Table of contents

Applications of Synchrotron Radiation and Neutron Beam to Soft Matter Science (Symposium X of IUMRS-ICA2008)

Toshiji Kanaya, Kohji Tashiro, Kazuo Sakura Keiji Tanaka, Sono Sasaki, Naoya Torikai, Moonhor Ree, Kookheon Char, Charles C Han, Atsushi Takahara

This volume contains peer-reviewed invited and contributed papers that were presented in Symposium X 'Applications of Synchrotron Radiation and Neutron Beam to Soft Matter Science' at the IUMRS International Conference in Asia 2008 (IUMRS-ICA 2008), which was held on 9–13 December 2008, at Nagoya Congress Center, Nagoya, Japan.

Structure analyses of soft materials based on synchrotron radiation (SR) and neutron beam have been developed steadily. Small-angle scattering and wide-angle diffraction techniques clarified the higher-order structure as well as time dependence of structure development such as crystallization and microphase-separation. On the other hand, reflectivity, grazing-incidence scattering and diffraction techniques revealed the surface and interface structural features of soft materials. From the viewpoint of strong interests on the development of SR and neutron beam techniques for soft materials, the objective of this symposium is to provide an interdisciplinary forum for the discussion of recent advances in research, development, and applications of SR and neutron beams to soft matter science. In this symposium, 21 oral papers containing 16 invited papers and 14 poster papers from China, India, Korea, Taiwan, and Japan were presented during the three-day symposium. As a result of the review of poster and oral presentations of young scientists by symposium chairs, Dr Kummetha Raghunatha Reddy (Toyota Technological Institute) received the IUMRS-ICA 2008 Young Researcher Award.

We are grateful to all invited speakers and many participants for valuable contributions and active discussions.

Organizing committee of Symposium (IUMRS-ICA 2008)

Professor Toshiji Kanaya (Kyoto University) Professor Kohji Tashiro (Toyota Technological Institute) Professor Kazuo Sakurai(Kitakyushu University) Professor Keiji Tanaka (Kyushu University) Dr Sono Sasaki (JASRI/Spring-8) Professor Naoya Torikai (KENS) Professor Moonhor Ree (POSTECH) Professor Kookheon Char (Seoul National University) Professor Charles C Han (CAS) Professor Atsushi Takahara(Kyushu University)

Frontier of Polymeric Nano-Soft-Materials, Precision Polymer Synthesis, Self-assembling and Their Functionalization (Symposium Y of IUMRS-ICA2008)

Seiichi Kawahara, Rong-Ming Ho, Hiroshi Jinnai, Masami Kamigaito, Takashi Miyata, Hiroshi Morita, Hideyuki Otsuka, Daewon Sohn, Keiji Tanaka

It is our great pleasure and honor to publish peer-reviewed papers, presented in Symposium Y 'Frontier of Polymeric Nano-Soft-Materials Precision Polymer Synthesis, Self-assembling and Their Functionalization' at the International Union of Materials Research Societies International Conference in Asia 2008 (IUMRS-ICA2008), which was held on 9–13 December 2008, at Nagoya Congress Center, Nagoya, Japan.

'Polymeric nano-soft-materials' are novel outcomes based on a recent innovative evolution in polymer science, i.e. precision polymer synthesis, self-assembling and functionalization of multi-component systems. The materials are expected to exhibit specific functions and unique properties due to their hierarchic morphologies brought either by naturally-generated ordering or by artificial manipulation of the systems, e.g., crystallization and phase-separation. The emerging precision synthesis has brought out new types of polymers with well-controlled primary structures. Furthermore, the surface and interface of the material are recognized to play an important role in the outstanding mechanical, electrical and optical properties, which are required for medical and engineering applications. In order to understand structure-property relationships in the nano-soft-materials, it is indispensable to develop novel characterization techniques.

Symposium Y aimed to provide recent advances in polymer synthesis, self-assembling processes and morphologies, and functionalization of nano-soft-materials in order to initiate mutual and collaborative research interest that is essential to develop revolutionarily new nano-soft-materials in the decades ahead.

