Hierarchical Helical Assembly of Conjugated Poly(3-hexylthiophene)-block-poly(3-triethylene glycol thiophene) Diblock Copolymers

Morphology Control and Spectral Study of the 2D and Hierarchical Nanostructures Self-Assembled by the Chiral Alanine-Decorated Perylene Bisimides

Tailoring the morphologies and optical properties of the 2D and hierarchical nanostructures self-assembled by the π-conjugated molecules is both interesting and challenging. Herein, a series of 2D ribbon-like nanostructures with single or multiple H-aggregated perylene bisimides (PBI) monolayer and hierarchical nanostructures (including straw-like, dumbbell-shaped, and rod-like nanostructures) are fabricated by solution self-assembly of three chiral alanine-decorated PBI. The influence of the solvent's dissolving capacity, the chirality of alanine, and the preparation methods on the morphologies and optical properties of the nanostructures were extensively studied. It was observed that the hierarchical nanostructures are formed by the reorganization of the 2D ribbon-like nanostructures. The size of the 2D ribbon-like nanostructures and the amount of the hierarchical nanostructures increase with the decrease in the solvent's dissolving capacity. The small chiral alanine moiety is unable to induce chirality in the nanostructures, owing to its low steric hindrance and the dominant strong π-π stacking interaction of the PBI skeleton. A weaker π-π stacking interaction and better H-aggregated arrangement of the PBI skeleton could reduce the low-wavelength fluorescence intensity. The process of heating, cooling, and aging promotes the formation of H-aggregation in the PBI skeleton. The region of spectral overlap of the PBI solutions increases with the decrease in the dissolving capacity of the solvent and the steric hindrance of the chiral alanine. This study supplies a view to tailor the morphologies and optical properties of the nanostructures, which could be used as sensors and photocatalysts.

Coplanar Conformational Structure of π-Conjugated Polymers for Optoelectronic Applications

Hierarchical structure of conjugated polymers is critical to dominating their optoelectronic properties and applications. Compared to nonplanar conformational segments, coplanar conformational segments of conjugated polymers (CPs) demonstrate favorable properties for applications as a semiconductor. Herein, recent developments in the coplanar conformational structure of CPs for optoelectronic devices are summarized. First, this review comprehensively summarizes the unique properties of planar conformational structures. Second, the characteristics of the coplanar conformation in terms of optoelectrical properties and other polymer physics characteristics are emphasized. Five primary characterization methods for investigating the complanate backbone structures are illustrated, providing a systematical toolbox for studying this specific conformation. Third, internal and external conditions for inducing the coplanar conformational structure are presented, offering guidelines for designing this conformation. Fourth, the optoelectronic applications of this segment, such as light-emitting diodes, solar cells, and field-effect transistors, are briefly summarized. Finally, a conclusion and outlook for the coplanar conformational segment regarding molecular design and applications are provided.

Sequence effect on the self-assembly of discrete amphiphilic co-oligomers with fluorene-azobenzene semirigid backbones

Sequences can have a dramatic impact on the unique properties and self-assembly in natural macromolecules, which has received increasing interest. Herein, we report a series of discrete amphiphilic co-oligomers with the same composition but different building blocks in a semirigid backbone. These sequence-defined oligomers possess two primary amine groups on the side chain of the azobenzene building block, and hence, they become amphipathic due to quaternization of the amine groups when protonated in acidic aqueous solution. These oligomer isomers assembled into different nanoparticles, including nanofibers, hollow vesicles and spherical micellar complexes, in a THF/water/HCl mixture under the same conditions. UV-vis absorption spectra, differential scanning calorimetry (DSC) and X-ray scattering (XRD) experiments combined with theoretical calculations reveal that the sequence-controlled co-oligomers induce different molecular packing conformations and arrangement modes of building blocks in self-assembly. Furthermore, these self-assembled nanoparticles demonstrate photoresponsive morphological transformation and fluorescence emission under UV light irradiation due to trans-to-cis photoisomerization of azobenzene. This work demonstrates that customizing functional nanoparticles can be achieved by controlling the sequence structure in synthetic co-oligomers.

