Structural Ordering in (AB)nStar Copolymer Solutions

Abstract

SAXS measurements that the star copolymers formed the (AB) n -type star copolymers (arm numbers n Å 14 and 16; poly-lattice with a body-centered cubic (BCC) structure near the isoprene blocks Å 23-24 mol%) were prepared by anionic copoly-overlap threshold (C*) (7). The C* is defined as a region merization of polystyrene-block-polyisoprene diblock anions with of crossover between the dilute polymer solution where the divinylbenzene. The structural ordering of such star-block copoly-coils are separate and the more concentrated solution region mers was investigated through small-angle X-ray scattering and where the coils overlap. At the C* the coils begins to be electron microscopy. (AB) n -type stars formed a body-centered cudensely packed. However, the ordering process of (AB) n bic (BCC) structure near the overlap threshold (C*). This strucstars through the C* into bulk film is not unclarified. ture changed to a mixed lattice of BCC and face-centered cubicIn this paper, we prepared the (AB) n star-block polymers (FCC) structure with increasing polymer concentration. Near the bulk, such stars formed a FCC structure. It was concluded that having many arms (n Å 14 and 16) by copolymerization of (AB) n -type stars led to hierarchical transformation of the cubic PS-block-PI diblock anions with DVB. The self-micellizalattices from the C* threshold into a continuous film. ᭧ 1998 tion behavior was investigated by dynamic light scattering. Academic PressWe also examined the process of structural ordering for star-

Lattice Formation of Peripherally Charged Star Polymers in Aqueous Solution

“…The transformation of the lattices from a C* threshold into a continuous film for (AB) n stars and polyisoprene stars with multiarm is very similar to that for the core-shell microspheres. 6,7 These results indicate that the ordering phenomena of microsphere and stars are universal self-organization for branched polymers.…”

Lyotropic Liquid Crystalline Structures Formed by Amphiphilic Heteroarm Star Copolymers

“…A number of welldefined new macromolecular architectures have been synthesized by "living" polymerization methods such as single graft, super H, star block, and heteroarm star, and their phase behaviors have been explored in the bulk. [19][20][21][22][23][24][25][26][27][28][29] Amphiphilic heteroarm star copolymers are a novel type of nonlinear block copolymers constituted of a central core bearing two kinds of pure arms of different nature (i.e., one being hydrophilic and the other hydrophobic). [30][31][32][33] Their syntheses rely on sequential "living" copolymerization techniques and comprise a three-step procedure.…”

Polydisperse star polymer solutions

“…By ultracentrifugation one can estimate the relative polydispersity in the arm number to be around 5-15 percent in carefully and slowly prepared samples. It can, however, also be much larger for fast reactions [39,40]. In a comparison between experimental data and theory, in almost all previous studies the assumptions of a monodisperse sample was implicitly made such that a natural question concerns the influence of polydispersity on the statistical properties of star polymer solutions.…”