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In this article, we describe the synthesis and self-assembly of novel Janus bottlebrushes with cellulose as a polymeric backbone. The cellulosic Janus bottlebrushes, bearing poly(e-caprolactone) (PCL) and polystyrene (PS) branches at the C-2,3 and C-6 positions of anhydroglucose units, respectively, were successfully prepared using a bulky p-methoxytrityl protecting group and by combining the “grafting-from” ring-opening polymerization of e-caprolactone with the “grafting-to” click chemistry of PS. The degree of substitution of PCL at the C-2,3 positions was estimated to be 1.5, whereas values of 0.64–0.84 were estimated for the C-6 position of PSs with different molecular weights (number-average molecular weight = 4.0, 9.2, or 16 kg mol−1), depending on the length of the PS graft. The Janus bottlebrushes (PS/PCL = 50:50 v/v) self-assembled to form a lamellar microdomain structure comprising three layers (amorphous PCL, crystalline PCL, and amorphous PS layers), as characterized by small-angle X-ray scattering and transmission electron microscopy. The interlamellar distance was approximately 30 nm, depending on the length of the PS graft. The results illustrate that cellulosic polymeric backbones for Janus bottlebrushes can exhibit microscale morphologies, potentially leading to the development of polymers with new morphologies and functionalities.

Lithium-excess layered positive electrodes containing Fe and Ni are promising materials for the next generation of high voltage lithium ion batteries (LIB) because they are more chemically stable t...

Very-thick, concentrated brushes of poly(methyl methacrylate) (PMMA) were synthesized by surface-initiated atom transfer radical polymerization in N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bi...

Fullerene-containing polymers offer the unique opportunity to fabricate self-assembled nanostructures and organic electronics. The synthesis of well-defined fullerene-containing polymers, having double polymeric chains attached to fullerene in a regioselective manner, is a fundamental challenge in both synthetic organic chemistry and precision polymer chemistry. Here, inspired by the state-of-the-art fullerene chemistry, we present a new strategy for the stepwise synthesis of double-armed polymers with fullerene C60 at the junction in high reaction yields and with high selectivity. First, poly(styrene)-attached 1,2-hydrofullerene (1,2-PS-C60-H) was synthesized via the cobalt-catalyzed radical addition reaction. Next, the fullerenyl anion, 1,2-PS-C60−, was reacted with bromo-terminated poly(acetoxystyrene) to generate diblock copolymer 1,4-bisadducts (1,4-PS-C60-PAS). This example highlights the applicability of polymeric 1,4-fullerene bisadducts for self-assembling building blocks and potential organic electronics.

The synthesis of ultrathick concentrated poly(methyl methacrylate) (PMMA) brushes by atom transfer radical polymerization (ATRP) was investigated. The reactions were performed with a catalyst syste...

In this article, we describe the conformational characteristics of a cellulosic bottlebrush, i.e., a cellulose derivative of densely substituted side chains, in a dilute solution in order to clarif...

Recently, concentrated polymer brushes (CPBs) have attracted much attention as potential tribomaterials showing an ultralow friction coefficient (e.g., 10−4 in a microtribological analysis)...

The degree of chain-end functionality in a densely grafted, concentrated polymer brush is a critical parameter. In this study, p-polarized multiple-angle incidence resolution spectrometry (pMAIRS) ...

Bacterial cellulose (BC) has a well-defined nanofiber network in the gel, potentially applicable as a reinforcement filler for ideal polymer composite materials. In this study, BC/poly(methyl metha...

Concentrated polymer brushes (CPBs) are promising soft-material coatings for improving tribological properties under severe sliding conditions, even in the macroscopic scale. Therefore, they are expected to be applied to mechanical sliding components. However, the durability of CPBs has remained challenging for industrial applications. Previous studies revealed that applying a groove texture to the CPB substrate is effective in improving the durability of CPBs. In order to achieve further improvement of durability of CPBs, we attempted to apply nano-periodic structures, whereas the groove texture applied in previous studies has widths and depths in micrometres. In this study, the effect of the nano-periodic structure in addition to the groove texture applied to the CPB substrate on the durability of CPB is investigated. The results demonstrate a significant improvement in the durability of CPBs by up to 90% compared with non-textured CPB when an appropriate nano-periodic structure is applied (i.e. a nano-periodic structure oriented parallel to the groove texture).