Insight into Unusual Supramolecular Self-Assemblies of Terthiophenes Directed by Weak Hydrogen Bonding

A supramolecular self-assembly of semiconducting polymers and small molecules plays an important role in charge transportation, performance, and lifetime of an optoelectronic device. Tremendous efforts have been put into the strategies to self-organize these materials. In this regard, here, we present the self-organization of terthiophene and its methyl alcohol derivative with 4,4'-bipyridine (44BiPy). An unexpected 2D layered organization of 5,5″-dimethyl-2,2':5',2″-terthiophene (DM3T) and 44BiPy was obtained and analyzed. Single-crystal X-ray diffraction analysis revealed that DM3T and 44BiPy consist of stacked, almost independent, infinite 2D layers while held together by weak hydrogen bonds. In addition to this peculiar supramolecular arrangement of these compounds, the investigation of their photophysical properties showed strong fluorescence quenching of DM3T by 44BiPy in the solid state, suggesting an efficient charge transfer. On the other hand, the methyl alcohol derivative of terthiophene, DM3TMeOH, organized in a closed cyclic motif with 44BiPy via hydrogen bonds.

Seeded-growth self-assembled polymerization of a ferrocene-bearing palladium(II)-terpyridyl bimetallic complex

A new bimetallic complex containing a 4'-ferrocenyl-(2,2':6',2''-terpyridine)palladium core with polyethylene glycol-based pyridine is applied in seeded-growth self-assembled supramolecular polymerization, which affords nanoribbons with controllable lengths and the process follows a first-order reaction kinetics. This approach is successfully demonstrated for a bimetallic organic complex for the first time.

Conjugated Block Copolymers for Functional Nanostructures

Conjugated polymers have been actively studied as an alternative to inorganic semiconductors for their unique optical and electrical properties and low-cost solution processability. However, typical conjugated polymer films contain numerous defects that negatively affect their transport properties, which remains a major issue despite much effort to develop ways to improve the molecular packing structure. In principle, conjugated block copolymers (BCPs) composed of a rod-type conjugated polymer and a coil-type insulating polymer can assemble into various types of ordered nanostructures based on the microphase segregation of two polymer blocks. However, such assembly typically requires a relatively large volume fraction of the coil block or modification of the rod block, both of which tend to impede charge transport. As an alternative, we and others have fabricated nanoscale assemblies of conjugated BCPs via solution-phase self-assembly, which can be used as building blocks for construction of extended nanoarrays of conjugated polymers. In particular, BCPs containing poly(3-hexylthiophene) (P3HT), a conjugated polymer widely used for its high hole mobility, form highly ordered and technologically relevant one-dimensional (1D) nanowires with controlled lengths. A range of well-defined assembly structures such as square plates, ribbons, vesicles, and helices have been prepared from various conjugated BCPs, resembling those of peptide self-assembly, forming diverse nanostructures through combinations of π-π stacking, hydrogen bonding, and hydrophobic interactions.When the self-assembly of P3HT BCPs takes place at an air-water interface, the initially formed polymer nanowires further assemble into hierarchical two-dimensional (2D) nanoarrays with solvent evaporation. The fluidic nature of the water subphase allows fabrication of highly ordered assembly structures from P3HT BCPs with high P3HT content. The ultrathin free-standing film integrated in a field effect transistor (FET) showed orders of magnitude higher current and hole mobility compared to that fabricated by conventional spin-coating. Furthermore, binary self-assembly of a P3HT BCP and quantum dots (QDs) at the air-water interface generates well-ordered 2D films of alternating P3HT nanowires and 1D QD arrays. Unlike coil-coil BCP systems, QDs reside at the interface between P3HT and coil blocks for a broad range of QD sizes due to the strong P3HT packing interactions and the flexible water subphase, forming tight p-n junctions for enhanced photocurrent. Incorporation of magnetic nanoparticles can further improve the degree of order, enabling fabrication of long-range order and direction-controlled P3HT nanoarrays through magnetic-field induced self-assembly.The conjugated BCP approach is highly modular and can be combined with various types of functional molecules, polymers, and nanoparticles, offering a powerful platform for fabrication of functional polymer nanostructures with desired morphologies and properties. This Account introduces recent advances in the self-assembly of π-conjugated BCPs, describes how they differ from prototypical coil-coil type BCPs, and discusses current issues and future outlooks.

