Volume 45 Issue 1, January 2013

Our group has developed a novel method to produce nanocellular and nanoporous structures using block copolymer as template and supercritical carbon dioxide. To characterize nanocells and nanopores, small angle X-ray scattering (SAXS) has an important role. In particular, grazing incident SAXS reveals embedded nanocellular and nanoporous structures in thin films. Additionally, SAXS can be used for in situ measurement to follow the process of nanocellular and nanoporous formation in supercritical carbon dioxide. Our recent progresses of fabrication and SAXS characterization of nanocellular and nanoporous structures will be reviewed.

Rubber-filler systems have been widely used in industry. Fillers are not dispersed homogeneously and often form hierarchical structures in rubber matrices over a wide range of length scale from nanometer to micron meters, such as primary particles, aggregates and agglomerates. The combined scattering methods are powerful tools to characterize the structures quantitatively.

A method is described that can predict the miscibility of the great majority of polyolefins based just on their chemical architecture. The miscibility of polyolefins is shown to be essentially controlled by their solubility parameters, d, which in turn depend on the chain dimensions of the chains through the packing length l_p. A method to estimate l_p from chain architecture is also shown, giving a very powerful mechanism to predict the mixing thermodynamics from chemical structure.

Various properties of ultrathin polymer films differ substantially from their bulk values. However, the critical question is whether the unusual properties are uniform throughout the films. To explore the presence of heterogeneous viscosity distributions, we have established grazing-incidence X-ray photon correlation spectroscopy for single polymer films with embedded metal nanoparticles that act as markers. In addition, the combined use of resonance enhanced X-ray scattering enables us to intensify the probing electrical field in the regions of interest within a single polymer film.

Grazing incidence small-angle neutron scattering (GISANS) allows for the investigation of nanostructures in thin films and at surfaces due to the use of a reflection geometry. Possibilities and challenges of GISANS are reviewed with several different examples of thin nanostructured polymer films. With GISANS buried lateral structures can be probed destruction free using the variable-probed depth as function of the incidence angle. By this, averaged statistical information is detected over the large illuminated sample surface.

We present a mechanistic study of the structural formation on the curing process of the liquid–crystalline epoxy with the simultaneous measurement of SAXS/WAXS using synchrotron radiation. The following behaviors were revealed: after the temperature-jump to the curing temperature, first the system forms the nematic domains; the nematic-to-smectic conversion proceeds after an incubation period; the transformation continues beyond the conversion of 80% of epoxide-amine bond formation and corresponding entire polymer network formation.

We performed small-angle and wide-angle X-ray scattering (SAXS/WAXS) measurements on poly(ethylene terephthalate) (PET) uniaxially drawn from amorphous state above the glass transition temperature. The measurements were done at a new beamline (BL) BL03XU (Frontier Softmaterial Bamline) in the synchrotron radiation X-ray facility, SPring-8, which is dedicated to development of advanced soft materials and belongs to the Advanced Softmaterial BL Consortium. We performed a calculation to reproduce the observed 2D SAXS patterns. Based on the results of the calculation we discussed the distribution of lamellar stacking direction and the relation between the lamellar length and the stacking direction.

We studied the structure of polybutadiene rubber (BR) crosslinked with zinc diacrylate (ZDA) by complementary use of small-angle X-ray scattering (SAXS) and small-angle neutron scattering (SANS) to confirm the high crosslink density region in the matrix rubber. This is the first finding of the high crosslink density segments in BR (HC-BR) crosslinked by ZDA. Tensile measurements revealed that the size and the number density of the HC-BR and ZDA aggregates are related to the mechanical property of the rubber materials.

We visualized strain field of polymer matrix using an FEM simulation based on the knowledge of 3D structural configuration of silica particles in rubber. The configuration was obtained by using the Zernike-type phase contrast x-ray imaging method.

