Synthesis and Structural Ordering of Gradient-Modulus Star Copolymers.
Gradient-modulus star copolymers were synthesized by crosslinking of polystyrene/isoprene tapered anions with divinylbenzene in benzene. The styrene content in the tapered arm was determined by 1H-nuclear magnetic resonance as a parameter of conversion. The composition of the arm showed the gradient structure and was in good agreement with that calculated by reactivity ratios. The solution properties of gradient-modulus star copolymers were examined by static and dynamic light scatterings. The structural ordering of gradient-modulus star copolymers were investigated by means of small-angle X-ray scattering. Gradient-modulus star copolymers formed a body-centered cubic (BCC) structure near the overlap threshold (C*). Above C*, this structure changed to the mixed lattice of BCC and face-centered cubic (FCC) structures. Copyright 1999 Academic Press.
Uchida
S
Department of Polymer Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo, 152-8552, Japan
Takeda
H
Ishizu
K