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Self‐assembled structures in polystyrene‐ block ‐polyisoprene‐ blend ‐polystyrene and polystyrene‐ block ‐poly(methyl methacrylate)‐ blend ‐polystyrene or ‐ blend ‐poly(methyl methacrylate) in the strong segregation regime
Author(s) -
Holoubek Jaroslav,
Baldrian Josef,
Hromádková Jiřina,
Steinhart Miloš
Publication year - 2011
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/pi.2994
Subject(s) - polystyrene , copolymer , methyl methacrylate , materials science , polymer chemistry , methacrylate , morphology (biology) , poly(methyl methacrylate) , flory–huggins solution theory , polymer , composite material , biology , genetics
This study deals with the investigation of microphase‐separated morphology and phase behaviour in blends of polystyrene‐ block ‐polyisoprene with homopolystyrene and blends of polystyrene‐ block ‐poly(methyl methacrylate) with homopoly(methyl methacrylate) or homopolystyrene in the strong segregation regime using small‐angle X‐ray scattering and transmission electron microscopy as a function of composition, molecular weight of homopolymers, r M and temperature. Parameter r M = M H / M C (where M H is the molecular weight of homopolymer and M C that of the corresponding block copolymer) was selected to encompass behaviour of the chains denoted as a ‘wet brush’ (i.e. r M < 1). The relative domain spacing D / D o increases in the regime 0 < r M ⩽1 with increasing concentration of homopolymer w P and increasing r M but depends on the specific implemented morphology. We tested a new approximate D / D o versus w P relation in the strong segregation regime using block copolymers of high molecular weights. It is shown that the parameters r M and χ 3/2 N determine the slope of the D / D o versus w P relation in the strong segregation regime and the new approximation generally matches the experimental data better than the approximations used so far. Copyright © 2010 Society of Chemical Industry