Structure and rheology of blends of SB star block copolymer and homo polystyrene

It is known that many kinds of phase separated structures appear when A homopolymer is added to AB diblock copolymer, depending on the molecular weight ratio of A to A-block and the volume fraction of A homopolymer. In the present study, phase separated structures of blends of 4-arm SB star block copolymer and homo polystyrene (PS) are observed by TEM and dynamic viscoelastic behaviors of the blends are investigated. The molecular weights of PS and S-block are 5.97K and 9.51K. The blend ratios of the copolymer/PS are 75/25, 70/30, 67/33 and 60/40 (wt/wt). With the addition of PS, lamellar structure of the copolymer changes into perforated lamellar (PL), gyroid (G), cylinder with disordered gyroid, and hexagonal cylinder (H). The storage modulus G' of PL and H shows the power law behavior, while G' of G is somewhat higher than others.