Four Keynote lectures, 15 invited talks and 30 posters presented important new discoveries in polymeric nano-soft-materials, precision polymer synthesis, self-assembling and their functionalization. As for the precision polymer synthesis, the latest results were provided for studies on synthesis of polyrotaxane with movable graft chains, organic-inorganic hybridization of polymers, supra-molecular coordination assembly of conjugated polymers, precision polymerization of adamantane-containing monomers, production of high density polymer brush and synthesis of rod coil type polymer. The state-of-the-art results were introduced for the formation of nano-helical-structure of block copolymer containing asymmetric carbon atoms, self-assembling of block copolymers under the electric field, self-assembling of liquid crystalline elastomers, preparation of nano cylinder template films and mesoscopic simulation of phase transition of polymers and so forth. Moreover, recent advantages of three-dimensional electron microtomography and scanning force microscopy were proposed for analyses of nano-structures and properties of polymeric multi-component systems. Syntheses, properties and functions of slide-ring-gel, organic-inorganic hybrid hydrogels, hydrogel nano-particles, liquid-crystalline gels, the self-oscillating gels, and double network gels attracted participants' attention. Modifications of naturally occurring polymeric materials with supercritical carbon dioxide were introduced as a novel technology.

Some of the attractive topics are presented in this issue.

We are grateful to all the speakers and participants for valuable contributions and active discussions.

Organizing committee of Symposium Y (IUMRS-ICA 2008)

Chair Seiichi Kawahara (Nagaoka University of Technology, Japan)

Vice Chairs Rong-Ming Ho (National Tsing Hua University, Taiwan) Hiroshi Jinnai (Kyoto Institute of Technology, Japan) Masami Kamigaito (Nagoya University, Japan) Takashi Miyata (Kansai University, Japan) Hiroshi Morita (National Institute of Advanced Industrial Science and Technology, Japan) Hideyuki Otsuka (Kyushu University, Japan) Daewon Sohn (Hanyang University, Korea) Keiji Tanaka (Kyushu University, Japan)

All papers published in this volume of Journal of Physics: Conference Series have been peer reviewed through processes administered by the proceedings Editors. Reviews were conducted by expert referees to the professional and scientific standards expected of a proceedings journal published by IOP Publishing.

The melt-isothermal crystallization behaviour has been investigated for isotactic polypropylene (iPP) by means of time-resolved simultaneous measurements of small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD) using synchrotron radiation source in SPring-8. The time-resolved Fourier-transform infrared spectral (FTIR) measurements were also performed to clarify the formation process of helices. The SAXS data were analyzed on the basis of Guinier (isolated domains) and Debye-Bueche (correlated domains) theories and correlation function (stacked lamellae). The results were combined with the FTIR data, allowing us to draw the concrete structural evolution process including the formation of regular helices and their growth, the correlation of higher density domains consisting of these helices, and the increment of correlation between the neighbouring lamellae to build up the stacked lamellar structure of higher crystallinity.

The structural evolution in the isothermal crystallization process of nylon 10/10 from the melt has been clarified concretely on the basis of the time-resolved infrared spectral measurement as well as the synchrotron wide-angle and small-angle X-ray scattering measurements. Immediately after the temperature jump from the melt to the crystallization point, the isolated domains consisting of the hydrogen-bonded random coils were formed in the melt, as revealed by Guinier plot of SAXS data and the infrared spectral data. With the passage of time these domains approached each other with stronger correlation as analyzed by Debye-Bueche equation. These domains transformed finally to the stacked crystalline lamellae, in which the conformationally-regularized methylene segments of the CO sides were connected each other by stronger intermolecular hydrogen bonds to form the crystal lattice.

The phase transition behaviour of polyethylene-b-poly(ethylene oxide) (PE-b-PEO) diblock copolymer with relatively short chain lengths has been studied on the basis of temperature dependent infrared and Raman spectral measurements and synchrotron WAXD/SAXS simultaneous measurements, from which the concrete structural changes were deduced successfully from the various levels of molecular chain conformation, chain packing mode and higher-order structure. The higher-order structure has been found to transform between lamella, perforated lamella, gyroid, cylinder and sphere structures. The inner structural changes occurring in the polyethylene and poly(ethylene oxide) parts have been related with these morphological changes. The morphological transition from lamella to gyroid occurs with keeping the crystalline state of polyethylene parts. This apparently curious transition can be interpreted reasonably by assuming the thermally-activated chain motion in the crystal lattice, which may play an important role as a trigger to induce the morphological change from lamella to gyroid. This idea was supported by the measurement of half-width of Raman anti-symmetric CH₂ stretching band sensitive to the thermal mobility of alkyl chains.

