Photonic metal-polymer resin nanocomposites with chiral nematic order.

Mesoporous resins with chiral nematic order were used as scaffolds to construct novel iridescent metal-polymer composites. Gold, silver and palladium nanoparticles were formed by an in situ reduction reaction. We have investigated the effects of concentration and time on the deposition.

Polymer and Carbon Spheres with an Embedded Shell of Plasmonic Gold Nanoparticles.

Gold nanoparticle (AuNP)/resin nanosphere composites have been prepared in a novel process where the resin functions as both the host and reducing agent. Electron tomography showed that the AuNPs are organized into a concentric shell fully embedded in the resin nanospheres. Pyrolysis of the composite spheres afforded microporous N-doped carbon nanospheres with a pseudoshell of embedded AuNPs.

Photonic patterns printed in chiral nematic mesoporous resins.

Chiral nematic mesoporous phenol-formaldehyde resins, which were prepared using cellulose nanocrystals as a template, can be used as a substrate to produce latent photonic images. These resins undergo swelling, which changes their reflected color. By writing on the films with chemical inks, the density of methylol groups in the resin changes, subsequently affecting their degree of swelling and, consequently, their color.

Functional materials from cellulose-derived liquid-crystal templates.

Cellulose nanocrystals (CNCs), known for more than 50 years, have attracted attention because of their unique properties such as high specific strength and modulus, high surface area, and fascinating optical properties. Just recently, however, their potential in supramolecular templating was identified by making use of their self-assembly behavior in aqueous dispersions in the presence of compatible precursors. The combination of the mesoporosity, photonic properties, and chiral nematic order of the materials, which are available as freestanding films, has led to a significant number of interesting and promising discoveries towards new functional materials.

Responsive mesoporous photonic cellulose films by supramolecular cotemplating.

Cellulose-based materials have been and continue to be exceptionally important for humankind. Considering the bioavailability and societal relevance of cellulose, turning this renewable resource into an active material is a vital step towards sustainability. Herein we report a new form of cellulose-derived material that combines tunable photonic properties with a unique mesoporous structure resulting from a new supramolecular cotemplating method.

Tunable mesoporous bilayer photonic resins with chiral nematic structures and actuator properties.

Chiral nematic structures with different helical pitch from layer to layer are embedded into phenol-formaldehyde bilayer resin composite films using cellulose nanocrystals (CNCs) as templates. Selective removal of CNCs results in mesoporous resins with different pore size and helical pitch between the layers. Consequently, these materials exhibit photonic properties by selectively reflecting lights of two different wavelengths and concomitant actuation properties.

Imprinting of Photonic Patterns with Thermosetting Amino-Formaldehyde-Cellulose Composites.

A family of new amino resin-cellulose nanocrystal composites is reported. Owing to the chiral nematic order of the cellulose nanocrystals (CNCs) embedded in the amino resin polymer, the materials appear highly iridescent and their color can be controlled by the addition of salt. The freshly prepared samples are highly flexible and their color can be manipulated by applying pressure to the films.

Effects of spacer length and terminal group on the crystallization and morphology of biscarbamates: a longer spacer does not reduce the melting temperature.

The effects of alkyl side chain and spacer lengths and the type of terminal group on the morphology and crystallization of a homologous series of biscarbamates (model compounds for polyurethanes) were investigated. Biscarbamates were synthesized with alkyl side chains of various lengths ranging from C4 to C18 and an alkyl spacer group with 12 CH2 units (C12 spacer) between the two hydrogen bonding motifs. The crystallization and morphological features are compared with the previously studied biscarbamates with a C6 spacer.

Effects of carbon atom parity and alkyl side chain length on the crystallization and morphology of biscarbamates, a set of model compounds for polyurethanes.

Solid state morphology and crystallization behavior of a homologous series of biscarbamate molecules having varying alkyl side chain lengths with different carbon atom parity were investigated. These are model compounds for polyurethanes. We synthesized a set of biscarbamates with double hydrogen bonding motifs separated by a (CH(2))(6) spacer and with alkyl side chains of various lengths ranging from C(3) to C(18) at the ends.

Encapsulation of dye molecules and nanoparticles in hollow organogel fibers of a nonchiral polyurethane model compound.

We present the case of a nonchiral organogelator that forms hollow fibers and encapsulates silver nanoparticles (SNP) and a dye molecule. The biscarbamate molecule (a model compound for polyurethanes), which has two hydrogen-bonding motifs symmetrically attached to n-dodecyl side chains (C(12)), gels benzonitrile with hollow fibrillar morphology. The C(12) molecules form sheets that eventually wrap into hollow fibers to form the gel network.

Influence of double hydrogen bonds and alkyl chains on the gelation of nonchiral polyurethane model compounds: sheets, eaves trough, tubes and oriented fibers.

We describe the gelation, upon self-assembly of a series of nonchiral molecules, resulting in tubular morphology of the fibers. These are biscarbamates, which are model compounds for polyurethanes with two hydrogen bonding groups separated by a (CH(2))(6) spacer and symmetrically substituted with alkyl chains on either side varying in length from C(6) to C(18). Upon gelation, these molecules form a sheet initially.

Carbon nanotube reinforced porous gels of poly(methyl methacrylate) with nonsolvents as porogens.

We fabricated porous organogels of poly(methyl methacrylate) (PMMA) using nonsolvents as porogens. In contrast to the use of inorganic materials, surfactants, etc., as porogens, we used the nonsolvents for PMMA such as water, methanol, propanol, and cyclohexane.

Molecular selectivity and immiscibility during the crystallization of mixtures of a set of homologous self-assembling molecules.

Utilizing self-assembly to create supramolecular structures is an active area at this time. Hybrid materials created by blending or doping, e.g.