Kazuki Sugimura

Cuticular membrane of Fuyu persimmon fruit is strengthened by triterpenoid nano-fillers.

The mechanical defensive performance of fruit cuticular membranes (CMs) is largely dependent on the molecular arrangement of their constituents. Here, we elucidated nano-sized interactions between cutin and triterpenoids in the cuticular matrix of Fuyu persimmon fruits ( Diospyros kaki Thunb. cv. Fuyu), focusing on the mechanical properties using a combination of polymer analyses. The fruit CMs of Fuyu were primarily composed of wax (34.7%), which was predominantly triterpenoids followed by higher aliphatic compounds, and cutin (48.4%), primarily consisting of 9,10-epoxy-18-hydroxyoctadecanoic acid and 9,10,18-trihydroxyoctadecanoic acid. Based on the tensile tests of the CM, the removal of wax lead to a considerable decrease in the maximum stress and elastic modulus accompanied by an increase in the maximum strain, indicating that wax is of significant importance for maintaining the mechanical strength of the CM. Wide-angle X-ray diffraction and relaxation time measurements using solid-state 13C nuclear magnetic resonance indicated that the triterpenoids in the cuticular matrix construct a nanocomposite at a mixing scale below 20-24 nm; however, the higher aliphatic compounds did not exhibit clear interactions with cutin. The results indicated that the triterpenoids in the cuticular matrix endow toughness to the CM by functioning as a nanofiller.

Calcium Phosphate Mineralization in Cellulose Derivative/Poly(acrylic acid) Composites Having a Chiral Nematic Mesomorphic Structure

Calcium phosphate mineralization was conducted by using polymer composites of liquid-crystalline (ethyl)cellulose (EC) or (hydroxypropyl)cellulose (HPC) with poly(acrylic acid) (PAA) as a scaffolding medium for the inorganic deposition. The EC/PAA and HPC/PAA samples were prepared in colored film form from EC and HPC lyotropic liquid crystals of left-handed and right-handed chiral nematics, respectively, by polymerization and cross-linking of acrylic acid as the main solvent component. The mineralization was allowed to proceed in a batchwise operation by soaking the liquid-crystalline films in an aqueous salt solution containing the relevant ions, Ca(2+) and HPO4(2-). The calcium phosphate-deposited EC/PAA and HPC/PAA composites (weight gain, typically 15-25% and 6-11%, respectively) retained the chiral nematic organization of the respective original handedness but exhibited selective light-reflection of longer wavelengths relative to that of the corresponding nonmineralized samples. From X-ray diffraction and energy-dispersive X-ray spectroscopy measurements, it was deduced that the calcium and phosphorus were incorporated inside the polymer matrices in three forms: amorphous calcium phosphate, hydroxyapatite, and a certain complex of PAA-Ca(2+). Dynamic mechanical analysis and thermogravimetry revealed that the inorganic hybridization remarkably enhanced the thermal and mechanical performance of the optically functionalized cellulosic/synthetic polymer composites; however, the effect was more drastic in the EC/PAA series rather than the HPC/PAA series, reflecting the difference in the deposited mineral amount between the two.

Liquid Crystals of Cellulosics: Fascinating Ordered Structures for the Design of Functional Material Systems

This article surveys progress in both fundamental and applied research related to cellulosic liquid crystals, mainly of chiral nematic order. These liquid crystals are divided into two different classes, namely cellulosic macromolecules and cellulose nanocrystals (CNCs), depending on the mesogenic constituent. We start with a review of the fundamental and chiroptical characteristics of molecular liquid crystals of representative cellulose derivatives and then discuss recent efforts on the design and construction of functional material systems (such as stimuli-sensitive optical media and novel hybrids with minerals). These systems make use of the liquid crystalline molecular assembly of cellulosics. The survey of the other class of cellulosic liquid crystals deals with colloidal suspensions of CNCs obtained by acid hydrolysis of native cellulose fibers. Following the review of fundamental aspects related to the isotropic–anisotropic phase separation behavior of CNC suspensions, attention is directed to current applications of free-standing colored films, polymer composites reinforced with CNCs as mesofiller, and inorganic hybridizations using CNC chiral nematics as template. Some comments and the outlook for future explorations are also offered.

Cellulose propionate/poly( N -vinyl pyrrolidone- co -vinyl acetate) blends: dependence of the miscibility on propionyl DS and copolymer composition

AbstractBlend miscibility of cellulose propionate (CP) with synthetic copolymers comprising N-vinyl pyrrolidone (VP) and vinyl acetate (VAc) units was examined, and a data map was constructed as a function of the degree of substitution (DS) of CP and the VP fraction in the copolymer component. Results of differential scanning calorimetry and Fourier transform infrared measurements indicated that the pairing of CP/P(VP-co-VAc) formed a miscible or immiscible blend system according to the balance in effectiveness of the following factors: (1) hydrogen bonding between residual hydroxyls of CP and VP carbonyls of P(VP-co-VAc); (2) steric hindrance of propionyl side-groups to the interaction specified in (1); (3) intramolecular repulsion between the two units constituting the vinyl copolymer; and, additionally, (4) structural affinity between two segmental moieties involving the propionyl group and VAc unit, respectively. The factor 3 inducing intercomponent attraction is responsible for the appearance of a so-called “miscibility window” in the miscibility map, and the factor 4 substantially expands the miscible region whole, wider relative to those in the maps for the corresponding blend series based on cellulose acetate and butyrate. In further refined estimation by dynamic mechanical analysis and T1 ρH quantification in solid-state 13C NMR, it was found that the miscible blends of hydrogen-bonding type (using CPs of DS < 2.7) were completely homogeneous on a scale within a few nanometers, whereas the polymer pairs situated in the window region (using CPs of DS > 2.7) formed blends exhibiting a somewhat larger size of heterogeneity (ca. 5–20 nm).

