Zwitterion Interlocked Diarylethene Molecules Order, Unconnected Diarylethene Molecules Disorder.

A diarylethene-based zwitterionic molecule (DZM) is newly synthesized for the development of smart films exhibiting reversible color change and switchable ionic conductivity in response to external light stimuli. This dual molecular building block is constructed through zwitterionic interlocking and strong phase separation between the dendron-shaped aliphatic tails and the diarylethene head. Uniaxial shear coating and molecular self-assembly result in anisotropically oriented nanostructures, which are further solidified through photopolymerization.

Polarization-Dependent Thin Films with Biaxial Anisotropic Absorption Constructed by a Single Coating and Subsequent Topochemical Polymerization of Chromophores.

For the construction of hierarchical superstructures with biaxial anisotropic absorption, a newly synthesized diacetylene-functionalized bipyridinium is self-assembled to use an electron-accepting host for capturing and arranging guests. The formation of the donor-acceptor complex triggers an intermolecular charge transfer, leading to chromophore activation. Polarization-dependent multichroic thin films are prepared through a sequential process of single-coating, self-assembly, and topochemical polymerization of host-guest chromophores.

Switchable Optical Properties of Dyes and Nanoparticles in Electrowetting Devices.

The optical properties of light-absorbing materials in optical shutter devices are critical to the use of such platforms for optical applications. We demonstrate switchable optical properties of dyes and nanoparticles in liquid-based electrowetting-on-dielectric (EWOD) devices. Our work uses narrow-band-absorbing dyes and nanoparticles, which are appealing for spectral-filtering applications targeting specific wavelengths while maintaining device transparency at other wavelengths.

The Role of Dithiocarbamate Catalysts in the Diversification of Sulfur Speciation Towards Anionic Sulfur.

Recently, there has been growing interest in the implementation of various "catalysts" to further diversify the substrate scope for inverse vulcanization reactions. While there have been several proposals on the mechanism of how these catalysts work, the speciation of sulfur in these mixtures has remained elusive. As a key component to understanding when and if these catalysts are appropriate, we sought to elucidate the role of dithiocarbamate species in inverse vulcanization reactions by attempting to characterize the speciation of sulfur.

White light thermoplasmonic activated gold nanorod arrays enable the photo-thermal disinfection of medical tools from bacterial contamination.

The outspread of bacterial pathogens causing severe infections and spreading rapidly, especially among hospitalized patients, is worrying and represents a global public health issue. Current disinfection techniques are becoming insufficient to counteract the spread of these pathogens because they carry multiple antibiotic-resistance genes. For this reason, a constant need exists for new technological solutions that rely on physical methods rather than chemicals.

Recent Advances in Electro-Optic Response of Polymer-Stabilized Cholesteric Liquid Crystals.

Cholesteric liquid crystals (CLC) are molecules that can self-assemble into helicoidal superstructures exhibiting circularly polarized reflection. The facile self-assembly and resulting optical properties makes CLCs a promising technology for an array of industrial applications, including reflective displays, tunable mirror-less lasers, optical storage, tunable color filters, and smart windows. The helicoidal structure of CLC can be stabilized via in situ photopolymerization of liquid crystal monomers in a CLC mixture, resulting in polymer-stabilized CLCs (PSCLCs).

Tuning of optical properties and phase behavior of Nanomaterial-stabilized blue phase liquid crystals.

Hypothesis: Nanoparticles of various shapes and sizes can affect the optical properties and blue phase (BP) stabilization of BP liquid crystals (BPLCs). This is because nanoparticles, which are more compatible with the LC host, can be dispersed in both the double twist cylinder (DTC) and disclination defects in BPLCs.

Experiments: This study presents the first systematic study of the use of CdSe nanoparticles having various sizes and shapes (spheres, tetrapods and nanoplatelets) to stabilize BPLCs.

Photo-Crosslinkable Inorganic/Organic Sulfur Polymers.

