SAXS Studies on Structure Formation in Microemulsion‐Triblock Copolymer Systems

Small angle X‐ray scattering (SAXS) measurements were performed on water/AOT (sodium di‐2‐ethyl‐hexylsulfosuccinate)/i‐octane(2,2,4‐trimethylpentane) w/o‐microemulsions with various amounts of block‐copoly(oxyethylene/isoprene/oxyethylene). Addition of copolymer causes an aggregation of the microemulsion droplets. The first aggregation step is the formation of dimers (two droplets connected by a copolymer molecule). From the experimental form factors, structure and size of the dimers could be calculated. In particular, we could show that the radius of the droplets increases by about 10% after absorbing a copolymer block. The distance between two droplets and the width of the distance distribution were determined as well. From the decrease of the number of free nanodroplets as a function of the amount of copolymer it could be concluded that roughly one in four copolymer molecules acts as a bridge between two droplets.