Self‐Assembled Structures in Block Copolymer Blends: SAXS, SANS and TEM Study

Phenomena associated with the order‐disorder transition, microdomain morphology and phase behavior of a deuterated block copolymer (BCP) blend I / II (where I is d PS‐ block ‐ d PMMA and II is d PS‐ block ‐PI) were studied by SAXS, SANS and TEM. The studied, almost symmetric, copolymers differ essentially in microdomain morphology. One of them ( I ) is in disordered microdomain state, while the other ( II ) displays lamellar morphology at ordinary temperatures. Self‐assembled structures in blends were investigated as a function of concentration of the added microphase‐separated copolymer and temperature. The ODT positions were located in all the blends, the position of ODT depending only slightly on the concentration of the ordered copolymer. A systematic increase in long period D of the lamellar phase is observed with the growing content of the disordered copolymer. The evaluation of TEM shows the gradual diminishing of macrophase separated regions of disordered copolymer I with growing content of the lamellar copolymer II .