Dynamics of Composition Fluctuations in Statistical Copolymer Solutions

Abstract

Dynamic properties of styrene−methyl methacrylate (MMA) statistical copolymer solutions in benzene, a solvent isorefractive with MMA, were studied by dynamic light-scattering spectroscopy (DLS) and by pulsed-field-gradient NMR (PFG-NMR). Two separate dynamic processes were found from the DLS results in the semidilute region. The fast process was related to the cooperation diffusion mode. The slow diffusive process was attributed to the dynamics of composition fluctuations. The diffusion coefficient of the slow process has the magnitude similar to the self-diffusion coefficient determined by PFG-NMR. Dynamic property of the slow “polydispersity” mode were qualitatively interpreted in terms of the theory developed for diblock copolymers.

Heterogeneity in Semidilute Solutions of a Random Copolymer and its Relevance to Phase Fluctuation Chromatography for Separation by Chemical Composition

“…In contrast to D c , D h decreases rapidly with an increasing c. At c A 0.08 g/ml, D h decreases approximately in proportion to c -3 . A similar dependence was observed in the DLS study of random copolymer solutions [20,21] and diblock copolymer solutions. [22 -24] Also plotted is C/k 2 for the internal relaxation mode measured at h = 65 8, where C is the decay rate in g 1 (t).…”

“…The latter is considered to be an heterogeneity mode originating from the composition fluctuations in the semidilute solution, similar to the mode observed in the semidilute solutions of poly(styrene-co-methyl methacrylate). [20,21] The trend was similar in fluorotoluene. The third, weak peak in G D (D) is considered to represent an internal relaxation mode of the copolymer chain.…”

“…Recently Koňák et al studied semidilute solutions of poly(styreneco-methyl methacrylate) by DLS. [20,21] They confirmed that the slow mode was due to the heterogeneity in the composition of the solution. The two modes were also observed in semidilute solutions of a block copolymer in the disordered state.…”

Structures and dynamics of microparticles in suspension studied using ultrasound scattering techniques

“…These techniques are employed alone to investigate structures at a specific length scale or are combined to understand hierarchal structures using appropriate wavelengths . By combining static and dynamic methods, more quantitative information of polymer structures, such as the amount of aggregates, the structures of micelles, the composition fluctuations of copolymers and the mobility of polymer networks, can be obtained. We have studied the structures and properties of polymer networks, such as gels and inorganic–organic hybrids, using these techniques.…”

A Novel Structural Analysis Technique for Particle Suspensions with the Size Ranging from Nanometers to Micrometers by Ultrasound Scattering

“…More recently, microcapsules made of water/oil/water emulsion as a template were studied and the elasticity as well as shell thickness were evaluated simultaneously during their polymerization. KEY WORDS Ultrasound / Scattering / Microparticles / Dynamics / (Received March 16, 2017: Accepted May 1, 2017: Advance Publication June 8,2017) [ Kobunshi Ronbunshu, 74, 319-333 (2017)] ©2017, The Society of Polymer Science, Japan…”