A zone heating method, which imposes the moving temperature-gradient (▿T) field on ordering process of various melts in general, enabled to control a macroscopic orientation of microdomain structures in block copolymer bulk. We applied the method to a polystyrene-block-polyisoprene diblock copolymer forming hexagonally packed cylindrical domains (hex−cyl) in the absence of external fields. We discovered that the method creates the following special texture of hex−cyl:  (1) The texture seemingly consists of volume-filled columnar grains with the grain axis parallel to the ▿T axis (defined as the Oz axis). (2) The cylinder axis always orients perpendicular to the Oz axis with a rotational angle φ of the cylinder axis around the Oz axis being fixed within a grain but statistically varying randomly among different grains. (3) One set of the (100) plane of hex−cyl preferentially oriented perpendicular to Oz axis with a small rotational degree of freedom around the cylinder axis. We interpret that the special texture is a consequence of the surface-induced order−disorder transition of the block copolymer under the moving ▿T field.

Polyurethane elastomers (PUEs) containing trans-1,4-bis­(isocyanato­methyl)­cyclohexane (1,4-H6XDI) have been synthesized by polymerizing 1,4-H6XDI with poly­(oxytetra­methylene) glycol and 1,4-butanediol. The molecular aggregation state and mechanical properties of these PUEs have been compared with those exhibited by PUE analogues made of MDI and diols. The hard segment chains in the 1,4-H6XDI-based PUEs are found to readily crystallize and form strong hydrogen bonds due to a high symmetry of 1,4-H6XDI molecule. Consequently, the 1,4-H6XDI-based PUEs exhibit well-organized hard segment domains. This leads to their generally superior mechanical properties as compared to those of the well-known MDI-based PUEs. 1,4-H6XDI’s lack of aromatic moieties is expected to greatly enhance color stability of resulting PUEs. All the above features suggest 1,4-H6XDI could replace MDI in a range of applications.

In a previous paper (Macromolecules 2007, 40, 5923), we reported that a zone heating method, which imposes the moving temperature-gradient (∇T) field on ordering process of various melts in general, enabled to control a macroscopic orientation of hexagonally packed cylindrical microdomain structures (hex-cyl) of block copolymer (bcp) bulk. In this report, we have investigated how the variation of the moving rate of ∇T affects the macroscopic orientation by using two kinds of polystyrene-block-polyisoprene bcps having different mobility. We found that the upper limit of the moving rate required to induce the unique texture and orientation of hex-cyl became large with increasing the mobility of the bcps. These results indicate that the moving rate should be smaller than the intrinsic growth rate of the hex-cyl grains in the undercooled disordered melt.

We applied the zone heating method to cylinder-forming diblock copolymers (bcp) for controlling the orientation of the hexagonally packed cylindrical microdomain structures (hex-cyl) and reported the results of the structure analysis by small-angle X-ray scattering (SAXS) in our previous paper [Mita et al. Macromolecules 2007, 40, 5923]. In this report, we present the results of the real-space analysis of the zone-heated bcp by using polarized optical microscopy and transmission electron microscopy. The real-space analysis elucidated that the zone heating creates the columnar-shaped grains extending along the temperature gradient (∇T) direction: within a given grain the cylinder axes are aligned perpendicular to ∇T axis with a fixed rotational angle φ around ∇T axis: the angle φ varies statistically randomly over many grains. These results firmly verified the columnar grain model proposed by the previous Fourier-space analysis. Furthermore, the real-space analysis elucidated the average lateral size and shapes of the grains, the commensuration of the hex-cyl at the grain boundaries, and the fact that this commensuration was achieved by the distortion of the domain spacing of the hex-cyl near the grain boundaries from its equilibrium value.