Ordering kinetics of cylindrical and spherical microdomains in an SIS block copolymer by synchrotron SAXS and rheology

Abstract

The ordering kinetics of cylindrical and spherical microdomains in a polystyrene-block-polyisoprene-block-polystyrene (SIS) copolymer were studied using synchrotron small-angle X-ray scattering (SAXS) and rheology upon quenching the sample from a disordered state to an ordered state having either spherical or cylindrical microdomains. The SIS exhibits an order to order transition at -181 "C, a lattice disordering transition at -21OOC and becomes disordered at higher temperatures. Higher order peaks in the SAXS profiles corresponding to hexagonally packed cylindrical (HEX) microdomains appeared after less than 1 h when the sample was quenched from 235°C to 170°C. When quenched from 235°C to 200°C, a broad higher order peak at -1.65 qm, corresponding to spheres with liquid-like short-range order, was persistent up to 4 h before higher order peaks corresponding to body-centered cubic (BCC) microdomains appeared. We repeated this experiment by changing temperature from one ordered state with BCC microdomains to another with HEX microdomains, and vice versa. The BCC microdomains were attained within 1 h when heating from 170 "C to 200 "C. The transition between HEX and BCC is thermoreversible. The time evolution of dynamic storage modulus G' is in good agreement with that of SAXS intensity.

Electrolytes for quasi solid-state dye-sensitized solar cells based on block copolymers

“…The SAXS signal of PS 7 ‐ b ‐PEO 136 ‐ b ‐PS 7 showed a principal reflection and smaller peaks located at relative q ‐values √2:√3:2, with respect to the main peak. This sequence can be attributed to a phase separated morphology, where spheres of PS are arranged according to a body centered cubic lattice . As the volume fraction of PEO was decreased in PS 68 ‐ b ‐PEO 136 ‐ b ‐PS 68 , the polymer presented only one reflection, indicating that PS and PEO tend to segregate in domains which, in average, are 12 nm apart.…”

Quick and Efficient Thermal Stability Enhancement of Micro‐Phase Separated Structure Formed from ABA Triblock Copolymers by Photo Cross‐Linking Approach

“…We thus found that the disordering of morphology in the neat sample was probably due to mixed effects of ODT and the thermal decomposition. Generally, it is known that the D of a micro‐phase separated structure formed by a block copolymer decreases with increasing temperatures, especially above ODT, since the segregation power between components decreases . On the other hand, it is seen in Figure b that the D of the neat sample started to increase at 170 °C and further increased with a higher slope at temperature higher than 200 °C, which is opposite to the expectation.…”

“…Since B is positive in most case, χ decreases with an increase in temperatures. When the temperature reaches certain level, order‐disorder transition (ODT) or order‐order transition (OOT) can be caused for the block copolymers with a moderate segregation power . In other cases, if the segregation power between components is specifically high, the thermal decomposition of chains occurs before ODT or OOT in the course of the temperature increase.…”

Influence of processing conditions on mechanical properties of blends of styrenic block copolymer and poly(phenylene oxide): Miscibility and microdomain size

“…Because of the incompatibility between these two blocks, with the change of chemical composition of two blocks, SBC generally forms various ordered phase morphologies, such as spherical, cylindrical, and lamellar morphologies . In addition, the phase morphology of SBC can also be obviously changed by different processing conditions and thermal history …”