Concentrated polymer brushes (CPBs) are known to suppress biofouling phenomena, such as protein adsorption and cell adhesion. However, a cumbersome process is needed for their synthesis. Here, we report a simple and versatile method for fabricating nonbiofouling coatings that uses well-defined bottlebrushes instead of CPBs. First, a macroinitiator, poly[2-(2-bromoisobutyryloxy)ethyl methacrylate] (PBIEM), was synthesized by reversible addition-fragmentation chain transfer polymerization. Then, poly[poly(ethylene glycol) methyl ether methacrylate] was grafted from PBIEM through atom transfer radical polymerization to form well-defined bottlebrushes. By controlling the graft chain length, two types of bottlebrushes could be prepared, namely those with a semi-dilute polymer brush (SDPB) structure or a CPB structure on the surface of the outermost layer. Crosslinked films of the bottlebrushes were prepared on silicon wafers by spin-coating and subsequent radical coupling. Importantly, the CPB-type bottlebrush films showed significantly better nonbiofouling characteristics than those of the SDPB-type bottlebrush films.

Production of nanocomposites from macro-scale materials in situ in a melting compounder is highly desirable yet challenging. In this study, we develop a highly efficient approach for the preparation of cellulose nanofiber (CNF)-reinforced high-density polyethylene (HDPE) composite materials from as-received wood pulp fibers, in which nanofibrillation-assisting plasticizers (urea and urea derivatives) and a diblock copolymer dispersant are used. The most effective plasticizer is urea, which plays a crucial role in producing CNF with less fragmentation during the kneading step, owing to the plasticization/nanofibrillation and the reaction with hydroxyl groups of cellulose fibers into a carbamate. The diblock copolymer as a dispersant enables the stabilization of the appropriate dispersion of the produced CNF in nonpolar HDPE. The resulting composites exhibit significantly improved mechanical properties, including a 6.9-fold increase in the Young’s modulus with 10 wt % loading of wood pulp fibers over that o...

A new type of three-dimensional cell culture using a cellulose nanofiber modified with a concentrated polymer brush (CNF-CPB) is described from the viewpoint of colloidal flocculation. By varying the CNF-CPB concentrations from 0.005 to 0.5 wt %, we demonstrate that hepatocyte cells self-assemble with the CNF-CPBs and change the floc size and shape (fully filled or hollow) in a concentration-dependent manner. A protein adsorption test indicates that affinity interaction between the proteins (cells) and CPB is critical for cellular flocculation. In addition, gene expression analysis confirms that the cellular flocs using CNF-CPBs enhance cell functions compared to CNFs with semidilute polymer brushes and pristine CNFs.

In this article, the conservation of archaeological waterlogged wood (WW) of Afzelia sp. (medium degraded: Umax = 385%) was impregnated in vacuum with an aqueous solution of acrylic acid (AA), sodium acrylate monomer (AANa), crosslinking agent (MBA) and catalyst (V-501). The simultaneous in situ polymerization and crosslinking resulted in slightly crosslinked sodium polyacrylate (PAANa) in the wood structure. The results showed that untreated WW had only a very limited ability to re-swell to recover its original dimensions from a collapsed condition, while WW protected by crosslinked PAANa could almost fully recover its original shape and size even after several drying–rewetting cycles. From microscopic observations, treated wood was found to maintain its original cell structure, form and shape even after repeated drying–rewetting cycles. PAANa was observed to be densely localized near the middle lamella, the cell corners, and the cell lumina by transmission electron microscopy observation. These observations suggest that our PAANa treatment provides reasonable strength as well as favorable hydrophilicity to avoid hornification of the cell wall upon drying, thus providing unique shape recovery properties.

Cellulose nanofibers (CNFs) hold great potential as sustainable reinforcement fillers with excellent mechanical, thermal, and chemical properties. However, in polyolefin nanocomposite materials, the rational control of dispersion and the improvement of interfacial strength remain challenging. Herein we propose the tuning of the interface between CNF and high-density polyethylene by the design of polymer dispersants on the basis of surface free energy and the glass transition temperature. The former is related to the wettability against the polymer matrix and is therefore critical to the dispersion of CNF whereas the latter is related to the interfacial strength between CNF and HDPE. As a result of this investigation, we discovered a suitable dispersant for CNFs, poly(dicyclopentenyloxyethyl methacrylate)-block-poly(2-hydroxyethyl methacrylate), which played a pivotal role in achieving both a uniform dispersion of CNF and greatly improved mechanical properties, including a 4-fold increase of the Young's modulus over that of neat HDPE with 10 wt % CNF loading.

