Synthesis and Hierarchical Self-Assembly of Rod−Rod Block Copolymers via Click Chemistry between Mesogen-Jacketed Liquid Crystalline Polymers and Helical Polypeptides

Abstract

A series of novel rod-rod diblock copolymers containing poly{2,5-bis[(4-methoxyphenyl)-oxycarbonyl]styrene} (PMPCS) and poly(γ-benzyl-L-glutamate) (PBLG) were synthesized by click chemistry from alkyne-and azide-functionalized homopolymers. The R-alkyne PMPCS homopolymers were synthesized by copper-mediated atom transfer radical polymerization with a bromine-containing R-alkyne bifunctional initiator, and R-azido PBLG homopolymers were synthesized by ring-opening polymerization of γ-benzyl-L-glutamate N-carboxyanhydride with an amino-containing R-azide initiator. The molecular structures of the rod-rod block copolymers were confirmed by 1 H NMR spectroscopy, Fourier transform infrared spectroscopy, and gel permeation chromatography analysis. The self-assembling behavior of the rod-rod block copolymers in bulk was investigated using differential scanning calorimetry, polarized light microscopy, wide-angle X-ray diffraction, and transmission electron microscopy techniques. A lamellar structure was observed with f PBLG of ∼0.50, in which PMPCS was in a columnar nematic phase and PBLG assigned to a hexagonally packed-cylinder structure (Φ H ). According to the TEM micrographs and simulated lengths of the copolymers, a stacked bilayer structure in a hexagon in lamella morphology for the selfassembly of the rod-rod block copolymers was proposed. Finally, by increasing f PBLG to ∼0.69, a microphase-separated hexagon in cylinder morphology was found, in which PMPCS formed the core of the cylinders surrounded by PBLG in Φ H phase and both rods were in an interdigitated packing.

Hybrid Block Copolymers Constituted by Peptides and Synthetic Polymers: An Overview of Synthetic Approaches, Supramolecular Behavior and Potential Applications

“…Both PMPCS and PBLG rods were packed in an interdigitated way in their own domains (Scheme X, d and e). These results obtained from TEM observation and 2D WAXD patterns [67] are significant since indicate that the development of the liquid crystal phases did not destroy the self-assembling structures from microphase separation. Thus, both mesogen-jacketed liquid crystalline polymers and polypeptides obtained from controlled polymerization methods are excellent rod-like building blocks to form rod-rod block copolymers with nanoscale hierarchical structures.…”

“…Schematic drawings of the shearing geometry with the X-axis being the shear direction are shown in (c) and (e) for lamellar and cylinder structures, respectively. Reprinted with permission from [67]. Copyright (2010) American Chemical Society.…”

Synthesis and properties of comb polymers with semirigid mesogen‐jacketed polymers as side chains

“…Therefore, MJLCP is an excellent rod‐like candidate to build block copolymers with various architectures. Researches on rod‐coil,43 rod–rod,44 triblock,45 and multiarmed46 polymers containing MJLCPs as the rod component have been investigated. However, comb polymers containing MJLCPs as rigid side chains have never been reported.…”

Synthesis, Mesomorphism and Photoluminescence of a New Class of Anthracene-based Discotic Liquid Crystals

“…The low intensity and broad shape of the reflections indicate poor molecular packing and hence reduced interaction. So, from the aforesaid data, it is confirmed that compound 4.4 shows columnar nematic phase (N Col ), which is uncommon in the family of discotics.…”