Order–disorder transition and ordering kinetics in binary diblock copolymer mixtures of styrene and isoprene

Abstract

Monte Carlo simulation of the order-disorder transition of a symmetric cyclic diblock copolymer systemThe order-disorder transition ͑ODT͒ and the ordering kinetics have been studied in two symmetric diblock copolymers of styrene and isoprene and their binary mixtures with rheology. The binary mixtures formed a single microdomain ͑with lamellar morphology͒ composed of short and long chains as confirmed by small angle x-ray scattering ͑SAXS͒. The order-disorder transition temperature ͑T ODT ͒, obtained from the discontinuity in the storage modulus GЈ, varies linearly with the number average degree of polymerization. For shallow quenches, the ordering kinetics proceed via nucleation and growth. The characteristic time of this process scales with N Ϫ1/3 , where N is the Ginzburg parameter, in agreement with the theoretical predictions ͓G. H. Fredrickson and K. Binder, J. Chem. Phys. 91, 7265 ͑1989͔͒. Our results indicate that the ordering kinetics of symmetric diblock copolymers near the ODT are fluctuation controlled.

Maximizing the grain growth rate during the disorder‐to‐order transition in block copolymer melts

“…Rosedale and Bates 9 followed the kinetics of the disorder-to-order transition in a poly(methylbutylene)-block-poly(ethylethylene) copolymer melt with time-resolved rheology and found that the kinetics slowed down monotonically with increasing temperature. Floudas et al 10 estimated the time required to complete the disorderto-order transition in a polystyrene-block-polyisoprene copolymer melt by the same method and found the same result: slower kinetics at higher temperatures. This suggests that in both cases, 9,10 the experiments were conducted at T Ͼ T max ; that is, order formation was controlled by thermodynamic factors.…”

“…Floudas et al 10 estimated the time required to complete the disorderto-order transition in a polystyrene-block-polyisoprene copolymer melt by the same method and found the same result: slower kinetics at higher temperatures. This suggests that in both cases, 9,10 the experiments were conducted at T Ͼ T max ; that is, order formation was controlled by thermodynamic factors. This is surprising when one considers the fact that the experiments on the polystyrene-block-polyisoprene copolymer 10 were conducted at temperatures between 74 and 86°C.…”

“…This suggests that in both cases, 9,10 the experiments were conducted at T Ͼ T max ; that is, order formation was controlled by thermodynamic factors. This is surprising when one considers the fact that the experiments on the polystyrene-block-polyisoprene copolymer 10 were conducted at temperatures between 74 and 86°C. Under these conditions, frictional forces are expected to increase rapidly with decreasing temperature because of the proximity to the glass-transition temperature of the polystyrene chains.…”

“…Ordering kinetics inferred from rheology are usually obtained from the time dependence of the in-phase shear modulus (GЈ). 9,10 Simple models suggest that GЈ is mainly a function of . Thus, the kinetic measurements based on rheology reflect the time dependence of .…”

Block Copolymers in External Fields: Rheology, Flow‐Induced Phenomena, and Applications

“…In this respect, the true ODT is the so-called equilibrium ODT [67]. The kinetics of ordering of block copolymers has been studied in great detail using combination of shear rheology and time-resolved small-angle X-ray scattering (SAXS) experiments [66,[68][69][70][71]. In general, the results are well described by the Avrami equation that also applies to the kinetics of crystallization.…”