Self-Assembled Superhelical Structure of Poly(N-vinylcarbazole)-Based Donor–Acceptor Polymer at the Air–Water Interface

Abstract

Preparation of helical polymers designed for mimicking biological helices and developing supramolecular helical assemblies with a controlled helix sense still remains a major challenge. A previously unknown superhelical structure constructed by achiral random copolymer poly(N-vinylcarbazole) (PVK) with pendant azobenzene chromophores and terminal nitro moieties (PVK−AZO−NO 2 ) at the air/ water interface was systematically investigated by CD spectroscopy, AFM, and TEM. The compression of the interfacial films may induce the helices to coil up and form large superhelices with the opposite handedness in a manner analogous to forming the supercoiled tertiary structure of DNA. The structure model for the self-assembly of PVK−AZO−NO 2 into suprahelical structures at the air/water interface was also proposed.

Unraveling the forming mechanism of hierarchical helices via self-assembly of an achiral supramolecular polymer brush

“…However, it is noteworthy that the total amount of bright spots as well as fibrils almost remains unchanged on the basis of an evaluation of more than 20 independent AFM images with a scanning size of 30 × 30 μm 2 at each surface pressure (0, 2, 5, and 15 mN m −1 ), even if taking into account the decreasing surface area resulting from the compression of the monolayer film. Although we found a surface pressureinduced helical architecture of a PVK derivative in our previous work, 27 the unchanging amount of spots and fibrils during compression of monolayers suggests that the formation of the helical structures in the present work could not be attributed to such an induced effect of the surface pressure. In other words, this fact implies that such spots together with the fibrils had been fabricated in CHCl 3 .…”

“…S1A †); and (ii) interfacial assembly through a Langmuir monolayer, which can provide an ideal two-dimensional plane with a confined environment at the air-water interface, as well as the LB technique, affords excellent opportunities to construct the supramolecular structure and dynamic self-assembly of polymers, and to exert molecular-level control over the structure of organic thin films. 27 The surface pressure versus molecular area (π-A) isotherm of PVP-PDP over ultrapure water is apparently different from that of pure PVP or PDP, as shown in Fig. S2.…”

“…In our previous work, we disclosed that an N-vinylcarbazole-based copolymer can generate a superhelical structure at an air-water interface as the surface pressures increase, attributed to weak interactions between pendant groups. 27 However, it is still a significant issue in the hierarchical self-assembly of synthesized helical polymers to understand how primary and/or secondary structures of helices evolve into a stably advanced structure, e.g., tertiary and/or quaternary structures. Moreover, there is little experimental evidence to directly unravel in detail the assembly process of the hierarchical helices.…”

Covalent Modification of MoS2 with Poly(N‐vinylcarbazole) for Solid‐State Broadband Optical Limiters

“…As expected, the NLO response of the MoS 2 –PVK film changed from a prominent SA response before annealing to a strong RSA signal after annealing. This is because enhanced crystallization of PVK and strong π–π stacking of planar carbazoles inherent to PVK induce more efficient intramolecular charger transfer from PVK to MoS 2 during the annealing process. Annealing‐induced morphological variation was also observed.…”

Vice versa donor acceptor fluorene–ferrocene alternate copolymer: a twisted ribbon for electrical switching

“…11 Selective substitutions by electron donating dialkyl or electron withdrawing dicyano derivative in 9-position of fluorene (Fl) can make these either electronically rich fluorenes or electronically poor fluorenes, respectively. In this consequence, two new conjugated polymers (Scheme 1) where functionalized Fl moieties would serve the role of donor (PFFC-1) and acceptor (PFFC-2) viceversa have been designed to study the oxidation behaviour of Fc of two polymers by common oxidizing agents 12 as well as the switching behaviour of donor-acceptor conjugated polymers that are scarcely seen in the literature 13,14 . In this aspect, we have synthesized fluorene-ferrocene based two donor-acceptor copolymers to explore by their photophysical, morphological, cyclic voltammetry and electrical behaviours supported by theoretical studies.…”