Transformation of cubic symmetry for spherical microdomains from face-centred to body-centred cubic upon uniaxial elongation in an elastomeric triblock copolymer

Experimental observation of the transformation of cubic symmetry from face-centred cubic (f.c.c.) to body-centred cubic (b.c.c.) for spherical microdomains upon uniaxial stretching of poly(1,3-cyclohexadiene)-block-poly(ethylene-co-but-1-ene)-block-poly(1,3-cyclohexadiene) triblock copolymer, having φ_PCHD = 0.293, M_n = 5.73 × 10⁴, M_w/M_n = 1.09, is reported. First, the sample was subjected to flow treatment at 493 K for 2 h; then it was annealed at 473 K for 2 h to prepare the f.c.c. structure. The sample was subsequently subjected to uniaxial stretching. After the load was completely removed, small-angle X-ray scattering measurements were conducted. It was found that the f.c.c. packing was transformed to the well ordered b.c.c. packing upon uniaxial stretching.