We report neutron reflectivity results on a three-layer polystyrene thin film on Si wafer, consisting of alternative stacking of deuterated layer ~20 nm thick and hydrogenated layer ~30 nm thick. In the experiments we have evaluated the film thickness of each layer and the surface roughness and interfacial widths as a function of temperature below and above the glass transition temperature T_g. It was found that the top layer has T_g lower than the bulk T_g by ~18 K, and the middle layer has almost the same T_g as the bulk. On the other hand, the bottom layer did show very high T_g above 130 °C. The results show the distribution of T_g in the thin film. It was also found that the interfacial width between the top and middle layers increased more rapidly than that between the middle and bottom layers above ~110 °C, showing higher mobility of polystyrene in the top layer because of the lower T_g.

Effect of layer structures on the GISAXS intensity analysis of Ge nanodots capped with Si layer has been examined by Born Approximation and Distorted Wave Born Approximation simulations. It is concluded that when the dots are small enough in the out-of-plane directions, most of the structural information are deduced by simple BA. The effect of refracted wave became important when the area of interest is close to the Yoneda line or the analysis deals with small difference in the intermediate q range.

Analyzes were made of the particle scattering function P(k), z-average radii of gyration and intrinsic viscosities for amylose tris phenylcarbamate samples having different weight-average molecular weight M_w in 1,4-dioxane (DIOX), 2-ethoxyethanol (2EE), methyl acetate and 4-methyl-2-pentanone at 25 °C and in ethyl acetate at 33°C, on the basis of the wormlike cylinder model with or without excluded volume to determine the contour length per residue h and the Kuhn segment length. The h values in a ketone and esters were found to be significantly larger than those in DIOX and 2EE. Furthermore, the discrepancy between the experimental P(k) for an ATPC sample (M_w = 18700) and the theoretical values at high k (absolute value of the scattering vector) region (k > 3 nm^-1) became more significant with decreasing h, suggesting that the P(k) data at the k region reflect the helical structure of the polymer.

Influence of α-methyl group on molecular aggregation states and surface physicochemical properties of poly(fluoroalkyl acrylate)s [PFA-C_y, where y is fluoromethylene number in R_f group] and poly(fluoroalkykl methacrylate)s [PFMA-C_y] thin films were systematically investigated. Spin-coated PFA-C_y and PFMA-C_y thin films were characterized by dynamic contact angle measurements and grazing-incidence wide-angle X-ray diffraction (GIWAXD) measurements. GIWAXD data revealed that fluoroalkyl side chains of PFA-C_y and PFMA-C_y with y≥8 formed regular structures in the surface region as well as bulk one. However, the degree of orientation and ordering of the R_f groups of PFMA-C₈ thin films was low. Also, the receding contact angle (θ_r) of PFMA-C₈ thin films was lower than that of PFA-C₈ ones. By annealing treatment, the θ_r of PFMA-C₈ was increased. These results suggest that the R_f groups of PFMA-C₈ were disordered due to presence of the α-methyl group. The R_f groups became ordered to pack closely each other by annealing treatment, so that the water repellency was increased.

Relationship between the transfection efficiency and the supramolecular structure of the lipoplexes consisting of DNA, a benzyl amine derivative (BA), and two neutral co-lipids (DOPE and DLPC) were examined. At a composition of BA:DOPE:DLPC = 1:2:1; where the highest efficiency was attained, SAXS showed that the micelles before adding DNA formed a hexagonally-packed cylinder and addition of DNA improved the packing order. This phenomenon may be interpreted by intercalation of DNA between the preformed micellar cylinders. At a composition of BA: DLPC=1:1, where the lowest efficiency was observed, the micelle adopted a spherical form and addition of DNA induce a structural transition from the sphere to a hexagonally packed cylinder, and then a lamellar form. Fitting with a multilayer model suggested that DNA was included into the hydrophobic layer of the complex. Comparison of these two compositions suggests that difference in the DNA location in the lipoplex is related to the transfection efficiency.