Halogen exchange of alkyl bromide (R–Br) with sodium iodide (NaI) was used for the transformation of R–Br to alkyl iodide (R–I) in situ in organocatalyzed living radical polymerization (LRP). R–Br was employed as a starting compound (precursor), and the R–I formed in situ was employed as an initiating dormant species for the polymerization. The efficiency of the transformation significantly depends on the R group of R–Br. By the rational selection of the R group and reaction temperature along with the use of tetrabutylammonium iodide (Bu4NI) as a catalyst, low-polydispersity (Mw/Mn = 1.1–1.4) polymers were obtained with high conversions (e.g., 70–90%) in reasonably short periods of time (typically 3–10 h) in the polymerizations of methyl methacrylate, butyl acrylate, styrene, acrylonitrile, and functional methacrylates. Well-defined diblock and triblock copolymers and a chain-end functional polymer were also obtained. R–Br is generally much more stable than R–I upon storage. Various R–Br are commercially available. The use of simple, stable, and inexpensive R–Br as precursors of the dormant species is an attractive feature of this system. The high monomer versatility and the accessibility to a wide range of polymer structural designs demonstrated in this work show the capability of this system for use in a range of applications. Accepted version

In this article, we propose a versatile method to prepare epoxy resin-based monolith membrane without any surface skin layer through polymerization induced spinodal type phase separation using a poly(vinyl alcohol) sacrificial film, where the monolith is a porous material with a bicontinuous skeletal structure. The resulting monolith membranes exhibit well-defined pore sizes, and high mechanical strength, thermal stability, and ionic conductivity in liquid electrolytes. A block copolymer has been applied to control the pore size to be at the mesoscale, and surface skinless freestanding monolith membrane have been developed. To improve the mechanical properties, cellulose nanofibers are introduced as a reinforcing filler. The monolith membranes are thermally resistant at least up to 200 °C. The ionic conductivity of the monolith membranes (0.71 mS cm−1 at 25 °C) is comparable to those of commonly used polyolefin separators. The results that are presented here demonstrate that polymer monolith membranes have bright prospects as novel separators for lithium ion batteries, fuel cells, etc.

Various Langmuir–Blodgett (LB) films of tetraphenylporphyrin (TPP)-bound acyl celluloses with different degrees of substitution of the TPP groups (DSTPP) and different acyl groups were prepared. TPP-bound acyl celluloses with DSTPP values less than 0.38 and myristoyl groups as the O-2 and O-3 substituents were suitable for obtaining LB mono-layer films with high quantum yields. The horizontal lifting method was better than the vertical dipping method for the deposition of LB films. The number of layers in LB multi-layer films of TPP-bound myristoyl cellulose with a DSTPP of 0.36 also influenced the quantum yield, and the quantum yield of the LB di-layer film was higher than those of the LB mono- and tri-layer films. This information will be useful in the improvement of the photocurrent generation performances of LB films of TPP-bound acyl celluloses.

An effective approach for the dispersion of hydrophilic cellulose nanofiber (CNF) in hydrophobic high-density polyethylene (HDPE) is presented using adsorption of a diblock copolymer dispersant. The dispersant consists of both resin compatible poly(lauryl methacrylate) (PLMA) and cellulose interactive poly(2-hydroxyethyl methacrylate) blocks. The PLMA-adsorbed CNFs are characterized by FT-IR and contact angle measurement, revealing successful hydrophobization. X-ray CT imaging shows there are apparently less CNF aggregates in the nanocomposites if adding amount of the dispersant was enough. The good dispersion results in a high mechanical reinforcement, corresponding to 140% higher Young's modulus and 84% higher tensile strength than the neat HDPE. This approach is broadly applicable and allows for easy manufacturing process for strong and lightweight CNF-reinforced nanocomposite materials.

