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- 2019
- fan-in/out devices
- polymer optical waveguide
- the Mosquito method
- space division multiplexing
- Optoelectronic Information Science and Engineering
- Keio University
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Printing Birefringent Figures by Surface Tension-Directed Self-Assembly of a Cellulose Nanocrystal/Polymer Ink Components
摘要： Photonic printing on transparent substrates using emerging synthetic photonic crystals is in high demand, especially for anti-fraud applications. However, photonic printing is faced with grand challenges including lack of the full invisibility of printed patterns before stimulation or after stimuli removal and absence of the long-lasting stability. Natural anisotropic crystal structures and artificially molecularly arranged polymers show an optically anisotropic property known as birefringence. Crystalline cellulose is the most abundant birefringent bio-crystal on the earth. Here, we introduce a printing method based on using a cellulose nanocrystal/polymer ink that is governed by surface evaporation phenomenon and divided surface tension forces to direct the self-assembly of ink components at the nanoscale and print 3D birefringent micro-figures on transparent substrates. This type of printing is from now on referred to as Birefringent Printing (BP). Unlike previously reported photonic crystal printing methods, this method is accurate, has high-contrast, is virtually impossible to forge and at the same time is very simple, inexpensive and non-toxic.
关键词： polymer ink,cellulose nanocrystal,directed self-assembly,birefringence,surface tension,invisible printing
更新于2025-09-04 15:30:14
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Noncontact Imaging of Ion Dynamics in Polymer Electrolytes with Time-Resolved Electrostatic Force Microscopy
摘要： Ionic transport processes govern performance in many classic and emerging devices, ranging from battery storage to modern mixed-conduction electrochemical transistors. Here, we study local ion transport dynamics in polymer films using time-resolved electrostatic force microscopy (trEFM). We establish a correspondence between local and macroscopic measurements using local trEFM and macroscopic electrical impedance spectroscopy (EIS). We use polymer films doped with lithium bis(trifluoromethane)sulfonimide (LiTFSI) as a model system where the polymer backbone has oxanorbornenedicarboximide repeat units with an oligomeric ethylene oxide side chain of length n. Our results show that the local polymer response measured in the time domain with trEFM follows stretched exponential relaxation kinetics, consistent with the Havriliak-Negami relaxation we measure in the frequency-domain EIS data for macroscopic samples of the same polymers. Furthermore, we show that the trEFM results capture the same trends as the EIS results — changes in ion dynamics with increasing temperature, increasing salt concentration, and increasing volume fraction of ethylene oxide side chains in the polymer matrix evolve with the same trends in both measurement techniques. We conclude from this correlation that trEFM data reflect, at the nanoscale, the same ionic processes probed in conventional EIS at the device level. Finally, as an example application for emerging materials syntheses, we use trEFM and infrared photoinduced force microscopy (PiFM) to image a diblock copolymer electrolyte for next-generation solid-state energy storage applications.
关键词： scanning probe microscopy,ion dynamics,polymer electrolyte,diblock imaging,non-contact AFM
更新于2025-09-04 15:30:14
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Azulene’s D–A Structure for Optoelectronic Materials
摘要： Azulene’s D–A Structure for Optoelectronic Materials
关键词： OFET,azulene,n-type polymers,all-polymer solar cell
更新于2025-09-04 15:30:14
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Quartz-enhanced conductance spectroscopy for nanomechanical analysis of polymer wire
摘要： Quartz-enhanced conductance spectroscopy is developed as an analytical tool to investigate dynamic nanomechanical behaviors of polymer wires, in order to determine the glass transition temperature (Tg). A polymethyl methacrylate (PMMA) microwire with a diameter of 10 lm was bridged across the prongs of a quartz tuning fork (QTF). With the advantage of QTF self-sensing as compared with micro-cantilevers or other resonators, the resonance frequency and Q factor can be directly determined by means of its electrical conductance spectra with respect to the frequency of the external excitation source (dI/dV vs f), and therefore, no optical beam is required. The Tg of the PMMA microwire was determined by the maximum loss modulus of the QTF, calculated from the resonance frequency and the Q factor as a function of temperature. The measured Tg of the PMMA is 103 (cid:2)C with an error of 62 (cid:2)C. Both heating/cooling and physical aging experiments were carried out, demonstrating that the technique is both reversible and reproducible.
