Thermoreversible Order—Order Transition between Spherical and Cylindrical Microdomain Structures of Block Copolymer

Directed Self-Assembly of Block Copolymers into Twin BCC-Sphere: Phase Transition Process from Aligned Hex-Cylinder to BCC-Sphere Induced by a Temperature Jump between the Two Equilibrium Phases

“…Phase transition processes and mechanisms in block copolymers (bcps) have been extensively and intensively investigated from practical view points to control their patterns with nanoperiodicity at will and from scientific view points that bcps are considered to be one of the best model systems to investigate precisely and deeply phase-transition mechanisms and processes of soft matters because of their slow dynamics. − It is well-known that bcps exhibit the phase transitions called order–order transition (OOT) in the weak segregation regime by changing temperature. , Among various OOT’s, the OOT between cylindrical microdomains in hexagonal symmetry (hex-cylinder) and spherical microdomains in body-centered cubic symmetry (bcc-sphere) also has been investigated theoretically ,− and experimentally. − …”

Time-Resolved High-Resolution SAXS Studies of OOT Process and Mechanism from Hex-Cylinder to BCC-Sphere in a Polystyrene-block-polyisoprene Diblock Copolymer

“…In previous papers, , we reported the mechanism of the thermoreversible order–order transition (OOT) between spherical microdomains on a body-centered cubic lattice (hereafter denoted as bcc-sphere) and cylindrical microdomains on a hexagonal lattice (hereafter denoted as hex-cyl) of a polystyrene (PS)- block -polyisoprene (PI) diblock copolymer (bcp). Many studies dealing with the same kind of OOT have been reported for various bcps, and the mechanism of the transition process is found to have the universality of the so-called epitaxial transformation in which the cylinder axis is transformed to the ⟨111⟩ axis of the bcc-sphere, and {10} and {11} lattice planes of hex-cyl are transformed to {110} and {112} lattice planes of bcc-sphere, respectively. − However, the details of the epitaxial process have not yet been well investigated experimentally.…”

“…In previous papers, , we reported the mechanism of the thermoreversible order–order transition (OOT) between spherical microdomains on a body-centered cubic lattice (hereafter denoted as bcc-sphere) and cylindrical microdomains on a hexagonal lattice (hereafter denoted as hex-cyl) of a polystyrene (PS)- block -polyisoprene (PI) diblock copolymer (bcp). Many studies dealing with the same kind of OOT have been reported for various bcps, and the mechanism of the transition process is found to have the universality of the so-called epitaxial transformation in which the cylinder axis is transformed to the ⟨111⟩ axis of the bcc-sphere, and {10} and {11} lattice planes of hex-cyl are transformed to {110} and {112} lattice planes of bcc-sphere, respectively. − However, the details of the epitaxial process have not yet been well investigated experimentally. This is mainly due to the following two experimental difficulties in exploring in situ and real-time structural evolution of the intermediate structures during the OOT process: (1) Such intermediate structures would be very unstable and have a little retention time.…”

Thermal Study on Phase Transitions of Block Copolymers by Mesoscopic Simulation

“…Experimental and theoretical studies have confirmed that HPC phase develops transient metastable phases during thermal heating process (Kimishima et al, 2000;Krishnamoorti et al, 2000;Rodríguez-Hidalgo et al, 2009). The order-order transition pathway from HPC to spherical phase is sketched schematically in Fig.…”

“…During the past two decades have been reported theoretical and experimental studies of diblock copolymers, where the ODT and OOT transitions play a main role in the structure control and consequently in the physical properties control of these polymeric materials (Kimishima et al, 2000;Kim et al, 2006;Bodycomb et al, 2000;Court et al, 2006;. It is well-known that the poly(styrene)-poly(isoprene) diblock copolymer exhibits a wide variety of classical phases with specific morphologies such as: BCC, HPC, OBDD, LAM and HPL.…”