We developed a novel and practical assessment technique for endoglucanase (EG) activity by measuring the degree of polymerization (DP) of cellulose from Eucalyptus globulus. This evaluation method demonstrated that EG II from Trichoderma reesei had higher endoglucanase activity than EG I, which has not been detected in conventional experiments using carboxymethyl cellulose as a model substrate. In addition, a high-throughput protocol for DP measurement was developed by using near-infrared spectroscopy combined with a multivariate analysis. Interpreting the regression coefficient, a reciprocal correlation was observed between the relative crystallinity of the cellulosic residue after enzymatic hydrolysis and the DP.

Photocontrolled surface-initiated reversible complexation mediated polymerization (photo-SI-RCMP) was successfully applied to fabricate concentrated polymer brushes with complex patterning structures. Positive-type patterned polymer brushes were obtained by photo-SI-RCMP under visible light (550(±50) nm) using photomasks. A particularly interesting finding was that negative-type patterned polymer brushes were also obtainable in a facile manner. A nonspecial UV light (250-385 nm) enabled the preparation of pre-patterned initiator surfaces in a remarkably short time (1 min), leading to negative-type patterned polymer brushes. Based on this unique selectivity between visible and UV light, the combination of two patterning techniques enabled the preparation of complex patterned brushes, including diblock copolymers, binary polymers, and functional binary polymers, without multistep immobilization of one or more initiators on the surfaces.

Charged substrates are expected to promote cell adhesion via electrostatic interaction, but it remains unclear how cells adhere to these substrates. Here, initial cell adhesion (30 min) was re-examined on charged substrates in serum-containing and serum-free media to distinguish among various cell adhesion mechanisms (i.e., electrostatic interaction, hydrophobic interaction, and biological interaction). Cationic and anionic methacrylate copolymers were coated on nonionic nontissue culture-treated polystyrene to create charged substrates. Cells adhered similarly on cationic, anionic, and nonionic substrates in serum-free medium via integrin-independent mechanisms, but their adhesion forces differed (anioniccationicnonionic substrates), indicating that cell adhesion is not mediated solely by the cells' negative charge. In serum-containing medium, the cells adhered minimally on anionic and nonionic substrates, but they adhered abundantly on cationic substrates via both integrin-dependent and -independent mechanisms. These results suggest that neither electrostatic force nor protein adsorption is accountable for cell adhesion. Conclusively, the observed phenomena revealed a gap in the generally accepted understanding of cell adhesion mechanisms on charged polymeric substrates. A reanalysis of their mechanisms is necessary.

A series of novel mono- and bis[(9-alkylcarbazol-3-yl)methyl]acrylamides were synthesized and their radical polymerization was investigated. Emissions of bis(carbazolyl)acrylamide polymers were ext...

In this study, a one-side zero-azimuth anchoring in-plane switching (OZ-IPS) liquid crystal display (LCD) employing poly(n-hexyl methacrylate) (PHMA) bottlebrush polymers as an application-type zero-azimuth anchoring material was successfully developed. The twist anchoring coefficient A 2 measured for the nematic liquid crystal (NLC) on the PHMA bottlebrush at 25??C was comparable to that of the same NLC on high-density PHMA brushes. Optimizing the optical design increased the transmission efficiency (TE) of the OZ-IPS cell with the negative NLC to 95%, which was significantly higher than that of conventional IPS cells. Using optical simulation, the OZ-IPS LCDs with a negative NLC clearly exhibited the highest TE (107% of TN LCDs) for LCDs developed thus far. Moreover, the higher transmittance of the OZ-IPS LCDs was also confirmed for the practical TFT LCD, which exhibited a maximum luminance that was 30% higher than conventional IPS TFT LCDs.