Fluoropolymer brush with crystalline side chains was prepared by surface-initiated atom transfer radical polymerization of 2-(perfluorooctyl)ethyl acrylate (FA-C₈) from a flat silicon substrate. The crystallization and the molecular aggregation structures of polymer side chain at the outermost surface and internal region in the brush film were characterized by grazing incidence X-ray diffraction (GIXD) measurement using two different incident angles of X-ray. At the air interface of PFA-C₈ brush film, the rod-like R_f group was oriented perpendicular to the surface forming a hexagonal packing structure to reduce surface energy. In contrast, the oriented R_f groups parallel to the substrate coexisted at the internal region in the brush. This unique depth dependence of crystalline state of the fluoropolymer brush was observed by surface-sensitive GIXD measurement.

Zwitterionic and cationic polyelectrolyte brushes on quartz substrate were prepared by surface-initiated atom transfer radical polymerization of 2-(methacryloyloxy)ethyl phosphorylcholine (MPC) and 2-(methacryloyloxy)ethyltrimethylammonium chloride (METAC), respectively. The effects of ionic strength on brush structure and surface properties of densely grafted polyelectrolyte brushes were analysed by neutron reflectivity (NR) measurements. NR at poly(METAC)/D₂O and poly(MPC)/D₂O interface revealed that the grafted polymer chains were fairly extended from the substrate surface, while the thickness reduction of poly(METAC) brush was observed in 5.6 M NaCl/D₂O solution due to the screening of the repulsive interaction between polycations by hydrated salt ions. Interestingly, no structural change was observed in poly(MPC) brush even in a salt solution probably due to the unique interaction properties of phosphorylcholine units.

Swelling states of poly(3-dimethyl(methacryloyloxyethyl)ammonium propane sulfonate) (DMAPS) brush in aqueous solutions with different salt concentrations were investigated by atomic force microscopy (AFM) and neutron reflectivity measurement. The thickness of swollen poly(DMAPS) brush evaluated by AFM was increased from 212 nm up to 352 nm with an increase in salt concentration from 0 to 0.5 M. Poly(DMAPS) brush chains formed shrunk structure in a pure water due to the attractive electrostatic inter- and intra-chain interaction of sulfobetaine groups, while the brush chains in NaCl aqueous solution were stretched up because the hydrated salt ions screened the attractive interaction.

In order to predict the physical property of polymers, we need to know the atomic coordinates including hydrogen atoms as accurately as possible. However, polymer samples give us limited number of broad X-ray reflections in general. In order to improve this problem, we have made many efforts to collect the X-ray diffraction data as accurate as possible. In this paper, we report the structure analysis including the extraction of hydrogen/deuterium atomic positions for the oriented polyoxymethylene by the combination of X-ray diffraction method with neutron diffraction method. In such a cases of polydiacetylene giant single crystal the bonded electron density distribution was evaluated along the skeletal chain by the so-called X-N method based on the wide-angle X-ray diffraction data and the wide-angle neutron diffraction data.

We studied nanoporous structures templated from block copolymer morphologies using carbon dioxide swelling and de-swelling. The volume where carbon dioxide occupied turns into empty space after de-swelling. As a pressure of carbon dioxide increases, the effective volume fraction of block copolymer changes due to the selectivity of carbon dioxide. The swollen morphology of block copolymer changes from its original neat morphology and a variety of nanoporous structures appear after de-swelling. Consequently, unique nanoporous stuructures depending on the process pressure were obtained.