One-Dimensional Helical Nanostructures from the Hierarchical Self-Assembly of an Achiral "Rod-Coil" Alternating Copolymer

The self-assembly of alternating copolymers (ACPs) has attracted considerable interest due to their unique alternating nature. However, compared with block copolymers, their self-assembly behavior has remained much less explored and their reported self-assembled structures are limited. Here, we report the formation of supramolecular helical structures by the self-assembly of an achiral rod-coil alternating copolymer, poly(quarter(3-hexylthiophene)-alt-poly(ethylene glycol)) (P(Q3HT-alt-PEG)). The copolymer exhibited an interesting hierarchical self-assembly process, driven by the π-π stacking of the Q3HT segments and the solvophobic interaction of the alkyl chains in tetrahydrofuran (THF)-isopropanol (iPrOH) mixed solvents. The copolymer first self-assembled into thin nanobelts with a uniform size, then grew to helical nanoribbons and eventually twisted into helical nanowires with an average diameter of 25 ± 9 nm and a mean pitch of 80 ± 10 nm. Dissipative particle dynamics (DPD) simulation supported the formation course of the helical nanowires. Furthermore, the addition of (S)-ethyl lactate and (R)-ethyl lactate in the self-assembly of P(Q3HT-alt-PEG) resulted in the formation of left-handed and right-handed chiral nanowires, respectively, demonstrating the tunability of the chirality of the helical wires. This study expands the library of ordered self-assembled structures of ACPs, and also brings a new strategy and mechanism to construct helical supramolecular structures. This article is protected by copyright. All rights reserved.

Using Gamification to Facilitate Students’ Self-Regulation in E-Learning: A Case Study on Students’ L2 English Learning

E-learning has been an important learning approach in the information era by providing flexible environments and rich resources for learners. However, it also faces several challenges, the biggest one being that students need to have strong self-regulation competence to control and manage their e-learning. As gamification has been widely used in primary education to facilitate children’s learning motivation and engagement, it is valuable to explore the impacts of gamification on children’s self-regulated learning. In this study, the role of gamification in children’s English learning in Hong Kong was investigated through a gamified e-learning system. A quasi-experiment with pre-test/post-test design was conducted among primary level 3 students over a semester. Both quantitative and qualitative data were gathered through academic tests, questionnaires, and interviews to provide comprehensive insights into the research questions. The key findings enable the identification of: (1) students’ gaining of self-regulated learning interest and academic performance from the gamified learning system; (2) students’ developed self-regulated learning strategies; and (3) the connection between gamification and students’ self-regulated learning. These findings have implications for e-learning designers and educators with regards to the practice of gamified learning to enhance students’ self-regulated learning and second language learning.

Facile synthesis of water-dispersible poly(3-hexylthiophene) nanoparticles with high yield and excellent colloidal stability

There has been growing interest in water-processable conjugated polymers for biocompatible devices. However, some broadly used conjugated polymers like poly(3-hexylthiophene) (P3HT) are hydrophobic and they cannot be processed in water. We herein report a facile yet highly efficient assembly method to prepare water-dispersible pyridine-containing P3HT (Py-P3HT) nanoparticles (NPs) with a high yield (>80%) and a fine size below 100 nm. It is based on the fast nanoprecipitation of Py-P3HT stabilized by hydrophilic poly(acrylic acid) (PAA). Py-P3HT can form spherical NPs at a concentration up to 0.2 mg/mL with a diameter of ∼75 nm at a very low concentration of PAA, e.g., 0.01-0.1 mg/mL, as surface ligands. Those negatively charged Py-P3HT NPs can bind with metal cations and further support the growth of noble metal NPs like Ag and Au. Our self-assembly methodology potentially opens new doors to process and directly use hydrophobic conjugated polymers in a much broader context.

Self-Assembly of Copolymers Containing Crystallizable Blocks: Strategies and Applications

The self-assembly of copolymers containing crystallizable block in solution has received increasing attentions in the past few years. Various strategies including crystallization-driven self-assembly (CDSA) and polymerization-induced CDSA (PI-CDSA) have been widely developed. Abundant self-assembly morphologies were captured and advanced applications have been attempted. In this review, the synthetic strategies including the mechanisms and characteristics are highlighted, the survey on the advanced applications of crystalline nano-assemblies are collected. This review is hoped to depict a comprehensive outline for self-assembly of copolymers containing crystallizable block in recent years and to prompt the development of the self-assembly technology in interdisciplinary field. This article is protected by copyright. All rights reserved.