In this article, we propose a novel methodology for the formation of monodisperse regularly sized disks of several nanometer thickness and with diameters of less than 100 nm using Langmuir monolayers as fabrication media. An amphiphilic triimide, tri-n-dodecylmellitic triimide (1), was spread as a monolayer at the air-water interface with a water-soluble macrocyclic oligoamine, 1,4,7,10-tetraazacyclododecane (cyclen), in the subphase. The imide moieties of 1 act as hydrogen bond acceptors and can interact weakly with the secondary amine moieties of cyclen as hydrogen bond donors. The monolayer behavior of 1 was investigated through π-A isotherm measurements and Brewster angle microscopy (BAM). The presence of cyclen in the subphase significantly shifted isotherms and induced the formation of starfish-like microstructures. Transferred monolayers on solid supports were analyzed by reflection absorption FT-IR (FT-IR-RAS) spectroscopy and atomic force microscopy (AFM). The Langmuir monolayer transferred onto freshly cleaved mica by a surface touching (i.e., Langmuir-Schaefer) method contained disk-shaped objects with a defined height of ca. 3 nm and tunable diameter in the tens of nanometers range. Several structural parameters such as the disk height, molecular aggregation numbers in disk units, and 2D disk density per unit surface area are further discussed on the basis of AFM observations together with aggregate structure estimation and thermodynamic calculations. It should be emphasized that these well-defined structures are produced through simple routine procedures such as solution spreading, mechanical compression, and touching a substrate at the surface. The controlled formation of defined nanostructures through easy macroscopic processes should lead to unique approaches for economical, energy-efficient nanofabrication.

6-Azafulleroid-6-deoxy-2,3-di- O -myristoylcellulose ( 3 ) was synthesized from 6-azido-6-deoxycellulose ( 1 ) by two reaction steps. The myristoylation of compound 1 with myristoyl chloride/pyridine proceeded smoothly to give 6-azido-6-deoxy-2,3-di- O -myristoylcellulose ( 2 ) in 97.0% yield. The reaction of compound 2 with fullerene (C 60 ) was carried out by microwave heating to afford compound 3 in high yield. It was found from FT-IR, 13 C NMR, UV–vis, differential pulse voltammetry (DPV), SEC analyses that compound 3 was the expected C 60 -containing polymer. Consequently, maximum degree of substitution of C 60 (DS C60 ) of compound 3 was 0.33.

Conjugated polymers gain growing importance as conductive materials in industrial applications in various fields of electronic devices. Cellulose with its extraordinary supramolecular structure and material properties can help to awake the possibilities for conducting polymers in interplay of the two materials. The ability of additional derivatization, the stiff and oriented molecular structure and the inherent strength, stability and film-forming properties give cellulose a complementary role to the brittle conjugated polymers, cellulose imparting the features of a stable and robust carrier component. To go forward this way, making a composite out of cellulose and conducting polymers is a prerequisite. Different strategies to form composite materials of non-derivatized cellulose and conductive organic polymers were tested. Significant differences between various mixing strategies as well as between the conducting polymers polyaniline (PAni), polypyrrole (PPy), and polythiophen (PTh) were observed. In situ synthesis of the conducting polymers in cellulose solutions and microcellulose dispersions as well as blending of pre-synthesized conducting polymers in these cellulose systems were tested. Unexpectedly, not homogenous mixtures showed best results in respect to film formation and conductivity, but composites formed by heterogeneous mixtures of the conducting polymers within a cellulose gel. Best results were obtained with finely dispersed PAni. The results support development studies towards circuitry and photo-current systems based on cellulose carriers.

Nanotechnology from a bottom-up approach relies heavily on supramolecular chemistry that can potentially provide nano- and microstructures with molecular level precision of internal configurations through low-energy spontaneous processes. Moreover, supramolecular assemblies at the two-dimensional interface have great potential to be integrated into artificial devices. Studies on supramolecular chemistry at interfaces are, therefore, highly relevant for the development of nanotechnology. Another distinct aspect of supermolecules exists in their advanced dynamic properties that are anticipated to provide various stimuli-responsive systems. Here, we summarise the recent literature describing the dynamic behaviours of supermolecules at interfaces and supramolecular chemistry at dynamic interfaces categorised into three classes: (i) dynamic behaviour at solid surfaces, (ii) supermolecules at dynamic interfaces in liquid media and (iii) supermolecules at the air–water interface.

In order to elucidate the characteristic features of commercial methylcellulose precisely, O-methylcellulose model copolymers consisting of 2,3,6-tri-O-methylanhydroglucose unit (236MeAGU) and 2-O-methylanhydroglucose unit (2MeAGU) with various composition ratios were synthesized via cationic ring-opening copolymerization of the corresponding glucose orthoester derivatives, subsequent removal of pivaloyl and allyl groups, and methylation. The structure of the obtained copolymers was confirmed by 1H-, 13C-NMR, and FT-IR. Temperature-dependent turbidity measurement verified their thermoresponsive behavior in aqueous solution. The lower critical solution temperature was tuned from 63 to 45 °C above 47 mol-% 236MeAGU content. The hydrophobicity along the cellulose chain was dominant to determine their physical properties. However, the aqueous properties of the MC model copolymers were strongly affected by the slight difference of the composition ratio. The present method would provide further details of the structure–property relationship of O-methylcellulose.

