Phase behavior in block copolymer-surfactant complexes

초록

Block copolymer-surfactant complexes, based on the self-assembly, can generate hierarchical structures that tune the materials properties and functions. In this work, complexed systems between polystyrene-block-poly(ethylene oxide) (PS-b-PEO) diblock copolymer and dodecylbenzene sulfonic acid (DBSA) were investigated. FT-IR and DSC measurements show the shift of absorption peak due to the sulfonic acid and suppressed crystallization behavior of PEO microdomains, respectively, which indicate the strong interaction between the sulfonic group in DBSA and the lone-pair electrons of the ether linkage in PEO blocks. The cylinder-forming PS-b-PEO block copolymers exhibit the morphological change from cylindrical to lamellar structure in the thin films as well as in the bulk as the content of DBSA in complexes increases. These results are due to the increased volume fraction of PEO domains that is caused by the selective binding of DBSA with PEO blocks. Similar morphological changes were observed for PS-b-PEO block copolymers with different structure.