Precrystalline P3HT nanowires: growth-controllable solution processing and effective molecular packing transfer to thin-film

Solution-processable precrystalline nanowires (NWs) of conjugated polymers (CPs) have garnered significant attention in fundamental research based on crystallization-driven self-assembly and in the roll-to-roll fabrication of optoelectronic devices such as organic...

Mechanical properties and structures under the deformation of thiophene copolymers with cyclic siloxane units

The control of cross-linking of polythiophene with cyclic siloxane was achieved and provided to their mechanical properties and elastic recovery. The cross-links led to high recovery of crystallite orientation under stretching.

Precision Synthesis of Conjugated Polymers Using the Kumada Methodology

Since the discovery of conductive poly(acetylene), the study of conjugated polymers has remained an active and interdisciplinary frontier between polymer chemistry, polymer physics, computation, and device engineering. One of the ultimate goals of polymer science is to reliably synthesize structures, similar to small molecule synthesis. Kumada catalyst-transfer polymerization (KCTP) is a powerful tool for synthesizing conjugated polymers with predictable molecular weights, narrow dispersities, specific end groups, and complex backbone architectures. However, expanding the monomer scope beyond the well-studied 3-alkylthiophenes to include electron-deficient and complex heterocycles has been difficult. Revisiting the successful applications of KCTP can help us gain new insight into the CTP mechanisms and thus inspire breakthroughs in the controlled polymerization of challenging π-conjugated monomers.In this Account, we highlight our efforts over the past decade to achieve controlled synthesis of homopolymers (p-type and n-type), copolymers (diblock and statistical), and monodisperse high oligomers. We first give a brief introduction of the mechanism and state-of-the-art of KCTP. Since the extent of polymerization control is determined by steric and electronic effects of both the catalyst and monomer, the polymerization can be optimized by modifying monomer and catalyst structures, as well as finding a well-matched monomer-catalyst system. We discuss the effects of side-chain steric hindrance and halogens in the context of heavy atom substituted monomers. By moving the side-chain branch point one carbon atom away from the heterocycle to alleviate steric crowding and stabilize the catalyst resting state, we were able to successfully control the polymerization of new tellurophene monomers. Inspired by innocent role of the sterically encumbered 2-transmetalated 3-alkylthiophene monomer, we introduce the treatment of hygroscopic monomers with a bulky Grignard compound as a water-scavenger for the improved synthesis of water-soluble conjugated polymers. For challenging electron-deficient monomers, we discuss the design of new Ni(II)diimine catalysts with electron-donating character which enhance the stability of the association complex between the catalyst and the growing polymer chain, resulting in the quasi-living synthesis of n-type polymers. Beyond n-type homopolymers, the Ni(II)diimine catalysts are also capable of producing electron-rich and electron-deficient diblock and statistical copolymers. We discuss how density functional theory (DFT) calculations elucidate the role of catalyst steric and electronic effects in controlling the synthesis of π-conjugated polymers. Moreover, we demonstrate the synthesis of monodisperse high oligomers by temperature cycling, which takes full advantage of the unique character of KCTP in that it proceeds through distinct intermediates that are not reactive. The insight we gained thus far leads to the first example of isolated living conjugated polymer chains prepared by a standard KCTP procedure, with general applicability to different monomers and catalytic systems. In summarizing a decade of innovation in KCTP, we hope this Account will inspire future development in the field to overcome key challenges including the controlled synthesis of electron-deficient heterocycles, complex and high-performance systems, and degradable and recyclable materials as well as cutting-edge catalyst design.