Role-sharing functionalized cellulose derivatives having Mg, Zn, Cu, and Pd porphyrins are used for photocurrent generation system fabricated by the LB technique, mimicking the array of natural photosynthetic light-harvesting systems. These polymers exhibited different absorption and redox properties in solution depending on the central metal ions. On visible light illumination, the LB film generated anodic photocurrent in the order of Pd > free base > Zn > Cu > Mg. By inserting Pd ion, using myristoyl group, and adjusting the DS, the photocurrent quantum yield was 6.9 times as great as that of conventional porphyrin cellulose. These findings may provide opportunities for the design of a new class of organic solar cells, based on cellulose molecular characteristics.

Using ultra-small angle X-ray scattering (USAXS), we analyzed the higher-order structures of nanoparticles with a concentrated brush of an ionic liquid (IL)-type polymer (concentrated-polymer-brush-modified silica particle; PSiP) in an IL and the structure of the swollen shell layer of PSiP. Homogeneous mixtures of PSiP and IL were successfully prepared by the solvent-casting method involving the slow evaporation of a volatile solvent, which enabled a systematic study over an exceptionally wide range of compositions. Different diffraction patterns as a function of PSiP concentration were observed in the USAXS images of the mixtures. At suitably low PSiP concentrations, the USAXS intensity profile was analyzed using the Percus-Yevick model by matching the contrast between the shell layer and IL, and the swollen structure of the shell and "effective diameter" of the PSiP were evaluated. This result confirms that under sufficiently low pressures below and near the liquid/crystal-threshold concentration, the studied PSiP can be well described using the "hard sphere" model in colloidal science. Above the threshold concentration, the PSiP forms higher-order structures. The analysis of diffraction patterns revealed structural changes from disorder to random hexagonal-closed-packing and then face-centered-cubic as the PSiP concentration increased. These results are discussed in terms of thermodynamically stable "hard" and/or "semi-soft" colloidal crystals, wherein the swollen layer of the concentrated polymer brush and its structure play an important role.

Thin films consisting of 6-O-porphyrin-2,3-di-O-stearoylcellulose (H 2 PCS) and fullerene (C 60 ) were fabricated for anodic photocurrent generation systems by the Langmuir-Blodgett (LB) technique. The π-complexation between the porphyrin moiety and C 60 in the LB films was investigated by means of the surface pressure (π)-area (A) isotherms, UV-vis, and fluorescence spectroscopy. The photocurrent density generated from the H 2 PCS-C 60 LB monolayer films exhibited an increase with increasing the C 60 proportion and reached a maximum at a mixing ratio of 1:2, yielding a quantum yield of 12.5% and an IPCE (incident photon-to-current efficiency) of 0.50% at a bias potential of +100 mV vs. SCE. Furthermore, the LB five-layer films could give rise to the IPCE value of 1.5% at +100 mV without significant decline of the quantum yields, which was due to the function of C 60 as an electron carrier to improve the interlayer electron transfer through each layer. These results have demonstrated a promising method for preparing the donor-acceptor systems using cellulose as a scaffold in the LB films.

Langmuir-Blodgett (LB) films containing porphyrin molecules were fabricated by use of 6-O-dihydrophytylcellulose (DHPC) toward anodic photocurrent generation systems. To suppress the porphyrin aggregation, two different approaches were applied: (1) mixing a low-molecular-weight porphyrin having a diterpenoid carbon skeleton (DPor) with DHPC as a matrix (matrix fabrication) and (2) bonding porphyrin molecules to the hydroxyl groups of DHPC covalently, converting into 6-O-dihydrophytyl-2,3-di-O-[p-(10,15,20-triphenyl-5-porphyrinyl)-benzoyl]cellulose as a scaffold (scaffold fabrication). The structure and film properties of the monolayers and the LB films were investigated by the surface pressure (π)–area (A) isotherm measurements, atomic force microscopy, UV–Vis spectroscopy, and absorption dichroism measurements. The porphyrin aggregation in the LB film could be well suppressed only by the scaffold fabrication, leading to the improvement of the photocurrent quantum yields. The efficient photocurrent performance can be demonstrated by the isolation and the parallel orientation of porphyrin moieties due to the cellulose rigid scaffold.