Hierarchical structural features of Vinylidene fluoride-trifluoroethylene (VDF-TrFE) copolymers during the phase transition have been successfully investigated in detail by in-situ simultaneous measurements of DSC and SAXS/WAXD utilizing synchrotron radiation. In a heating process at a constant rate of 1 °C/min, a broad endothermic peak was measured for a VDF-TrFE copolymer from ca. 75°C to ca. 135°C. On the other hand, WAXD data indicated that the phase transition from the crystal form II to the high-temperature (HT) phase began to occur at ca. 105°C. With an increase in temperature from ca. 75° C to ca. 105° C (temperature region A), lamellar staking distance (long period) and lamellar thickness evaluated in SAXS data analyses slightly increased though the crystallite size (the lateral dimension of the lamellae) was almost constant. The (110) reflections of the crystal form II gradually decreased in integrated intensity and scattering from the amorphous region increased instead, which implied that lamellae in crystal form II became partially disordered before the phase transition.

Crystallization behavior of polyethylene (PE) on silicon wafers in solution casting processes has been successfully traced by time-resolved grazing-incidence small-angle and wide-angle X-ray scattering (GISWAXS) measurements utilizing synchrotron radiation. A p-xylene solution of PE kept at ca. 343 K was dropped on a silicon wafer at ca. 298 K. While the p-xylene evaporated naturally from the dropped solution sample, PE chains crystallized to be a thin film. Raman spectral measurements were performed simultaneously with the GISWAXS measurements to evaluate quantitatively the p-xylene the dropped solution contained. Grazing-incidence wide-angle X-ray scattering (GIWAXS) patterns indicated nucleation and crystal growth in the dropped solution and the following as-cast film. GIWAXS and Raman spectral data revealed that crystallization of PE was enhanced after complete evaporation of the p-xylene from the dropped solution. The [110] and [200] directions of the orthorhombic PE crystal became relatively parallel to the wafer surface with time, which implied that the flat-on lamellae with respect to the wafer surface were mainly formed in the as-cast film. On the other hand, grazing-incidence small-angle X-ray scattering (GISAXS) patterns implied formation of isolated lamellae in the dropped solution. The lamellae and amorphous might alternatively be stacked in the preferred direction perpendicular to the wafer surface. The synchrotron GISWAXS experimental method could be applied for kinetic study on hierarchical structure of polymer thin films.

We propose a simple method to obtain double network (DN) hydrogels containing 85–90wt% water with various kinds of mechanical performance by taking advantage of the heterogeneity of the first network: By synthesizing the first network in a poor solvent that enhancing the heterogeneity of the network, the DN gel exhibits rich mechanical behavior: from brittle, ductile (necking), to paste-like. For a proper heterogeneity, a distinct necking deformation with extensibility of about 20 times is observed for post-necking gels. The necking gels have a high initial modulus (0.1–0.5 MPa) and high mechanical toughness (nominal fracture stress: 1 MPa), both values are similar to that of living tissues.

Anionic polymerizations of a series of para-substituted styrene derivatives containing adamantyl groups, 4-(1-adamantyl)styrene (1), 3-(4-vinylphenyl)-1,1'-biadamantane (2), 4-(1-adamantyl)-α-methylstyrene (3), 4-(1-adamantyloxy)styrene (4), 1-adamantyl 4-vinylbenzoate (5), and N-(1-adamantyl)-N-(4-vinylbenzylidene)amine (6), were carried out in THF at -78 °C. The polymerizations of 1–6 quantitatively proceeded to afford the well-defined polymers possessing the predicted molecular weights and the narrow molecular weight distributions (M_w/M_n = 1.03–1.10). The stability of the propagating chain ends was confirmed by the sequential copolymerizations of 1–6 with various monomers. The resulting poly(1), poly(2), poly(3), poly(4), poly(5), and poly(6) showed remarkably high glass transition temperatures at 234, 232, 273, 184, 227, and 254 °C, respectively, indicating the drastic substituent effect of adamantyl groups.