关键词： PMMA,polymer wire,quartz tuning fork,nanomechanical analysis,glass transition temperature,Quartz-enhanced conductance spectroscopy
更新于2025-09-04 15:30:14
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Experimental investigation on Heat Distortion Temperature parameter of Polymer Matrix Composites for solar Panel Applications
摘要： In this paper the examination intended to create polymer matrix composites with polyester and vinyl ester better warmth opposition. The glass fiber with polyester favoured with various piece of composite with expansion of various fillers in various weight parts was created. Created utilizing vacuum sack shaping procedure. The mechanical properties were assessed utilizing Universal testing machine and the warmth mutilation temperature is the temperature at which a polymer or plastic example disfigures under a predetermined load. This property of a given plastic material is connected in numerous parts of mechanical assembly with various loads. Better mechanical properties and wear properties were gotten with increment in weight level of auxiliary fortification substance. The Heat Distortion Temperature is controlled by the test strategy delineated in ASTM D648.Further it was discovered that The extent 40:60 and 20:80 does not framed as flawless IPN consequently it is discovered that 80% vinyl ester and 20%poyurethane have great flexibility and sturdiness in correlation with different proportions.
关键词： Tribology,and solar panel,Polymer matrix composite,Heat distortion
更新于2025-09-04 15:30:14
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A Two-Step Method for Stable and Impurity-Free Graphene Oxide Dispersion in Various Organic Solvents without a Stabilizer or Chemical Modification
摘要： The low stability of graphene oxide (GO) in organic solvents renders it unsuitable for several applications. Thus, an effective dispersion technique must be rapidly developed in order to allow the widespread use of GO. In this study, we successfully produced GO dispersions in various organic (including nonpolar) solvents without a stabilizer, chemical modification, or complex processing by a facile two-step method. In this technique, perfectly exfoliated single-layer GO was firstly prepared in water. Then, water was carefully replaced with each solvent. GO dispersed via this new method exhibited excellent long-term stability in organic solvents with a low impurity content. This is attributed to the release of interlayer water, which strongly links GO layers and causes aggregation in organic solvents, along with impurities trapped in interlayers during exfoliation. Additionally, a GO/polyvinyl chloride composite prepared using this new method showed better mechanical and electrical performances than prepared via the conventional method. The result obtained here will promote the widespread use of GO.
关键词： Organic solvent,polymer composite,Graphene oxide
更新于2025-09-04 15:30:14
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Synthesis and Characterization of novel Thiophene and Carbazole-based Polymers – Optical and Electrochemical Characterization
摘要： A donor/acceptor series of carbazole copolymers, composed of alternating 2,7-linked 3,6-difluoro-9-(1-octyl-nonyl)-carbazole units and bithiophene repeated units [P1], 5,7-bis(5-bromothiophen-2-yl)-2,3-bis(4-(2-ethylhexyloxy) phenyl) thieno[3,4-b]pyrazine repeated units [P2] and bithiophene mixed with thieno[3,4-b]pyrazine repeated units [P3] have been prepared following Suzuki polymerisation procedures. The route of synthesis and characterisation techniques of this novel class of materials, together with their photo-physical and electrochemical properties are presented in this study. The polymers were characterised by 1H NMR, 13C NMR and Elemental Analysis. Molecular weights were estimated using gel permeation chromatography (GPC). The thermal stability behaviour for polymers was investigated using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The electronic and photo-physical properties were investigated by use of cyclic voltammetry (CV) and UV-Vis spectroscopy, respectively.