Langmuir-Blodgett films of a cellulose derivative containing porphyrins, porphyrin-cellulose, were fabricated in order to construct a cellulose-based molecular photocurrent generation system. On visible light illumination of the LB monolayer film deposited on an ITO electrode, anodic photocurrents were observed with a quantum yield of 1.6% at an applied potential of 0 V versus SCE, and 3.8-4.6% at 0.2-0.3 V versus SCE. These values indicate that the self-quenching of the photoexcited porphyrins in the cellulose LB film was suppressed, while porphyrin moieties in the LB film had a densely packed structure. This is because the porphyrins are located at a distance of approximately 1.0 nm along the cellulose backbone.

Redox-active Langmuir-Blodgett (LB) films containing dihydrophytyl ferrocenoate (DFc) and beta-carotene (betaC) were fabricated by use of 6-O-dihydrophytylcellulose (DHPC) as a matrix. A mixture of DFc-DHPC formed a stable monolayer. Atomic force microscopy images revealed that the DFc molecules were dispersed uniformly throughout the surface in the ratio DFc:DHPC = 2:8 at 30 mN m-1. The DFc-DHPC monolayer was transferred successfully onto a substrate, yielding Y-type LB films. Cyclic voltammograms for the DFc-DHPC LB films on an indium tin oxide (ITO) electrode exhibited a well-defined surface wave. The voltammograms of the DFc-DHPC LB films exhibited 60-40% redox-active ferrocene moieties, whereas those of the DFc-DHPC-betaC LB films exhibited 90-70%. X-ray diffraction patterns indicated that the distance between layers was independent of betaC molecules incorporated into the LB films. Consequently, these results suggested that betaC can function as a molecular wire.

Nanodisks with uniform height and tunable diameter on the nanometer scale were constructed without any lithographic processes. The disks consisting of an amphiphilic triimide module were formed at ...

Methyl xylopyranoside containing three 4-(pyrene-1-yl)benzoyl groups (PyXy) undergoes conformational interchange within a Langmuir monolayer upon mechanical compression. This xylose-type molecular machine PyXy was immobilized within two different matrix lipids, methyl stearate and methyl 2,3,4-tri-O-stearoyl-β-D-xylopyranoside, which respectively form rigid and soft monolayers. Structural properties of the monolayer were characterized by assessing the compressibility, compression modulus, and ideal limiting molecular area of PyXy, all of which were estimated from the π-A isotherm measurements. Only the rigid monolayer exhibited a transition to the condensed phase with a limiting molecular area of PyXy smaller than that of the cross-sectional area of the xylopyranose ring in its C1 chair conformation. This suggests conformational interchange of PyXy from the most stable (4)C1 (C1) form to the metastable (1)C4 (1C) form. Surface-reflective fluorescence spectroscopy of the monolayer was applied to detect excimer emission resulting from the face-to-face dimerization of pyrenes attached at the O-2 and O-4 positions of xylose. Fluorescence intensity of the excimer increased abruptly in the condensed region only when the rigid monolayer was applied. These results indicate that the rigidity of the matrix monolayer is a critical aspect of the precise manipulation of molecular machines at interfaces. Consequently, this study demonstrates that including a molecular machine into a rigid lipid matrix is a promising means for the preparation of a novel nanoassembly with dynamic functionalities variable depending on a mechanical stimulus.

In contrast to the success in artificial DNA- and peptide-based nanostructures, the ability of polysaccharides to self-assemble into one-, two-, and three-dimensional nanostructures are limited. Here, we describe a strategy for designing and fabricating nanorods using a regioselectively functionalized cellulose derivative at the air–water interface in a stepwise manner. A semisynthetic chlorophyll derivative, pyro-pheophorbide a, was partially introduced into the C-6 position of the cellulose backbone for the design of materials with specific optical properties. Remarkably, controlled formation of cellulose nanorods can be achieved, producing light-harvesting nanorods that display a larger bathochromic shift than their solution counterparts. The results presented here demonstrate that the self-assembly of functionalized polysaccharides on surfaces could lead the nanostructures mimicking the naturally occurring chloroplasts.