Blends and Graft Copolymers of Cellulosics

This chapter is a general introduction to the present monograph and first describes the significance of the studies on “Blends and Graft Copolymers of Cellulosics” in the research field of compositional materials based on cellulose and related polysaccharides. Secondly, some technical key-terms and methods used for characterizing cellulosic blends and graft copolymers are explained. Finally, the outline of this book is provided by summarizing the main subjects of the constituting chapters with a perspective to tie together the subjects.

Mesomorphic glass-forming ionic complexes composed of a cholesterol phthalate and 1-C n -3-methylimidazolium: phase transition and enthalpy relaxation behavior

AbstractIonic complexes consisting of a mesogenic cholesterol derivative and 1-alkyl (Cn)-3-methylimidazolium (CnMim) (n = 6–18) were prepared from ethanol solutions containing an equimolar mixture of cholesterol hydrogen phthalate (CHP) and 1-Cn-3-methylimidazolium hydroxide; the imidazolium hydroxide was obtained by anion exchange of 1-Cn-3-methylimidazolium bromide. The complex samples, termed [CnMim][CHP], were examined to evaluate their thermal transition patterns. Excluding the two samples (n = 6, 8) that showed no definite ordered phase, the complexes with n ≥ 10 formed a cholesteric (n = 10, 12) or smectic (n = 14–18) mesophase in a considerably wide range of temperatures; this wide range reflects the additional thermotropic property of the salts of CnMim with longer alkyl chains. These fluid mesophases transformed into a mesomorphic vitreous solid without crystallization in a usual cooling process. For the glassy mesomorphic samples of selected complexes (n = 10, 18), the enthalpy relaxation behavior was followed as a function of the aging temperature and time, and the data were analyzed in terms of a Kohlrausch–Williams–Watts (KWW) type of stretched exponential equation. A very narrow distribution of relaxation times was observed for the “liquid crystalline glasses”, indicating the high uniformity of the relaxation mode.We prepared a series of ionic complexes, [CnMim][CHP] (n = 6–18), by neutralizing cholesterol hydrogen phthalate (CHP) with 1-alkyl (Cn)-3-methylimidazolium hydroxide ([CnMim][OH]) derived from [CnMim][Br]. The complexes of n ≥ 10 formed a thermotropic mesophase in each individual temperature range and solidified into a mesomorphic glass upon cooling, although two samples of n = 6 and 8 showed no ordered structure. Enthalpy relaxation behavior of the mesomorphic glasses (n = 10, 18) was also examined as a function of the aging temperature and time

Cellulosic Polymer Blends 1: With Vinyl Polymers

This chapter reviews recent studies on blends of conventional cellulose esters (CEs), such as cellulose acetate (CA), cellulose propionate (CP), and cellulose butyrate (CB), with non-crystalline vinyl (co)polymers mainly comprising the N-vinyl pyrrolidone (VP) unit. The mixing behavior of the CE/VP-containing copolymer blends is seriously affected by the chain length (i.e., carbon number) and degree of substitution (DS) as to the acyl substituent of the CE component, and by the VP fraction in the copolymer component. Relatively low-substituted CEs are commonly miscible with VP-containing copolymers by virtue of hydrogen bond formation between the CE-hydroxyls and VP-carbonyls. The blend systems using CP and CB with higher DSs impart a “miscibility window” involved in the monomer composition that constitutes the copolymer component. This observation is interpretable as a result of the indirect CE–copolymer attraction driven by intra-copolymer repulsion. A convincing argument for the miscibility behavior is provided by assessing the attractive or repulsive interactions between the blend constituents in terms of the viscometric interaction parameter. In addition to the basic characterization of the blend miscibility and intermolecular interaction, we also survey some useful applications of miscible CE blends to functional films exhibiting improved adsorption, optical, or thermomechanical properties. Particular attention is paid to the molecular orientation and optical anisotropy induced in deformed films of CA/VP-methyl methacrylate polymer blends.

Superparamagnetic IPN gels of carrageenan/PHEMA excelling in shape retention

Iron oxide nanoparticles-incorporated carrageenan (CAR)/PHEMA composites of interpenetrating network (IPN) type were successfully prepared by in situ ferrite synthesis in the polymer network. The IPN structure was constructed at CAR/PHEMA compositions of 15/85 and 40/60 (wt/wt) by polymerization and cross-linking of 2-hydroxyethylmethacrylate as an impregnating solvent of CAR gels. As a result of this IPN construction, the composites were firm and showed a good shape-retentivity in their gelatinous state. SQUID magnetometry and X-ray diffractometry were conducted for evaluation of the magnetic property of the inorganic-hybridized IPN composites. Magnetite particles with 10-30nm sizes were distributed inside the IPNs treated with the repeatable ferrite synthesis; thereby, the hybrids displayed a superparamagnetic character at ambient temperature. Specifically, the 40/60 CAR/PHEMA IPN imparted a practically passable value (10-15emu (g sample)-1) of saturation magnetization. The present IPN system offers a potential for application as a biocompatible magnetic material used in hydro-surroundings.