Thiophene- and selenophene-based conjugated polymeric mixed ionic/electronic conductors

Mixed ionic/electronic conductors (MIECs) are desirable materials for next-generation electronic devices and energy storage applications. Polymeric MIECs are attractive from the standpoint that their structure can be controlled and anticipated to have mechanically robust properties. Here, we prepare and investigate conjugated copolymers containing thiophene and selenophene repeat units and their homopolymer counterparts. Specifically, thiophene bearing a triethylene glycol (EG₃) side chain was polymerized and copolymerized with dodecyl thiophene/selenophene monomers. The synthesis leads to a class of copolymers that contain either S or Se and are blocky in nature. The Li-ion conductivity of ionically doped copolymers, P3DDT-s-P3(EG₃)T and P3DDS-s-P3(EG₃)T (9.7 × 10^-6 and 8.2 × 10^-6 S/cm, respectively), was 3-4 fold higher than that of the ionically doped constituent homopolymer, P3(EG₃)T (2.2 × 10^-6 S/cm), at ambient conditions. The electronic conductivity of the oxidatively doped copolymers was significantly higher than that of the constituent homopolymer P3(EG₃)T, and most notably, P3DDS-s-P3(EG₃)T reached ∼7 S/cm, which is the same order of magnitude as poly(3-dodecylthiophene) and poly(3-dodecylselenophene), which are the highest oxidatively doped conductors based on control experiments. Our findings provide implications for designing new MIECs based on copolymerization and the incorporation of heavy atom heterocycles.

3,4-Ethylenedioxythiophene (EDOT) End-Group Functionalized Poly-ε-caprolactone (PCL): Self-Assembly in Organic Solvents and Its Coincidentally Observed Peculiar Behavior in Thin Film and Protonated Media

End-group functionalization of homopolymers is a valuable way to produce high-fidelity nanostructured and functional soft materials when the structures obtained have the capacity for self-assembly (SA) encoded in their structural details. Herein, an end-functionalized PCL with a π-conjugated EDOT moiety, (EDOT-PCL), designed exclusively from hydrophobic domains, as a functional "hydrophobic amphiphile", was synthesized in the bulk ROP of ε-caprolactone. The experimental results obtained by spectroscopic methods, including NMR, UV-vis, and fluorescence, using DLS and by AFM, confirm that in solvents with extremely different polarities (chloroform and acetonitrile), EDOT-PCL presents an interaction- and structure-based bias, which is strong and selective enough to exert control over supramolecular packing, both in dispersions and in the film state. This leads to the diversity of SA structures, including spheroidal, straight, and helical rods, as well as orthorhombic single crystals, with solvent-dependent shapes and sizes, confirming that EDOT-PCL behaves as a "block-molecule". According to the results from AFM imaging, an unexpected transformation of micelle-type nanostructures into single 2D lamellar crystals, through breakout crystallization, took place by simple acetonitrile evaporation during the formation of the film on the mica support at room temperature. Moreover, EDOT-PCL's propensity for spontaneous oxidant-free oligomerization in acidic media was proposed as a presumptive answer for the unexpected appearance of blue color during its dissolution in CDCl3 at a high concentration. FT-IR, UV-vis, and fluorescence techniques were used to support this claim. Besides being intriguing and unforeseen, the experimental findings concerning EDOT-PCL have raised new and interesting questions that deserve to be addressed in future research.

Improving the Kumada Catalyst Transfer Polymerization with Water-Scavenging Grignard Reagents

Conjugated polymers have received widespread interest as optoelectronic materials. Recently, these macromolecules have been adopted for biologically relevant applications, such as sensors, imaging agents, and drug delivery vectors. A major limitation of the chemistry used to prepare these classes of compounds is that the resultant polymers themselves are not tolerant to water or are not inherently water-soluble. For example, the most controlled method of conjugated polymer synthesis, the Kumada catalyst transfer polymerization (KCTP), requires stringent drying of monomers, catalysts, and other reagents. Here, we describe an approach to use a water-scavenging Grignard reagent to alleviate many of the shortcomings that currently hinder the synthesis of water-soluble conjugated polymers. This method shows improved polymerization performance in both traditional conjugated polymer synthesis as well as more challenging syntheses of polar hygroscopic polymers that are of interest for biological applications.

Smart supramolecular nanofibers and nanoribbons from uniform amphiphilic azobenzene oligomers

A series of self-assembled 1D nanostructures, including straight and helix nanofibers, nanoribbons, and nanobelts, were fabricated from uniform amphiphilic azobenzene oligomers with tunable molecular weight and side chain functionality, promoted by multiple and cooperative supramolecular interactions. Additionally, the morphological transformation of the nanofibers was achieved during the photoisomerization process.

