Lamellar Nanoconfinements Effects in Discotic Liquid Crystalline Block Copolymers

Abstract

We have evaluated the effect of slit‐like nanoconfinements imposed on columnar discotic phases within a discotic block copolymer displaying a lamellar microphase. Findings are that the columns are oriented uniformly along the lamellar normal within the plane of thin films, that a rectangular rather than a hexagonal columnar phase is formed within the discotic regions, that the thermodynamic stability of the columnar phase is strongly reduced relative to the low molar mass model compounds and finally, that the isotropic phase can be unusually strongly supercooled with respect to the columnar phase formation. Slit‐like nanoconfinements allow thus to induce novel types of the intrinsic order and columnar orientations.magnified image

Triphenylene-Based Side Chain Liquid Crystalline Block Copolymers Containing a PEG block: Controlled Synthesis, Microphase Structures Evolution and Their Interplay with Discotic Mesogenic Orders

“…A 2.5 equiv. molar excess (relative to hydroxyl group) of TPmC 10 COOH ( 4 ) and one week of reaction time were applied to ensure high transformation efficiency of side hydroxyl groups, the mesogen attachment through polymer analogous reaction can be almost quantitative under well-chosen reaction conditions . Moderate overall yields of 44–58% have been achieved for the DLC polymers synthesis as listed in Table .…”

“…Researches for preparing TP-based discotic liquid crystalline polymers were pioneered by Ringsdorf and co-workers. , Since then, some TP-based side chain − and main chain discotic LC polymers − have been synthesized. A few TP-based discotic LCBCPs have also been reported so far. − A coil–coil–disk triblock oligomer polyethylene- block -poly(ethylene oxide)- block -pentakis(pentyloxy) triphenylene (PE- b -PEO- b -P5T) was synthesized by Zhu and co-workers, the discotic TP mesogens sandwiched between amorphous PEO layers exhibited a nematic columnar (N col ) to nematic discotic phase (N D ) transition at ca. 23 °C .…”

“…23 °C . Recently, a TP side chain discotic block copolymer with amorphous polystyrene (PS) coil block was prepared by Wendorff and co-workers showing uniform columnar orientation perpendicular to the lamellar direction confined by the slit-like nanoconfinement . A triblock LCBCP with a TP-based main chain polymeric liquid crystal capped at both ends with PEG blocks exhibited hexagonal packed PEG rods in a matrix of columnar LC and the photocurrent generation of such copolymers was reported. − TP-based side-chain copolymers of 2,6,7,10,11-pentapentyloxy-3-(3-acryloylpropyloxy) triphenylene (PPAT) and tert- butyl acrylate ( t -BA) were synthesized through atom transfer radical polymerization (ATRP) method with a limited degree of polymerization (DP) around eight of the discotic segment, and hexagonal columnar discotic mesophases were observed for the block copolymers. , …”

Hierarchical Self-Organization and Uniaxial Alignment of Well Synthesized Side-Chain Discotic Liquid Crystalline Polymers

“…In contrast with intensively studied calamitic mesogens based LCPs with extensive applications such as in high modulus fibers, optoelectronic devices, and sensors, thus far surprisingly limited progress has been made on discotic LCPs since first reported in 1983 by Ringsdorf . Although some examples of side-chain discotic LCPs have been explored adopting various discotic mesogens such as derivatives of triphenylene (TP), − hexabenzocoronene (HBC), , multialkynylbenzene, perylene, porphyrin, and phthalocyanine (Pc), whereas there is almost no systematic work pertinent to some fundamental questions of discotic LCPs such as molecular weight effect and the spacer length influence, despite such issues are closely correlated to their self-organized supramolecular structures thus crucial for organic electronic and optoelectronic applications …”

Controlled synthesis and microstructure tuning of PEG-containing side-chain discotic liquid crystalline block copolymers via RAFT polymerization

“…Calamitic mesogens based LCBCPs have been extensively explored as synthesized through various “living” or controlled polymerization techniques such as anionic polymerization, atomic transfer radical polymerization (ATRP), and reversible addition‐fragmentation chain‐transfer (RAFT) polymerization . However, so far there appeared very few reports on LCBCPs bearing discotic mesogens, including a few examples of side‐chain discotic LCBCPs through polymer analogous reaction, or via ATRP with some limitations, and several main‐chain type discotic LCBCPs . Such underdeveloped situation may largely result from the synthesis difficulties of discotic LCBCPs as compared to their calamitic counterparts in a controlled preparation approach, since it is a significant challenge even for the controlled synthesis of discotic liquid crystalline homopolymers .…”