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Abstract Our earlier studies on block copolymers polystyrene‐poly(ethylene oxide) has allowed to state the influence of the molecular weight of the copolymer and of its composition on the refolding of the crystallized poly(ethylene oxide) chains. To precise the effect of the nature of the amorphous block, we have studied by X‐ray diffraction and differential scanning calorimetry, the lamellar crystalline structures exhibited by block copolymers polybutadiene‐poly(ethylene oxide) (BEO) in the presence of a preferential solvent of one block: xylene for polybutadiene (PB), acetic acid or acrylic acid for poly(ethylene oxide) (PEO). In systems BEO copolymer/preferential solvent of PEO, the lamellar structure with crystallized PEO chains (LCC) exists at temperatures below about 45°C and for solvent concentrations ranging from 0 to a value characteristic of the copolymer. In the LCC structure, the chains of PEO crystallize in two layers; the solvent forms a third layer located between the PEO layers. We have studied the influence of the nature of the amorphous block on the variation of the structural parameters with the solvent concentration. In systems BEO copolymer/preferential solvent of PB, the lamellar structure with crystallized PEO chains (LC) appears at temperatures below about 50°C and for all solvent concentrations where the mesophase exists. In the LC structure, the chains of PEO crystallize folding in two superposed layers. We have established the influence of the solvent concentration and the nature of the amorphous block on the number of folds and the crystallinity of the PEO chains.
Gervais et al. (Sun,) studied this question.