Static and dynamic light scattering measurements were performed for dilute polyrotaxane solutions in different types of solvent systems, i.e. dimethylacetamide (DMAc) or dimethylformamide (DMF) containing 1-6 wt% lithium chloride (LiCl), 1 M aqueous sodium hydroxide (NaOH) and dimethylsulfoxide (DMSO). No aggregation of the polyrotaxane in DMF/LiCl was confirmed in the present study. Radius of gyration of the dissolved polyrotaxane was largest in NaOHaq., followed by values in amide solvents/LiCl and that in DMSO, and was probably dominated not by Coulombic repulsion but by the mutual affinity between solvent and polyrotaxane. Ratio of radius of gyration to hydrodynamic radius suggested the flexible random-coiled conformation in DMSO and relatively more extended, semi-flexible ones in amide solvents/LiCl and NaOHaq. The obtained values of second virial coefficient and weight average molecular weight seemed to be affected by a potential change in differential refractive index increments, caused by selective macrocationization or ionization.

Formation of star-like nanogels with two different arms via cross-linking reaction of complementarily reactive diblock copolymers was successfully accomplished. The two types of diblock copolymers, consisting of poly(methyl methacrylate) (PMMA) or polystyrene (PSt) block and alkoxyamine-based cross-linkable block, were prepared by atom transfer radical polymerization (ATRP) methods. The cross-linking reactions were carried out by merely heating their mixture, and traced by gel permeation chromatography (GPC) and multi-angle light scattering (MALS) measurements. The diblock copolymers were reacted in complementarily reactive systems, showing that all star-like nanogels have necessarily two types of arms as PMMA and PSt chains.

Strain-induced crystallization of natural rubber (NR), dispersed in styrene-butadiene rubber (SBR), was investigated in relation to dimensional feature of a dispersoid and crosslink density of NR by measuring tear energy (G) of crosslinked NR/SBR blends. The crosslinked NR/SBR blends in ratios of 1/9 and 3/7 by weight were prepared by mixing masticated NR and SBR with an internal mixer at a rotor speed of 30 rpm, followed by crosslinking with dicumyl peroxide on a hot press at 444 K for 60 min. The G, measured in wide-ranges of temperature and tear rate, was superposed into a master curve with a Williams-Landel-Ferry shift factor. The G of the NR/SBR(3/7) blend abruptly decreased to a level comparable to that of SBR at about melting temperature of NR crystals formed on straining. The temperature, at which the dramatic decrease in the G occurred, was associated with the dimensional feature of the NR dispersoid and the crosslink density.

Coordinations of poly(vinylene-arsine)s (1) towards transition metal ions were carried out to estimate the coordination ability of phenyl-substituted poly(vinylene-arsine) (1a) and methyl-substituted poly(vinylene-arsine) (1b). No 1a-Co complex was obtained upon addition of an acetone solution of 1a to an acetone solution of cobalt (II) chloride hexahydrate. On the other hand, 1b-Co complexes were obtained in the reactions at different cobalt salt-1b feed ratios. As in the usual case, the bivalent complexes of the reaction run corresponding to the feed ratio of 1:1 [CoCl₂]/[repeating unit of 1b] oxidized readily in air to give very stable complexes of trivalent cobalt. On the other hand, the bivalent complexes of the reaction runs corresponding to the feed ratios of 1:4 and 1:10 both exhibited unusual stability against air oxidation owing to the higher concentration of 1b in the reaction mixture. Reactions of 1 and bis(2,2'-bipyridyl)ruthenium(II) dichloride also provided polymer complexes. In all the cases, 1b had higher coordination property than 1a due to its lower steric hindrance.

A nematic elastomer film with a 90° twist orientation between the top and bottom surfaces is prepared by chiral imprinting methods. The reactive achiral nematic monomers and crosslinkers are photopolymerized in the presence of a controlled amount of unreactive chiral dopant. The elastomer films possess a 90° twist orientation even after the removal of the chiral dopant. The films exhibit an elongation and contraction in the direction at an angle of 45° relative to the mesogen orientations at the top and bottom surfaces in response to cooling and heating across the nematic-isotropic transition temperature, respectively.

Density functional simulations are performed to study various self-assembling micellar structures in amphiphilic block copolymer solutions. It was shown that onion structures (stacked multilayer structures) are formed when the hydrophilic interaction is weak. Simulation results imply that the onion structures are different from monolayer vesicle structures which is formed when the hydrophilic interaction is rather strong. The difference and similarity between the vesicle structures and onion structures, or between their kinetic formation pathways are discussed.