Emerging applications for living crystallization-driven self-assembly

The use of crystallization as a tool to control the self-assembly of polymeric and molecular amphiphiles in solution is attracting growing attention for the creation of non-spherical nanoparticles and more complex, hierarchical assemblies. In particular, the seeded growth method termed living crystallization-driven self-assembly (CDSA) has been established as an ambient temperature and potentially scalable platform for the preparation of low dispersity samples of core-shell fiber-like or platelet micellar nanoparticles. Significantly, this method permits predictable control of size, and access to branched and segmented structures where functionality is spatially-defined. Living CDSA operates under kinetic control and shows many analogies with living chain-growth polymerizations of molecular organic monomers that afford well-defined covalent polymers of controlled length except that it covers a much longer length scale (ca. 20 nm to 10 μm). The method has been applied to a rapidly expanding range of crystallizable polymeric amphiphiles, which includes block copolymers and charge-capped homopolymers, to form assemblies with crystalline cores and solvated coronas. Living CDSA seeded growth methods have also been transposed to a wide variety of π-stacking and hydrogen-bonding molecular species that form supramolecular polymers in processes termed "living supramolecular polymerizations". In this article we outline the main features of the living CDSA method and then survey the promising emerging applications for the resulting nanoparticles in fields such as nanomedicine, colloid stabilization, catalysis, optoelectronics, information storage, and surface functionalization.

Cocrystallization-Promoted Charge Mobility in All-Conjugated Diblock Copolymers for High-Performance Field-Effect Transistors

The cocrystallization method that combines various constituents into cocrystals yields the newly formed materials with significantly enhanced charge transport properties. However, this strategy has not been greatly utilized in all-conjugated block copolymers (BCPs). Herein, we scrutinize the relationship between cocrystals and charge mobilities in all-conjugated BCPs (i.e., poly(3-butylthiophene)-block-poly(3-hexylthiophene); denoted P3BT-b-P3HT) by tuning their molecular weights and thermal annealing process. All the rod-rod BCPs form cocrystals with high charge mobilities than P3BT and P3HT homopolymers and P3BT/P3HT blend, imparting the cocrystal-facilitated charge transport because of the synergy of two conjugated components. Upon 150 °C treatment, their crystallinities increase and their charge mobilities at 15k, 18k, and 28k increase slightly. In contrast, P3BT-b-P3HT-12k shows decreased charge mobilities. It is due to the preferential increase of crystal size and order through the π-π stacking direction in the former while through the alkyl stacking direction in the latter. Intriguingly, when these P3BT-b-P3HT cocrystals experience two-step thermal treatment, P3BT-b-P3HT-12k retains its cocrystalline structure, while microphase separation of P3BT and P3HT occurs in P3BT-b-P3HT-15k, 18k, and 28k with different degrees. All P3BT-b-P3HT BCPs exhibit decreased charge mobilities. This study demonstrates the cocrystallization-promoted charge mobility in all-conjugated BCPs, which may facilitate their application in a wide range of optoelectronic devices.

Seeded Self-Assembly of Charge-Terminated Poly(3-hexylthiophene) Amphiphiles Based on the Energy Landscape

The creation of 1D π-conjugated nanofibers with precise control and optimized optoelectronic properties is of widespread interest for applications as nanowires. "Living" crystallization-driven self-assembly (CDSA) is a seeded growth method of growing importance for the preparation of uniform 1D fiber-like micelles from a range of crystallizable polymeric amphiphiles. However, in the case of polythiophenes, one of the most important classes of conjugated polymer, only limited success has been achieved to date using block copolymers as precursors. Herein, we describe studies of the living CDSA of phosphonium-terminated amphiphilic poly(3-hexylthiophene)s to prepare colloidally stable nanofibers. In depth studies of the relationship between the degree of polymerization and the self-assembly behavior permitted the unveiling of the energy landscape of the living CDSA process. On the basis of the kinetic and thermodynamic insight provided, we have been able to achieve an unprecedented level of control over the length of low dispersity fiber-like micelles from 40 nm to 2.8 μm.