Inverse vulcanization techniques are used to fabricate thermodynamically stable, sulfur polymers. Sulfur-based polymers exhibit higher refractive indices and improved transparency in the mid-wave infrared region compared with most organic polymers. Herein, the postsynthetic modification of sulfur polymers created via inverse vulcanization to generate novel, inorganic/organic photoresists is discussed.

When Chirophotonic Film Meets Wrinkles: Viewing Angle Independent Corrugated Photonic Crystal Paper.

Light manipulation strategies of nature have fascinated humans for centuries. In particular, structural colors are of considerable interest due to their ability to control the interaction between light and matter. Here, wrinkled photonic crystal papers (PCPs) are fabricated to demonstrate the consistent reflection of colors regardless of viewing angles.

Remote-controllable and encryptable smart glasses: a photoresponsive azobenzene molecular commander determines the molecular alignments of liquid crystal soldiers.

For the development of optically encryptable smart glass that can control the molecular alignment of liquid crystals (LCs), an azobenzene-based reactive molecule (ARM) capable of photoisomerization is newly designed and synthesized. Photo-triggered LC-commandable smart glasses are successfully constructed by the surface functionalization technique using 3-aminopropyltriethoxysilane (APTMS) coupling agent and an ARM. The surface functionalization with the ARM is verified by spectroscopic analysis and various observations including changes in the wettability and surface morphology.

Electro-optic characteristics of stabilized cholesteric liquid crystals with non-liquid crystalline polymer networks.

Extensive prior research has explored the stabilization of the CLC phase with polymer networks. These prior efforts have demonstrated both tunable and switchable electro-optic reconfiguration of the selective reflection of the CLC phase. Recently, we and other groups have detailed that polymer stabilization of the CLC phase with liquid crystalline monomers retains "structural" chirality (, the chiral phase templates the morphology of the achiral polymer network).

Effect of Amorphous Crosslinker on Phase Behavior and Electro-Optic Response of Polymer-Stabilized Blue Phase Liquid Crystals.

Blue phase liquid crystals (BPLCs) composed of double-twisted cholesteric helices are promising materials for use in next-generation displays, optical components, and photonics applications. However, BPLCs are only observed in a narrow temperature range of 0.5-3 °C and must be stabilized with a polymer network.

Tuning the electrowetting behavior of quantum dot nanofluids.

Hypothesis: The electrowetting behavior of droplets can be altered by the inclusion of salts, surfactants, or nanoparticles. We propose that varying the properties of cadmium selenide/zinc sulfide quantum dots will affect the electrowetting behavior of fluorescent nanofluids. Information gathered will allow for greater control of fluid properties when designing a colloidal system in an electrowetting environment.

Correlation of Structure with Crystalline to Amorphous Phase Transitions of 1,3,6-Substituted Fulvene-Derived Molecular Glasses.

An investigation into the crystalline to amorphous phase transitions of prepared 1,3,6-substituted pentafulvenes showed the expected reversible heated melt and cooling recrystallization in only a few examples. Systematic incorporation of bulky substituents at the 6-position of the fulvene ring led to the nonreversible thermal behavior, rendering phases that were locked into glassy, vitrified states. These molecular glasses produced physically translucent and amorphous features with glass transition temperatures in the range of 61-77 °C, comparable with high-strength plastics such as polyethylene terephthalate.

Electrowetting Behavior and Digital Microfluidic Applications of Fluorescent, Polymer-Encapsulated Quantum Dot Nanofluids.

Digital microfluidics is a liquid-handling technology capable of rapidly and autonomously controlling multiple discrete droplets across an array of electrodes and has seen continual growth in the fields of chemistry, biology, and optics. This technology is enabled by rapidly switching the wettability of a surface through the application of an electric field: a phenomenon known as electrowetting-on-dielectric. The results reported here elucidate the wetting behavior of fluorescent quantum dot nanofluids by varying the aqueous-solubilizing polymers, changing the size of the nanocrystals, and the addition of surfactants.

Synthesis of Elastomeric Liquid Crystalline Polymer Networks via Chain Transfer.

