Ordering on multiple lengthscales in a series of side group liquid crystal block copolymers containing a cholesteryl-based mesogen

Abstract

Hierarchical ordering in a side group liquid crystal block copolymer is investigated by differential scanning calorimetry, polarized optical microscopy, small-angle X-ray and neutron scattering (SAXS and SANS) and transmission electron microscopy (TEM). A series of block copolymers with a range of compositions was prepared by atom transfer radical polymerization, comprising a polystyrene block and a poly(methyl methacrylate) block bearing chiral cholesteryl mesogens. Smectic ordering is observed as well as microphase separation of the block copolymer. Lamellar structures were observed for far larger volume fractions than for coil-coil copolymers (up to a volume fraction of liquid crystal block, f LC 5 0.8). A sample with f LC 5 0.86 exhibited a hexagonal-packed cylinder morphology, as confirmed by SAXS and TEM. The matrix comprised the liquid crystal block, with the mesogens forming smectic layers. For the liquid crystal homopolymer and samples with high f LC , a smectic-smectic phase transition was observed below the clearing point. At low temperature, the smectic phase comprises coexisting domains with monolayer S A,1 coexisting with interdigitated S A,d domains. At high temperature a S A,1 phase is observed. This is the only structure observed for samples with lower f LC . These unprecedented results point to the influence of block copolymer microphase separation on the smectic ordering.

Recent Progress in Sustainable Polymers Obtained from Cyclic Terpenes: Synthesis, Properties, and Application Potential

“…[3b, 117] Many similar 17-containing monomers have been polymerized through different radical polymerization methods. [118,119] Furthermore, fibrilso fp olymers derived from a( terpenebased) bile acid were capable of inducing biomimetic mineralization. [120] Pyrroled erivatives containing such bile acid moieties have also been synthesized and polymerized.…”

Directing the Smectic Layer Orientation by Shear Flow in Hierarchical Lamellar‐within‐lamellar Liquid Crystalline Diblock Copolymers

“…[16,22,23] The BCP is shown to self-assemble into a lamellar-within-lamellar morphology where the mesogens form smectic A layers within the lamellar microphase separated BCP phase. On the basis of previous reports [20][21][22][23][24][25] and the length of the spacer unit, the smectic layers are expected to orient perpendicular to the BCP lamellae in bulk. To study the problem, the local isotropic structures are extended over macroscopic length scale using large amplitude oscillatory shear flow and the aligned samples are thereafter characterized using small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM).…”

Lamellar-in-lamellar structure of binary linear multiblock copolymers

“…They became an attractive subject for experimental [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] and theoretical [16][17][18][19][20] investigations due to the possibilities to form structures combining different periodicities. One of the first observations of a doubleperiodic self-assembled structure involved the self-assembly in polystyrene-block-poly͑4-vinylpyridine͒ ͑PS-b-P4VP͒ diblock copolymers with hydrogen-bonded pentadecylphenol ͑PDP͒ side chains to the P4VP block.…”