nobuyuki
;
Ito, Masato M.
;
Lin, Chien-Min
A series of S-shaped liquid crystal oligomers consisting of biphenylene, catechol and cholesterol moieties have been synthesized and characterized. The members in this series differ by the length of inner spacers -(CH2)(n)-where n are varied from 4 to 9 whereas the outer spacer of undecanoate chain is remained intact. The texture and phase transition temperatures with associated enthalpy changes are recorded. Increase in the number of carbon atom at the inner spacer affects the stability of liquid crystalline phase. The homologues with shorter inner spacers n = 4 and 5 exhibit monotropic N* whilst the analogue with medium spacer n = 6 exhibits monotropic N* and SmC* phase. However, the oligomers with longer spacers n = 7, 8 and 9 exhibit enantiotropic N* and SmC* phase. The I -N* transition temperatures were found to depend on the parity of the inner spacers. An Xray diffraction study reveals that the S-shaped oligomers exist as a monolayer chiral smectic C phase. (C) 2017 Elsevier B.V. All rights reserved.