Materials capable of complex shape changes have broad reaching applications spanning biomimetic devices, componentless actuators, artificial muscles, and haptic displays. Liquid crystal elastomers (LCE) are a class of shape programmable materials which display anisotropic mechanical deformations in response external stimuli. This work details a synthetic strategy to quickly and efficiently prepare LCEs through the usage of chain transfer agents (CTA).

Blue-shifting tuning of the selective reflection of polymer stabilized cholesteric liquid crystals.

We report on electrically-induced, large magnitude (>300 nm), and reversible tuning of the selective reflection in polymer stabilized cholesteric liquid crystals (PSCLCs) prepared from negative dielectric anisotropy nematic liquid crystal hosts. The electrically-induced blue shift in the selective reflection of the PSCLCs is distinguished from our prior reports of bandwidth broadening and red-shifting tuning of the selective reflection in PSCLCs. The dominant factor in delineating the electro-optic response of the PSCLCs detailed here are the preparation conditions.

Improved Performance of Glucose Bioanodes Using Composites of (7,6) Single-Walled Carbon Nanotubes and a Ferrocene-LPEI Redox Polymer.

The effect of incorporating different types of carbon nanotubes into composite films of a redox polymer (FcMe-C-LPEI) and glucose oxidase (GOX) was investigated. The composite films were constructed by first forming a high-surface area network film of either single-walled carbon nanotubes (SWNTs) or multiwalled carbon nanotubes (MWNTs) on a glassy carbon electrode (GCE) by solution casting of a suspension of Triton-X-100 dispersed SWNTs. Next a glucose responsive redox hydrogel was formed on top of the nanotube-modified electrode by cross-linking FcMe-C-LPEI with glucose oxidase via ethylene glycol diglycidyl ether (EGDGE).

Pixelated Polymers: Directed Self Assembly of Liquid Crystalline Polymer Networks.

Polymeric materials are pervasive in modern society, in part attributable to the diverse range of properties that are accessible in these materials. Polymers can be stiff or soft, dissipative or elastic, adhesive or nonstick. Localizing the properties of polymeric materials can be achieved by a number of methods, including self-assembly, lithography, or 3-d printing.

Synthesis, Electrochemical Characterization, and Linear Free Energy Relationship of 1,3-Diphenyl-6-alkyl/arylfulvenes.

A series of 1,3-diphenyl-6-alkyl/arylfulvenes was prepared, and the electrochemical properties were investigated. The addition of phenyl groups about the fulvene raised the reduction potential and helped to stabilize the electrochemically generated radical anion. The addition of various functional groups onto the phenyl ring at the 6-position of 1,3,6-triphenylfulvene results in a linear free energy relationship between reduction potential and the Hammett substituent constant, σ.

Electrochemical Characterization of Layer-By-Layer Assembled Ferrocene-Modified Linear Poly(ethylenimine)/Enzyme Bioanodes for Glucose Sensor and Biofuel Cell Applications.

Ferrocenylhexyl- and ferrocenylpropyl-modified linear poly(ethylenimine) (Fc-C6-LPEI, Fc-C3-LPEI) were used with periodate-modified glucose oxidase (p-GOX) in the layer-by-layer assembly of enzymatic bioanodes on gold. Fc-C6-LPEI/p-GOX and Fc-C3-LPEI/p-GOX films of 16 bilayers were capable of generating up to 381 ± 3 and 1417 ± 63 μA cm(-2), respectively, in response to glucose. These responses are greater than those of analogous bioanodes fabricated using conventional cross-linking techniques and are extremely high for planar, low surface area, single-enzyme electrodes.

First preparation of low band gap fulvene-modified polynorbornene via ring-opening metathesis polymerization.

New polymers containing intact pendant-fulvene moieties have been successfully prepared from 1,3-phenyl-6-norbornenylfulvene via ring-opening metathesis polymerization (ROMP). The prepared polyfulvenes have unique electrochemical and photophysical properties which make them interesting candidates for light harvesting materials.