关键词： Conjugated polymer,Organic solar cell,Band gap
更新于2025-09-04 15:30:14
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A Highly Fluorescent and Photoresponsive Polymer Gel Consisting of Poly(acrylic acid) and Supramolecular Cyanostilbene Crosslinkers
摘要： A poly(acrylic acid)-based polymer gel exhibiting strong fluorescence and high photoresponsibility is prepared by using a cyanostilbene derivative as a self-assembling supramolecular crosslinking agent, which generates conceptually new multiple hydrogen bonds in the gel system. This polymer gel in ethanol shows the gel-to-sol transition upon UV light irradiation with concomitant fluorescence color and intensity changes, which are attributed to the trans-to-cis photoisomerization of the supramolecular crosslinkers. Aggregation-induced enhanced emission (AIEE) behavior of the trans-cyanostilbene derivative enables a highly fluorescent polymer gel (ΦF = 0.68) with green color (λem = 541 nm), which can be switched into a blue fluorescent sol (λem = 506 nm and ΦF = 0.12) upon UV irradiation.
关键词： polymer gels,fluorescence switching,photoisomerization,gel-to-sol transition,hydrogen bonding
更新于2025-09-04 15:30:14
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Performance and Reliability Improvement under High Current Densities in Black Phosphorus Transistors by Interface Engineering
摘要： Few-layer Black phosphorus (BP) has recently emerged as a promising two-dimensional (2D) material for electronic and optoelectronic devices due to its high mobility and tunable bandgap. However, BP is known to have quick degradation and oxidize in ambient conditions by breaking of the P-P bonds. As a result, there is a growing need to encapsulate BP that avoids oxygen and water while retaining the high electric performance of the devices. Here we demonstrate a hydrophobic polymer encapsulation technique with improved thermal conductivity for high current density, which preserves the electrical properties of BP back-gate transistors compared to the commonly used Al2O3 encapsulation with improved mobility and minimal traps. The on-off ratio increases for more than an order of magnitude at room temperature and more than four orders of magnitude at cryogenic temperatures. High field transport shows the first systematic study on unprecedented breakdown characteristics up to -5.5 V for the 0.16 μm transistors with a high current of 1.2 mA/μm at 20 K. These discoveries open up a new way to achieve high-performance 2D semiconductors with significantly improved breakdown voltage, on-off ratios, and stability under ambient conditions for practical applications in electronic and optoelectronic devices.
关键词： encapsulation,polymer,Black phosphorus,high-field transport,field-effect transistors,breakdown voltage,reliability
更新于2025-09-04 15:30:14
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Phase behavior of main-chain liquid crystalline polymer networks synthesized by alkyne–azide cycloaddition chemistry
摘要： Liquid crystalline polymer networks (LCNs) couple polymer chain organization to molecular ordering, the switching of which has been shown to impart stimuli-responsive properties, including actuation and one-way shape memory, to the networks. While LCNs have long been proposed as artificial muscles, recent reports have also suggested potential as dynamic biomaterial substrates. In contrast to many existing LCNs synthesized using hydrophobic spacers, this work investigates networks synthesized using more hydrophilic spacers to promote interaction with water. A challenge with such materials is liquid crystalline phases could be disrupted in hydrated networks. This work thus investigates the impact of polyether spacers and mesogen composition on the phase behavior of LCNs. Main-chain LCNs were synthesized using alkyne–azide cycloaddition ("click" chemistry), where two different mesogens (5yH and 5yMe) and a non-LC monomer (5yTe) were coupled with one of two different polyether spacers, poly(ethylene glycol) and poly(propylene glycol), and a crosslinker. The chemistry led to high gel fraction materials, the workup of which resulted in networks that displayed no difference in cellular toxicity due to leachable components compared to tissue culture plastic control. Calorimetric analysis, dynamic mechanical analysis, and X-ray scattering revealed the LC microstructure and temperature-responsive properties of the networks. The use of low molecular weight polyether spacers was found to prevent their crystallization within the LC network, and adjusting mesogen composition to enhance its LC phase stability allowed the use of spacers with larger molecular weights and pendant groups. Hydrated networks were found to rearrange their structure compared to dry networks, while maintaining their LC phases. Like other crosslinked LC materials, the networks display shape changes (actuation) that are tied to changes in LC ordering. The result is a new synthetic approach for polydomain networks that form stable LC phases that are tailorable using polyether spacers and may enable future application as hydrated, stimuli-responsive materials.
关键词： Liquid crystalline polymer networks,Phase behavior,Alkyne–azide cycloaddition,Stimuli-responsive materials,Polyether spacers
更新于2025-09-04 15:30:14