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Spontaneous phase separation of materials is a powerful strategy to generate highly defined 2D nanomorphologies with novel properties and functions. Exemplary are such morphologies in block copolymers or amphiphilic systems, whose formation can be well predicted based on parameters such as volume fraction and shape factor. In contrast, the formation of 2D nanomorphologies is currently unpredictable in materials perfectly defined at the molecular level, in which crystallinity plays a significant role. Here, we introduce a crystal lattice analysis to predict a priori the formation of 2D nanomorphologies from the crystalline units in phase-separated soft materials. We show that the formation of lamellar morphologies, their domain spacings, and thermal transition temperatures of such materials can be predicted using a straightforward crystal lattice analysis workflow. We envision this approach to facilitate the design and discovery of new materials with 2D nanomorphologies that are essential for next-generation electronic applications.

Efficient energy transport over long distances is essential for optoelectronic and light-harvesting devices. Although self-assembled nanofibers of organic molecules are shown to exhibit long exciton diffusion lengths, alignment of these nanofibers into films with large, organized domains with similar properties remains a challenge. Here, it is shown how the functionalization of C 3 -symmetric carbonyl-bridged triarylamine trisamide (CBT) with oligodimethylsiloxane (oDMS) side chains of discrete length leads to fully covered surfaces with aligned domains up to 125 × 70 µm 2 in which long-range exciton transport takes place. The nanoscale morphology within the domains consists of highly ordered nanofibers with discrete intercolumnar spacings within a soft amorphous oDMS matrix. The oDMS prevents bundling of the CBT fibers, reducing the number of defects within the CBT columns. As a result, the columns have a high degree of coherence, leading to exciton diffusion lengths of a few hundred nanometers with exciton diffusivities (≈0.05 cm 2 s -1 ) that are comparable to those of a crystalline tetracene. These findings represent the next step toward fully covered surfaces of highly aligned nanofibers through functionalization with oDMS., (© 2023 The Authors. Advanced Materials published by Wiley-VCH GmbH.)

The assembly of donor-acceptor molecules via charge transfer (CT) interactions gives rise to highly ordered nanomaterials with appealing electronic properties. Here, we present the synthesis and bulk co-assembly of pyrene (Pyr) and naphthalenediimide (NDI) functionalized oligodimethylsiloxanes (oDMS) of discrete length. We tune the donor-acceptor interactions by connecting the pyrene and NDI to the same oligomer, forming a heterotelechelic block molecule (NDI-oDMSPyr), and to two separate oligomers, giving Pyr and NDI homotelechelic block molecules (Pyr-oDMS and NDI-oDMS). Liquid crystalline materials are obtained for binary mixtures of Pyr-oDMS and NDI-oDMS, while crystallization of the CT dimers occurred for the heterotelechelic NDI-oDMS-Pyr block molecule. The synergy between crystallization and phase-segregation coupled with the discrete length of the oDMS units allows for perfect order and sharp interfaces between the insulating siloxane and CT layers composed of crystalline CT dimers. We were able to tune the lamellar domain spacing and donor-acceptor CT interactions by applying pressures up to 6 GPa on the material, making the system promising for soft-material nanotechnologies. These results demonstrate the importance of the molecular design to tune the CT interactions and stability of a CT material.

Materials based on the laminar ordering of self-assembled molecules have a unique potential for applications requiring efficient energy migration through densely packed chromophores. Here, employing molecular assemblies of coil-rod-coil block molecules for triplet-triplet annihilation upconversion (TTA-UC) based on triplet energy migration with linearly polarized emission is reported. By covalently attaching discrete-length oligodimethylsiloxane (oDMS) to 9,10-diphenylanthracene (DPA), highly ordered 2D crystalline DPA sheets separated by oDMS layers are obtained. Transparent films of this material doped with small amounts of triplet sensitizer Pt II octaethylporphyrin show air-stable TTA-UC under non-coherent excitation. Upon annealing, an increase in TTA-UC up to two orders of magnitude is observed originating from both an improved molecular ordering of DPA and an increased dispersion of the sensitizer. The molecular alignment in millimeter-sized domains leads to upconverted linearly polarized emission without alignment layers. By using a novel technique, upconversion imaging microscopy, the TTA-UC intensity is spatially resolved on a micrometer scale to visually demonstrate the importance of molecular dispersion of sensitizer molecules for efficient TTA-UC. The reported results are promising for anti-counterfeiting and 3D night-vision applications, but also exemplify the potential of discrete oligodimethylsiloxane functionalized chromophores for highly aligned and densely packed molecular materials., (© 2020 The Authors. Advanced Materials published by Wiley-VCH GmbH.)