Graftpolyrotaxanes having graft chains on the wheel components were prepared from main chain-type polyrotaxane having monofunctional cyclodextrin wheels and terminal end-reactive poly(ethylene glycol) (PEG). The well-defined polyrotaxane having mono(6-hydroxyl) permethyl-α-CD (monoOH-α-CD) as the wheel components and a polytetrahydrofuran (PTHF) axle with bulky end-capping groups was synthesized by the two pathways; (i) synthesis by solid-state end-capping of pseudopolyrotaxane consisting of monoOAc-α-CD and hydroxy-terminated PTHF and (ii) one-pot synthesis using monoOH-α-CD and amine-terminated PTHF in water. The grafting reaction on the wheel moieties of the resulting polyrotaxane was carried out by acylation reaction with PEG-mono-carboxylic acid derivatives in high conversion yields. To estimate the relative rotary movement of CDs and the axle polymer in the polyrotaxane and graftpolyrotaxane, the rotational correlation time (τ_c) of polyrotaxanes was estimated from the longitudinal relaxation time (T₁) of ¹³C NMR. The results clearly indicate that the graftpolyrotaxane described here is a new type of graft polymer in terms of the special circumrotation behavior such as the independent rotary movement of CDs with the graft chain and the axle polymer.

The metal-catalyzed radical addition reaction can be evolved into two different polymerization mechanisms, i.e.; chain- and step-growth polymerizations, while both the polymerizations are based on the same metal-catalyzed radical formation reaction. The former is a widely employed metal-catalyzed living radical polymerization or atom transfer radical polymerization of common vinyl monomers, and the latter is a novel metal-catalyzed radical polyaddition of designed monomer with an unconjugated C=C double bond and a reactive C-Cl bond in one molecule. The simultaneous ruthenium-catalyzed living radical polymerization of methyl acrylate and radical polyaddition of 3-butenyl 2-chloropropionate was achieved with Ru(Cp*)Cl(PPh₃)₂ to afford the controlled polymers, in which the homopolymer segments with the controlled chain length were connected by the ester linkage.

Thermal expansion behavior was investigated for tangusten zirconium phosphate (Zr₂(WO₄)(PO₄)₂ (ZWP)) particulate filled poly(ether ether ketone) (PEEK) composite. ZWP is known as ceramic filler with a negative thermal expansion. By incorporating ZWP with 40 volume %, the linear thermal expansion coefficient of the PEEK composite was reduced to almost same value (2.53 X 10^-5 K^-1) with that of aluminum. This decrease was found to be quite effective for the decrease of the residual stress at the interface between aluminum plate and the composite.

Nano-matrix structure of a graft-copolymer consisting of deproteinized natural rubber (DPNR) and polystyrene (PS) was observed through field-emission scanning microscopy combined with a focused gallium (Ga) ion beam (FIB-SEM). The graft-copolymer was carefully stained with osmium tetraoxide for more than a week to avoid a charge-up through FIB-SEM. Field emission SEM images of the graft-copolymer were taken after etching its surface with the Ga ion at each interval and they were reconstructed to obtain the three-dimensional image of the nano-matrix structure. The NR particles of about 0.5 μm in diameter were found to be dispersed into the nano-matrix of PS, which connected to each other on all directions. The dimensional feature of the NR particles was dependent upon an expression of orthogonal views of the 3D image.

Measurements are presented how chain and microphase-separated structures of ultrathin polyurethane (PU) films are controlled by the thickness. The film thickness is varied by a solution concentration for spin coating. The systems are PUs prepared from commercial raw materials. Fourier-transform infrared spectroscopic measurement revealed that the degree of hydrogen bonding among hard segment chains decreased and increased with decreasing film thickness for strong and weak microphase separation systems, respectively. The microphase-separated structure, which is formed from hard segment domains and a surrounding soft segment matrix, were observed by atomic force microscopy. The size of hard segment domains decreased with decreasing film thickness, and possibility of specific orientation of the hard segment chains was exhibited for both systems. These results are due to decreasing space for the formation of the microphase-separated structure.