We studied the formation mechanism of ‘nano-oriented crystals (NOCs)’ of isotactic polypropylene in elongational crystallization through crystallization temperature dependence of NOCs formation. We proposed a ‘chain reaction model’ of NOCs formation: The local oriented melt is formed by the melt elongation, which significantly accelerates nucleation; and, generated nuclei accelerate formation of local oriented melt that accelerates nucleation again. We obtained the nucleation rate (I_obs) of NOCs against the degree of supercooling (ΔT). Here, an equilibrium melting temperature in the oriented melt T_m⁰=220 ^°C is estimated from observation of NOCs formation. I_obs was well fitted by well-known equation of for homogeneous nucleation in classical nucleation theory, where C is a constant. Therefore, we concluded that NOCs formation is mainly controlled by the homogeneous nucleation process.

Simultaneous small- and wide-angle X-ray scattering studies on crystallization dynamics of poly(4-methylpentene-1) (P4MP1) from melt by Kazuki Mita, Hiroshi Okumura, Kazuki Kimura, Takeharu Isaki, Mikihito Takenaka and Toshiji Kanaya. Crystallization process of P4MP1 under an isothermal condition was investigated by means of simultaneous small- and wide-angle synchrotron radiation X-ray scattering. The changes in lamella structure and crystal lattice during the crystallization were elucidated for the first time: the lamellae thickness is kept constant, whereas the lattice constant a changes toward the most stable value. We also found that there is some inhomogeneous structure even in the melt and in the induction period and the subsequent crystallization consists of the first and the second processes.

We carried out isothermal crystallization experiment for isotactic polypropylene (iPP) containing 1,3:2,4-bis(p-methylbenzylidene)sorbitol (PDTS) as a nucleation additive. Avrami analysis for iPP/PDTS systems showed that the Avrami exponent decreased from 3.5–4 to 2 with decrease of the crystallization temperature T_c only by 4 °C, being contrasted with iPP, where the exponent was 4 for all T_c. This study shows that the iPP/PDTS crystallization kinetics and its temperature sensitiveness were determined by the competition between two events: PDTS network growth and iPP crystallization.

The effects of thermal gradient on dynamical behavior of nanoparticles dispersed in polymer matrix were studied by X-ray photon correlation spectroscopy. Anisotropic motions of nanoparticles were observed when the sample was kept in a cell using a capillary tube covered with copper block. As the same experiment using another cell without such thermal gradient clearly demonstrated that even the small thermal gradient around the probe windows caused the anisotropic dynamical behavior.

Novel horizontal-type time-of-flight neutron reflectometer SOFIA (SOFt Interface Analyzer) was installed in BL 16 of Materials and Life Science Experimental Facility at the Japan Proton Accelerator Research Complex (J-PARC). The design and performance of SOFIA reflectometer was described based on the preliminary results of the neutron reflectivity (NR) measurements of deuterated polystyrene (d-PS) thin films, Langmuir–Blodgett film and at deuterium oxide/ polymer brush interfaces. Time-resolved in-situ NR measurement at 1-min intervals was also demonstrated to observe interfacial mixing of d-PS on the PS brush surface during annealing.

The new experimental system has been launched by coupling with the measurement techniques, which are grazing incidence small/wide-angle X-ray Scattering (GISWAXS) and grazing incidence X-ray diffraction (GIXD), as well as X-ray reflectivity (XR), at the BL03XU of SPring-8. Using this integrated system, we can achieve to measure the hierarchical structure of the same sample.

The effect of the Molecular weight dispersity (MWD) on the interfacial width between a hPS brush and unbound dPS matrix has been investigated by NR measurement. The intermixing between hPS brush with narrow MWD and dPS matrix hardly occurred even after thermal annealing at 398 K because of dry-brush regime. In contrast, the intermixing of hPS brush with broad MWD and free dPS proceeded to increase the interfacial width like a wet-brush condition, in spite of high grafting density.

Polymer Journalis proud to present a special issue on theApplication of Quantum Beams to Polymer Science and Engineering, which brings together a series of articles with specially solicited topical reviews. The accompanying web focus provides additional links to related articles in this subject area from across Nature Publishing Group.