The scope and accessibility of sequence-controlled multiblock copolymers is demonstrated by direct "in situ" polymerization of hydrophobic, hydrophilic and fluorinated monomers. Key to the success of this strategy is the ability to synthesize ABCDE, EDCBA and EDCBABCDE sequences with high monomer conversions (>98 %) through iterative monomer additions, yielding excellent block purity and low overall molar mass dispersities (Ð<1.16). Small-angle X-ray scattering showed that certain sequences can form well-ordered mesostructures. This synthetic approach constitutes a simple and versatile platform for expanding the availability of tailored polymeric materials from readily available monomers., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Crystallinity is seldomly utilized as part of the microphase segregation process in ultralow-molecular-weight block copolymers. Here, we show the preparation of two types of discrete, semicrystalline block co-oligomers, comprising an amorphous oligodimethylsiloxane block and a crystalline oligo-l-lactic acid or oligomethylene block. The self-assembly of these discrete materials results in lamellar structures with unforeseen uniformity in the domain spacing. A systematic introduction of dispersity reveals the extreme sensitivity of the microphase segregation process toward chain length dispersity in the crystalline block.

The dynamic regulation of circularly polarized luminescence (CPL) holds profound significance in various fields, such as high-level information storage and encryption. Here we developed a chiral amphiphilic molecule, CPSB-GLU-PEG350 (CGP), composed of aggregation-induced emission (AIE) chromophores (Z)-4-(1-cyano-2-phenylvinyl)benzoic acid (CPSB), a chiral linker Glutamic acid and polyethylene glycol (PEG) thermoresponsive segments. Within the self-assembled supramolecular system formed by CGP, we have achieved in-situ temperature-responsive chiral structures, facilitating the thermal control switch of the CPL signal. Molecular dynamics simulations demonstrate the distinct behaviors of AIE and PEG units during the temperature-variable assembly process. Furthermore, by co-assembling achiral dye molecules with CGP, we have expanded the color range of the temperature-responsive CPL assembly system in situ and confirmed the occurrence of circularly polarized-Förster resonance energy transfer (C-FRET) phenomenon in this process, which successfully enriched the strategies for in-situ CPL control in aqueous phases. In addition, the contactless radiative energy transfer of CPL can also be realized in this system, exhibiting more flexible temperature regulation of the CPL signal. This study provides a convenient and universal strategy for the construction of dynamically smart chiroptical materials. [ABSTRACT FROM AUTHOR]

Block copolymers (BCPs) with high Flory-Huggins parameter (χ) and balanced surface energy have aroused tremendous interest for ultra-small nanopatterns processing. However, high χ and balanced surface energy are generally contradicted. The fine tune of chain structure might be a useful way to achieve high χ and balanced surface energy. To realize this, the block copolymer with exactly uniform chain structure, i.e., defined molecular structure, is highly desirable for accurately evaluating the phase behavior. Herein, two kinds of discrete oligo ester-b-oligo olefin block copolymers with different chemical structures (oligo lactic acid-b-oligo olefin BCP, oLAn-b-Cm; oligo phenyl lactic acid-b-oligo olefin BCP, oPLn-b-Cm) were modularly synthesized through iterative growth methods. The effect of chain structure on segregation strength and surface properties was quantitatively investigated using the discrete BCPs as precise models. On the one hand, introducing rigid and nonpolar phenyl groups into oligo ester block has a negligible effect on the chemical incompatibility, as confirmed by the identical high χ values of oLAn-b-Cm and oPLn-b-Cm (χoLA/C = 0.21 and χoPL/C = 0.19). On the other hand, the incorporation of nonpolar phenyl groups creates balanced surface energy, that is, the high χ and balanced surface energy were simultaneously achieved by oPLn-b-Cm. Therefore, sub −10 nm perpendicular nanopatterns can be easily produced upon brief thermal treatment, demonstrating its potential application in semiconductor manufacturing with ultra-small feature size. The discrete BCP can serve as a quantitative and exquisite model to study the critical contribution of chain structures on phase separation behavior, providing insightful understanding to facilitate the potential application in the chip process. [ABSTRACT FROM AUTHOR]

