Rod–coil block copolymers: An iterative synthetic approach via living free‐radical procedures

Abstract

A modular approach has been developed for the synthesis of rod–coil block copolymers involving the initial preparation of a macroinitiator based on the rod block followed by the growth of the coil segment with living free‐radical procedures. The key feature of this strategy is the utilization of an alkoxyamine group from the beginning of the synthesis, which serves as a solubilizing group and ensures that each rod block contains a single initiating fragment. Using this approach permits block copolymers based on insoluble biphenyl ester oligomers to be conveniently prepared with coil segments that range from styrenes to acrylates to 1,3‐dienes. The tendency of the rod segments to crystallize is strongly dependent on the weight fraction of the rod segment and the chemical nature of the coil segment. Rod–coil molecules containing at least 25–35 wt % polystyrene or poly(n‐butyl acrylate) coil segments show a two‐dimensional hexagonal arrangement of rod aggregates, as characterized by transmission electron microscopy and small‐angle X‐ray scattering. Polyisoprene block copolymers exhibit a lamellar microstructure with short rigid domains in which the rod units lie in an interdigitated smectic C arrangement. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3640–3656, 2003

Self-assembly of maltoheptaose-b-PMMA block copolymer systems: 10 nm Resolution in thin film and bulk states

“…Both the height and phase images displayed short fragmented lamellar phase which is supported by the SAXS profiles as shown in Figure 4. Such a short fragmented lamellar domains, characterized by a breaking of the rod aggregates arranged in layers parallel and perpendicular to the plane of view, were also observed in the literature for rod-coil systems with different coils lengths (Gopalan et al, 2003;Olsen & Segalman, 2005;Olsen & Segalman, 2006). The mean d value estimated from the cross-sectional profile of the phase image as show in Figure 6b was about 12 nm, which is slightly larger but consistent with the corresponding d values (d = 9.4 nm) determined by SAXS analysis.…”

Perforated Layer Structures in Liquid Crystalline Rod−Coil Block Copolymers

“…[43][44][45][46] The rigid nature enables the MJLCPs to serve as rods and form a new type of rod-coil block copolymers. Morphology and rheological behavior of rod-coil poly(styrene)-block-poly(2,5-bis-(4-butyl-benzoyl)oxystyrene) (PS-b-PBBOS) have been reported by Ober et al 47,48 Recently, a series of MJLCP based rod-coil block copolymers, poly(styrene-block-(2,5-bis[4-methoxyphenyl]oxycarbonyl)styrene) (PS-b-PMPCS), have been synthesized, and their solution self-assembly behavior has been investigated. 49 PMPCS based triblock and star block copolymers have also been synthesized.…”

Functional Liquid‐Crystalline Assemblies: Self‐Organized Soft Materials

“…[181] Liquid-crystal rod-coil molecules based on polyisoprene were prepared by living free-radical polymerization of its monomer by using a rod block molecule as a macroinitiator. [182] A new class of micro-segregated liquid crystals, the inorganic-organic hybrids, have been developed for ordering quantum dots ( Figure 17). [183] The genetically engineered M13 bacteriophage with monodisperse size and shape exhibits liquid-crystalline structures in solution states.…”