Hybrid conjugated polymer/magnetic nanoparticle composite nanofibers through cooperative non-covalent interactions

Hybrid organic-inorganic composites possessing both electronic and magnetic properties are promising materials for a wide range of applications. Controlled and ordered arrangement of the organic and inorganic components is key for synergistic cooperation toward desired functions. In this work, we report the self-assemblies of core-shell composite nanofibers from conjugated block copolymers and magnetic nanoparticles through the cooperation of orthogonal non-covalent interactions. We show that well-defined core-shell conjugated polymer nanofibers can be obtained through solvent induced self-assembly and polymer crystallization, while hydroxy and pyridine functional groups located at the shell of nanofibers can immobilize magnetic nanoparticles via hydrogen bonding and coordination interactions. These precisely arranged nanostructures possess electronic properties intrinsic to the polymers and are simultaneously responsive to external magnetic fields. We applied these composite nanofibers in organic solar cells and found that these non-covalent interactions led to controlled thin film morphologies containing uniformly dispersed nanoparticles, although high loadings of these inorganic components negatively impact device performance. Our methodology is general and can be utilized to control the spatial distribution of functionalized organic/inorganic building blocks, and the magnetic responsiveness and optoelectronic activities of these nanostructures may lead to new opportunities in energy and electronic applications.

Formal preparation of regioregular and alternating thiophene-thiophene copolymers bearing different substituents

Differently substituted thiophene–thiophene-alternating copolymers were formally synthesized employing a halo-bithiophene as a monomer. Nickel-catalyzed polymerization of bithiophene with substituents at the 3-position, including alkyl-, fluoroalkyl-, or oligosiloxane-containing groups, afforded the corresponding copolymers in good to excellent yield. The solubility test in organic solvents was performed to reveal that several copolymers showed a superior solubility. X-ray diffraction analysis of the thin film of the alternating copolymers composed of methyl and branched oligosiloxane substituents was also performed, and the results suggested the formation of a dual-layered film structure.

Controlling the supramolecular polymerization of dinuclear isocyanide gold(i) arylethynylene complexes through tuning the central π-conjugated moiety

Tuning the middle chromophores of dinuclear gold(i) arylethynyl complexes has been demonstrated to exhibit a pronounced effect on the photophysical properties, self-assembly mechanisms and morphologies.

Improved efficiency of single-component active layer photovoltaics by optimizing conjugated diblock copolymers

Using an A–B type monomer instead of an AA + BB type monomer to synthesise diblock copolymers, the PCE of a single-component photovoltaic device reached 1.22%.

Oligo(ethylene glycol) as side chains of conjugated polymers for optoelectronic applications

Except hydrophobic alkyl side chains, hydrophilic oligo(ethylene glycol) (OEG) has also been used as side chains of conjugated polymers and endow the resulting polymers with interesting properties and excellent opto-electronic device performance.

Manipulation and Deposition of Complex, Functional Block Copolymer Nanostructures Using Optical Tweezers

Block copolymer self-assembly has enabled the creation of a range of solution-phase nanostructures with applications from optoelectronics and biomedicine to catalysis. However, to incorporate such materials into devices a method that facilitates their precise manipulation and deposition is desirable. Herein we describe how optical tweezers can be used to trap, manipulate, and pattern individual cylindrical micelles and larger hybrid micellar materials. Through the combination of TIRF imaging and optical trapping we can precisely control the three-dimensional motion of individual cylindrical block copolymer micelles in solution, enabling the creation of customizable arrays. We also demonstrate that dynamic holographic assembly enables the creation of ordered customizable arrays of complex hybrid block copolymer structures. By creating a program which automatically identifies, traps, and then deposits multiple assemblies simultaneously we have been able to dramatically speed up this normally slow process, enabling the fabrication of arrays of hybrid structures containing hundreds of assemblies in minutes rather than hours.

Rapid solvo-microwave annealing for optimizing ordered nanostructures and crystallization of regioregular polythiophene-based block copolymers

Solvo-microwave annealing is an effective method for producing thin films of polythiophene-based block copolymers with ordered structures and high crystallinity in a very short processing time (∼3 min).

Controlling the supramolecular polymerization and metallogel formation of Pt(ii) complexes via delicate tuning of non-covalent interactions

Direct influence of noncovalent ionic and hydrogen bonding interactions on supramolecular polymerization mechanisms and their impact on gel formation of luminescent platinum complexes have been comprehensively investigated.