Nanotechnology from a bottom-up approach relies heavily on supramolecular chemistry that can potentially provide nano- and microstructures with molecular level precision of internal configurations through low-energy spontaneous processes. Moreover, supramolecular assemblies at the two-dimensional interface have great potential to be integrated into artificial devices. Studies on supramolecular chemistry at interfaces are, therefore, highly relevant for the development of nanotechnology. Another distinct aspect of supermolecules exists in their advanced dynamic properties that are anticipated to provide various stimuli-responsive systems. Here, we summarise the recent literature describing the dynamic behaviours of supermolecules at interfaces and supramolecular chemistry at dynamic interfaces categorised into three classes: (i) dynamic behaviour at solid surfaces, (ii) supermolecules at dynamic interfaces in liquid media and (iii) supermolecules at the air–water interface.

Composites of cellulose and conjugated polymers based on oligo- and polythiophene are reported, inspired by the assembly of cellulose and lignin in wood as a composite that survives harsh environmental conditions and meets most complex demands. The regioselectively oligothiophene-substituted cellulose derivatives were synthesized according to a protecting group strategy and used to prepare the polythiophene-cellulose composites through a FeCl3-initiated oxidative co-polymerization with thiophene co-monomers. The optical property of the cellulose derivatives with mono-, bi- and terthiophene moieties at the C-6 position was investigated with ultraviolet-visible (UV-Vis) and circular dichroism (CD) spectroscopy. The UV-Vis absorption spectra exhibited a broad band reflecting the intense π-π* transition within the conjugated oligothiophene side chains, which were greater than those of the corresponding reference monomers owing to their intermolecular π-electron interactions, even in solution. This was also supported by the negative CD band, indicative of cellulosic supramolecular stacking structures in solution. The soluble polythiophene-cellulose composites were prepared by the oxidative co-polymerization of the oligothiophene substituted celluloses with excess 3-hexylthiophene in the presence of FeCl3 as the oxidative initiator. The supplied amount of thiophene co-monomer was crucial for producing large π-conjugated structures and a cross-linked network structure. The soluble composites, with properties, such as electric conductivity, semiconductivity, or photoelectroactivity, were applied for the preparation of thin films which will have to be optimized for the respective application.

Halloysite is naturally available clay mineral with hollow cylindrical geometry and it is available in thousands of tons. Silver nanorods were synthesized inside the lumen of the halloysite by thermal decomposition of the silver acetate, which was loaded into halloysite from an aqueous solution by vacuum cycling. Images of individual ca. 15 nm diameter silver nanorods and nanoparticles were observed with TEM. The presence of silver inside the tubes was also verified with STEM-EDX elemental mapping. Nanorods had crystalline nature with [111] axis oriented ~68° from the halloysite tubule main axis. The composite of silver nanorods encased in clay tubes with the polymer paint was prepared, and the coating antimicrobial activity combined with tensile strength increase was demonstrated. Coating containing up 5% silver loaded halloysite did not change color after light exposure contrary to the sample prepared with loading with unshelled silver nanoparticles. Halloysite tube templates have a potential for scalable manufacturing of ceramic encapsulated metal nanorods for composite materials.

A novel cellulose derivative, 6-O-dihydrophytylcellulose (DHPC), was first synthesized via a ring-opening polymerization and allowed to self-assemble onto an air-water interface. Langmuir-Blodgett (LB) films were characterized with atomic force microscope (AFM), UV-vis spectroscopy, and Fourier transform infrared spectroscopy. The surface pressure-area (pi-A) isotherms for DHPC and beta-carotene (betaC) mixture indicated strong interaction between these compounds to pack well. Thus, DHPC has the ability to anchor betaC in the monolayer. It was proved that a betaC-DHPC monolayer was transferred successfully onto a substrate, yielding Y-type LB films by UV spectroscopic analysis. The transmission and reflection-absorption IR spectra (RAS) indicated that the dihydrophytyl chains had almost trans-zigzag conformation and were oriented nearly perpendicular to the substrate. AFM section analysis revealed the thickness per layer to be 2.32 nm. Consequently, DHPC was found to be an appropriate matrix to fabricate the mixed LB films containing betaC.