The time evolution of the phase separating pattern during the spinodal decomposition (SD) of a specimen was observed at the same volume of the specimen using X-ray computerized microtomography (X-ray CT). A careful examination of time-dependent three-dimensional (3D) images revealed that bridge-like domains played an important role in the phase separation dynamics. In the course of the SD, some bridge-like domains became thicker, while the others became thinner. It was found that the pressure difference across the interface, which is quantified through the mean curvature of the interface, influences such interface dynamics.

We have been developing new techniques to evaluate polymer nano-alloys and nano-composites. This "nanotechnology" can be classified into nano-three dimensional (3D) measurement, nano-physical properties evaluation systems, and nano-spectroscopy. As for the nano-3D measurement, we developed polymer oriented energy-filtered 3D transmission electron microscopy. With this method, we can access important 3D structural and elemental information that cannot be obtainable from ordinary TEM. Nano-physical properties evaluation systems were also established by developing atomic force microscopy force-distance curve measurement. The distribution of mechanical properties such as Young's modulus and adhesive energy was quantitatively obtained on high lateral resolution. These methods give new pieces of information unobtainable by the conventional techniques on polymer nanotechnology. Several results are shown here.

In concentrated polymer brushes (CPBs) prepared by surface-initiated living radical polymerization, graft chains in a good solvent are highly stretched, nearly to their full length, giving properties quite different and unpredictable from those of semi-dilute polymer brushes (SDPBs) previously studied. This paper reviews our recent studies on the microtribology of confronted CPBs in solvents. Atomic force microscopy revealed that the CPBs of poly(methyl methacrylate) and poly(styrene) showed dramatically low frictional coefficients in good solvents compared with those of the corresponding SDPBs. This was reasonably ascribed to confronted CPBs hardly mixing with each other due to their huge osmotic and elastic interactions. The lubrication mechanism of CPBs was discussed according to the sliding-speed dependency of frictional coefficient, and two different mechanisms, boundary and hydrodynamic lubrications, were suggested. Thermo-responsive lubrication was also demonstrated for the CPB of poly(N-isopropyl acrylamide). We believe that these studies will open up a new route to precision surface modification for "super" lubrication.

Polymer nano-adhesion between a cantilever tip coated with polymer and a flat polymer film was studied by a light-lever system using an atomic force microscope. The polymer interface was adhered at a temperature above the surface glass transition temperature for a given time. Nano-adhesion force (F_nano), at which the tip was detached from the surface, was estimated from the deflection of the lever with a known spring constant. Nano-adhesion strength (G_N) was simply obtained dividing F_nano by the contact area, which was estimated on the basis of Johnson-Kendall-Roberts theory. The time evolution of the interfacial thickness was independently examined by dynamic secondary ion mass spectrometry. Interestingly, G_N increased with increasing interfacial thickness. However, it can be hardly judged whether G_N is proportional to the interfacial thickness with the exponent of 1 or 2. Then, temperature dependence of G_N was examined. Above the bulk glass transition temperature, the relation between temperature and G_N was well expressed by a Williams-Landel-Ferry type equation. This means that the nano-adhesion strength is governed by friction between segments. Once this is accepted, G_N should be proportional to the interfacial thickness with the exponent of 2.

A hyperbranched polymer (HPS-DC) synthesized using N,N-diethylamino -dithiocarbamoylstyrene as an inimer and a hyperbranched poly(4-methylstyrene) (HPS-H) prepared by hydrogenation of the HPS-DC are characterized in tetrahydrofuran (THF) solutions by static and dynamic light scattering measurements. The experimental values of z-averaged mean-square radius of gyration (<S²>_z^1/2) and hydrodynamic radius (R_H) of the HPS-H have smaller dimensions than those of the linear polystyrene (PS) at the same degree of polymerization (N_w), whereas the R_H of the HPS-DC in the region of N_w < 700 is larger than that of the linear PS at the same N_w. The N_w-dependence of <S²>_z^1/2 and R_H for the HPS-H are described by a randomly trifunctional branched polymer model with the molecular weight per a branch point (4.55 × 10³ g/mol) and the chain dimensions of the linear PS in THF at 25 °C.