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Two types of lamellar stacking model were proposed for the inner structure of the melt-grown spherulites of isotacticpolypropylene (iPP): the edge-on structure (flat lamellar planes stand on the spherulite plane, and a*-axis // growth direction of spherulite, b-axis ┴ spherulite plane, and c-axis // spherulite plane) and the flat-on structure (flat lamellar planes lay on the spherulite plane, a*-axis // growth direction, b-axis // spherulite plane, and c-axis ┴ spherulite plane). After a literature review was performed, the observed X-ray scattering data were not high quality and could not be used to establish these bimodal structures; moreover, the X-ray data analyses were not performed satisfactorily. As a result, the derivations of actual structures were still debatable. We performed simultaneous time-resolved WAXD/SAXS measurements using a synchrotron X-ray microbeam technique. The collected data were classified into three sets of completely different WAXD/SAXS patterns. Detailed quantitative analysis enabled the determination of the spatial orientations of the stacked lamellae and related crystallographic axes. Although the bimodal structure of iPP spherulites was considered to be a well-known and already-established concept for long years, the bimodal structure was successfully confirmed for the first time in the present study, making the concrete discussions on the growth mechanism of the iPP spherulites possible.

Nanoimprint lithography (NIL) is a simple and high-resolution patterning method. Nanoimprinted structures can be fabricated not only as surface structures but also as ‘buried’ structures for applications such as electro-optical devices. However, a precise and nondestructive evaluation method for nanoimprinted structures has not yet been established. Synchrotron radiation ultra-small angle X-ray scattering (SR-USAXS) is a nondestructive and high-resolution characterization method. In this study, we fabricated nanostructures on a poly(lactic acid) (PLA) film using NIL. In addition, the nanoimprinted PLA film was covered with a polystyrene thin film to fabricate a ‘buried’ structure. The fabricated surface and the ‘buried’ structure were evaluated using SR-USAXS. The scattering pattern was clearly obtained from the surface and the ‘buried’ structure. The size of the ‘buried’ structure, which was estimated from the diffraction pattern, was in good agreement with that of the surface structure. These results indicate that SR-USAXS is powerful tool for the nondestructive and precise characterization of surface and ‘buried’ structures.

To gain a better understanding of the function of soft-material thin films, one should investigate the multiscale structural information from the surface roughness down to the atomically truncated structures at microarea. To achieve such an integrated investigation, a new experimental system has been launched by coupling with the measurement techniques, which include 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 beamline of SPring-8. The high brilliance and low divergence beam allows the surface and interface structure measurements from the angstrom to the micrometer scale using a soller-slit system for proper optimization of measurement precision. A typical structural analysis of the soft-material film was performed to evaluate the practical performance and specifications of the experimental system.

We present a mechanistic study of the curing process of liquid–crystalline epoxy resins by the simultaneous measurement of small-angle X-ray scattering/wide-angle X-ray scattering using synchrotron radiation. The systems studied consist of a diglycidyl ether of terephthalydene-bis(4-amino-3-methylphenol) epoxy component and three types of aromatic amine-type curing agents 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylethane and m-phenylenediamine. The systems studied all exhibit similar thermosetting behaviors; first, the epoxide group reacts with an amine moiety of the curing agent, followed by the formation of the nematic domains in the early stage of the process. The nematic-to-smectic conversion proceeds after an incubation period, implying that a critical amount of nematic volume is necessary for phase transition. We found that the transformation continues beyond the conversion of 80% of the epoxide-amine bond formation and the corresponding entire polymer network formation. The volume fraction of smectic phases after completion of the reaction differs according to the structure of the curing agents. The study clarifies the mechanistic sequence and the preference for smectic phase formation both in terms of time sequence and the dependence of the structure on the curing agents.

We have studied the melt-elongational crystallization of isotactic polypropylene. In 2010, we observed that ‘nano-oriented crystals (NOCs)’ were formed when the elongational strain rate () exceeded a critical value (). In this study, we have clarified the formation mechanism of NOCs using the crystallization temperature (Tc) dependence of the formation of NOCs and structural studies using small angle X-ray scattering, SAXS, wide angle X-ray scattering, WAXS, and optical microscopy. We propose a ‘chain reaction model’ for the formation of NOCs; the locally oriented melt is formed by the melt elongation, which significantly accelerates nucleation. The generated nuclei accelerate the formation of the locally oriented melt, which further accelerates the nucleation. We formulate a relationship between and the nucleation rate (I) based on the above model. We have confirmed that NOCs are formed in the range of Tc=150–167?°C. We have obtained the degree of supercooling (?T) dependence of I from the Tcdependence of . Here, we estimated an equilibrium melting temperature in the oriented melt Tm0=220?°C from the observation of NOC formation, where the error in Tm0was a few tens of K. The observed I was well-fitted with the well-known equation of for homogeneous nucleation from classical nucleation theory (CNT), where C is a constant. Therefore, we conclude that the formation of NOCs is primarily controlled by a homogeneous nucleation process, which confirms the chain reaction model.

We carried out an isothermal crystallization experiment on isotactic polypropylene (iPP) containing 0.2 and 3.0% of 1,3:2,4-bis(p-methylbenzylidene)sorbitol (PDTS) as a nucleation additive. Compared with neat iPP, the induction period before crystallization was markedly shortened, and thus the quench depth became shallower by ~15?°C. Avrami analysis showed that the Avrami exponent was very sensitive to temperature; it decreased from 3.5–4 to 2 with a decrease in the crystallization temperature Tc(that is, an increase in the cooling depth) of only 4?°C, in contrast with iPP, where the exponent was 4 for all Tc. Small-angle X-ray scattering showed an upturn at low q only for iPP/PDTS, suggesting that the gel network made from PDTS was formed before iPP crystallization. This study shows that the iPP/PDTS crystallization kinetics and its temperature sensitivity were determined by the competition between two events: PDTS network growth and iPP crystallization.

The dimensions and intermolecular interactions of surface-grafted and unbound, free polyampholytes, poly[3-(N-2-methacryloyloxyethyl-N,N-dimethyl) ammonatopropanesulfonate] (PMAPS) and poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC), were estimated in an aqueous NaCl solution over a wide range of salt concentrations (Cs). The free PMAPS and PMPC fractionated by a recycling preparative size-exclusion chromatography system were characterized in aqueous NaCl solutions for Csover a range from 0 to 5.0?M by static light scattering and dynamic light scattering (DLS) measurements. The hydrodynamic radius (RH) and the concentration coefficient of the diffusion coefficient (kD) for PMPC were independent of Cs, whereas those for PMAPS were strongly dependent on Cs. Monodisperse silica nanoparticles immobilized with PMAPS (SiNP-PMAPS) and PMPC (SiNP-PMPC) by surface-initiated atom transfer radical polymerization were characterized in aqueous NaCl solutions for Csover a range from 0 to 5.0?M by DLS and synchrotron radiation small-angle X-ray scattering (SAXS) measurements. The SAXS profiles from SiNP-PMAPS and SiNP-PMPC solutions were well described by the core-shell model, taking into account interacting self-avoiding chains and assuming a Schulz-distributed core with two fitting parameters.