We synthesized a fluorene‐bithiophene co‐polymer with chiral side chains (cPFT2) and investigated its chiroptical properties via synchotronradiation circular dichroism. We observed that thin films of the polymer display an intense circular dichroism (CD) upon annealing, which is of opposite handedness to the CD reported for similar polyfluorenes bearing the same enantiomeric chiral side chain. We then contrast the properties of this polymer with chiral side chain fluorene homopolymer (cPF) and observe large differences in their thin film morphology. Using photoluminescence spectroscopy, we uncover evidence of polymer chain bending in cPFT2, which is further supported by theoretical calculations, and propose an explanation for the observed inverted optical activity. [ABSTRACT FROM AUTHOR]

Chiral B,N-doped polycyclic aromatic hydrocarbons with circularly polarized luminescence (CPL) and small full-width at half-maxima (FWHM) are promising multiple resonance (MR) emitters for CP organic light-emitting diodes (CP-OLEDs). This work presents a pair of chiral MR enantiomers, P/M-o[B-N]2N2, featuring B-N bonds incorporated within a [7]-helicene skeleton. These enantiomers exhibit narrow 0–0 and 0–1 electronic transition bands, whose relative intensity can be fine-tuned by increasing doping concentrations, resulting in redshifts of the emission peak from 542 to 592 nm. The enantiomers show mirror-symmetric CPL spectra with an asymmetry factor (∣gPL∣) of 1.0 × 10−3. The hyperfluorescent CP-OLEDs with double-sensitized emitting layers display a FWHM of 33 nm, an external quantum efficiency of 25.1%, and a ∣gEL∣ factor of 7.7 × 10−4. Notably, the CP-OLEDs realize color-tunable CP electroluminescence peak from 553 to 613 nm by regulating the vibrational coupling. This work provides a novel concept for the design of helical CP-MR materials and CP-OLEDs, highlighting their potential for future applications in advanced optoelectronic devices. [ABSTRACT FROM AUTHOR]

Lewis pair polymerization (LPP) has demonstrated its unique advantages, such as high activity, high stability, and adjustable variability, towards the polymerization of (meth)acrylate monomers in comparison with the other polymerization techniques. The combination of Lewis acid (LA) and Lewis base (LB) to construct Lewis pairs (LPs) with appropriate Lewis basicity, Lewis acidity, and steric effects would significantly impact the polymerization process, including chain initiation, propagation, termination and chain transfer reaction, as well as polymerization manner of monomers. In this feature article, we briefly review recent progress made by our research group towards the living/controlled polymerization of (meth)acrylate monomers, which were accomplished by a series of newly designed LPs, including monofunctional LPs, dual-initiating LPs and intramolecular tethered trifunctional LP. This article is divided into three parts: (1) the development of monofunctional living/controlled LP polymerization system; (2) the design and preparation of dual-initiating LPs in synthesizing thermoplastic elastomers; (3) the application of intramolecular trifunctional LP to the synthesis of cyclic polymers. These developed LPPs have demonstrated their powerful capability in precise control over the molecular weight, molecular weight distribution, and monomer sequence as well as the topology of polymers. This review will serve as a good resource or guideline for researchers currently working in the area of LPP and for those who are interested in synthesizing new materials by LPP. [ABSTRACT FROM AUTHOR]

The research in circularly polarized luminescence has attracted wide interest in recent years. Efforts on one side are directed toward the development of chiral materials with both high luminescence efficiency and dissymmetry factors, and on the other side, are focused on the exploitations of these materials in optoelectronic applications. This review summarizes the recent frontiers (mostly within five years) in the research in circularly polarized luminescence, including the development of chiral emissive materials based on organic small molecules, compounds with aggregation-induced emissions, supramolecular assemblies, liquid crystals and liquids, polymers, metal-ligand coordination complexes and assemblies, metal clusters, inorganic nanomaterials, and photon upconversion systems. In addition, recent applications of related materials in organic light-emitting devices, circularly polarized light detectors, and organic lasers and displays are also discussed. [ABSTRACT FROM AUTHOR]