Cholesterol mesogen containing monomer, cholesteryl acrylamido butyrate (CAB) with the novel spacer group drawn from 4-amino butyric acid has been demonstrated to exhibit good reactivity with 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS) to yield copolymers with CAB content as high as 15 mol % hitherto not achieved. The spacer group is shown to provide the twin benefits of enhanced reactivity and solubility in water. The high pK(a) at > or =9.90 of these copolymers estimated from potentiometric studies demonstrates packing of AMPS segments as ionic clusters. The higher CAB in copolymer C provides the most densely packed nonpolar microdomains. From fluorescence quenching studies, the cross-linking provided by the cholesterol chains favoring intra- or intermolecular aggregated structures has been established. At the air/solution interface, copolymer C exhibits the most close-packed structures exhibiting "a" of 41.2 A(2)/molecule. The effect of neutralization on the adsorption characteristics is investigated.
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http://dx.doi.org/10.1021/bm061235r | DOI Listing |
Soft Matter
September 2024
Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, Knowledge City, Manauli 140306, India.
Non-symmetrical cholesterol-based dimers have emerged as crucial materials in the field of liquid crystal research, owing to their remarkable ability to stabilize various exotic mesophases, including the blue phases (BPIII, BPII, BPI), cholesteric nematic (N*) phase, smectic blue phase (SmBP), twist grain boundary (TGB) phase, smectic A/smectic A* (SmA/SmA*) phase, and smectic C/smectic C* (SmC/SmC*) phase. These mesophases have garnered considerable attention due to their diverse applications in spatial light modulation, chiro-optical devices, optical switching, thermochromic materials, and more. In this study, we present the synthesis and comprehensive characterization of a series of non-symmetrical cholesterol-based bent-shaped dimers (1/12, 1/14, 1/16) in which the cholesterol unit is intricately linked to an aromatic mesogenic core through a flexible spacer.
View Article and Find Full Text PDFSoft Matter
May 2024
Centre for Nano and Soft Matter Sciences Arkavathi, Survey No. 7, Shivanapura, Dasanapura Hobli, Bengaluru-562162, India.
Introducing restricted rotation in a molecule, often achieved through the incorporation of double or triple bonds, constitutes a crucial approach to induce a frustrated mesophase. Furthermore, the inclusion of a chiral moiety, such as cholesterol, serves to enhance the stabilization of chiral frustrated mesophases. This study presents the synthesis and characterization of novel optically active dimers incorporating cholesterol and phenyl 3-phenylpropiolate segments interconnected by an ω-oxyalkanoyloxy spacer with varying lengths and parity.
View Article and Find Full Text PDFChemistry
February 2023
Shaanxi International Research Center for Soft Matter, State Key Laboratory for Mechanical Behaviour of Materials, Xi'an Jiaotong University, Xi An Shi, Xi'an, 710049, P. R. China.
The correlation between the size of nanoparticles, the structure and shape of mesogenic ligands and the ensuing assembly behaviour is not really understood. Closer inspection shows very surprising features. Here, 2- and 4-nm gold nanoparticles (NPs) were synthesized, and grafted with a forked ligand containing two rod-like mesogens in its branches: one cholesterol, the other with azobenzene.
View Article and Find Full Text PDFACS Macro Lett
April 2021
Department of Chemistry, The Catholic University of Korea, Bucheon, Gyeonggi-do 14662, Korea.
Metal-mediated self-assembly of chelating double-hydrophilic block copolymer has become a facile preparation strategy of great importance for the metal-chelated hybrid nanostructures. Herein, we present a delicate control over the morphology regulation of metal-chelated nanostructures by a terminal modification of polymer building blocks with mesogenic cholesterol. Such a molecular design motif at an end of chelating linear/brush-type block copolymer imparts not only additional hydrophobicity for enhanced cohesive force to facilitate the metal-mediated self-assembly, but also significant morphological alteration of a metal-chelated core that otherwise generally forms a spherical interior with cholesterol-free block copolymers.
View Article and Find Full Text PDFChem Asian J
April 2022
State Key Laboratory for Mechanical Behaviour of Materials, Shaanxi International Research Center for Soft Matter, Xi'an Jiaotong University, Xi'an, 710049, P. R. China.
We report the formation of a 3D body-centred self-assembled superlattice of gold nanoparticles whose interparticle gap, and hence its plasmonic properties, are adjustable exclusively in the xy-plane. Thus, even though the particles are spherical, their anisotropic packing generates tailorable plasmonic dichroism. The gold nanoparticles are coated with forked ligands containing two mesogens: either two cholesterols ("twin"), one cholesterol and one azobenzene ("Janus"), or a mixture of the two.
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