Elucidation of the Origin of Thixotropic-Inducing Properties of Additive Amphiphiles and the Creation of a High-Performance Triamide Amphiphile

The spontaneous growth of helical fibers of amphiphilic diamide derivatives containing hydrocarbons with asymmetric carbon centers in their constituent hydrocarbons was investigated. 12-Hydroxystearic acid and a gemini-type surfactant obtained by the bimolecular condensation of this compound with hexamethylenediamine both impart thixotropic ability to a solvent. Although this thixotropic behavior is based on the growth of hierarchical crystalline nanofibers in the solvents, the degree of fiber growth itself was not the origin of the thixotropy. In this study, it has adopted the methods of the Langmuir monolayer and Langmuir-Blodgett films as technique to selectively and individually evaluate the behavior of 12-hydroxyl stearyl and/or stearyl chains themselves. The ability to impart thixotropy to the solvent via fiber organization was related to the intermolecular hydrogen bonding between the added amphiphiles. Additionally, homogeneous right-handed helical fibers were formed in the spin-cast films of the diamide derivatives, and a positive Cotton effect was observed in their circular dichroism spectra. It is suggested that fibers that do not form helical arrangements cannot impart sufficient thixotropy to the solvent even when extensive fiber growth is achieved, and the structure-dependent development of chirality is the driving force. In addition, to further the development of highly functional thixotropic agents, a trefoil-like triamide derivative containing three chains was synthesized. By using this molecule, solvent gelation occurred at 78% as an addition to the diamide case, and a supramolecular assembly was formed in the corresponding two-dimensional film.

Simple Solvent Engineering for High-Mobility and Thermally Robust Conjugated Polymer Nanowire Field-Effect Transistors

Electron donor (D)-acceptor (A)-type conjugated polymers (CPs) have emerged as promising semiconductor candidates for organic field-effect transistors. Despite their high charge carrier mobilities, optimization of electrical properties of D-A-type CPs generally suffers from complicated post-deposition treatments such as high-temperature thermal annealing or solvent-vapor annealing. In this work, we report a high-mobility diketopyrrolopyrrole-based D-A-type CP nanowires, self-assembled by a simple but very effective solvent engineering method that requires no additional processes after film deposition. In situ grown uniform nanowires at room temperature were shown to possess distinct edge-on chain orientation that is beneficial for lateral charge transport between source and drain electrodes in FETs. FETs based on the polymer nanowire networks exhibit impressive hole mobility of up to 4.0 cm² V^-1 s^-1. Moreover, nanowire FETs showed excellent operational stability in high temperature up to 200 °C because of the strong interchain interaction and alignment.

Twisting Ultrathin Au Nanowires into Double Helices

Previously, double helix nanowire was reported by coating Pd/Pt/Au onto Au-Ag alloy nanowire. Here, straight oleylamine-stabilized ultrathin Au nanowires with single crystalline fcc lattice are surprisingly converted into double helix helices upon reacting with Ag in tetrahydrofuran (THF). The obtained Au-Ag helical nanowires contain lattice distinctively different from the fcc lattice and are different in many aspects with the previous system. The discovery may expand the scope of nanoscale double helix formation and the understanding of lattice transformation among ultrafine nanostructures.

Hydrogen-bonding-directed helical nanofibers in a polythiophene-based all-conjugated diblock copolymer

One-dimensional (1D) helical nanofibers were prepared through the self-assembly of an achiral all-conjugated diblock copolymer, poly(3-hexylthiophene)-b-poly[3-(6-hydroxyl)hexylthiophene] (P3HT-b-P3HHT) in an aged pyridine solution. Such helical nanofibers were formed by the π-π interaction between planar rigid polythiophene backbones cooperating with the hydrogen-bonding interactions between the polar hydroxyl groups of the side chains of polythiophenes. Intriguingly, the Young's modulus of such helical fibers is as high as ∼5.16 GPa, which is about twice that of P3HT films characterized by the peak force quantitative nanomechanical (PF-QNM) method. Furthermore, for the first time, we report that such helical fibers based on all-conjugated polythiophenes exhibited a relatively high field-effect mobility of 0.03472 cm2 V-1 s-1. This work provides a promising approach to craft crystalline helical nanostructures based on polythiophenes possessing both superior mechanical and good charge transport properties, which has great potential for application in other π-conjugated systems or building blocks for complex superstructures, and mechanical and optoelectronic devices.