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Chemically resistant and thermally stable quantum dots prepared by shell encapsulation with cross-linkable block copolymer ligands
摘要： Endowing quantum dots (QDs) with robustness and durability have been one of the most important issues in this field, since the major limitations of QDs in practical applications are their thermal and oxidative instabilities. In this work, we propose a facile and effective passivation method to enhance the photochemical stability of QDs using polymeric double shell structures from thiol-terminated poly(methyl methacrylate-b-glycidyl methacrylate) (P(MMA-b-GMA)-SH) block copolymer ligands. To generate a densely cross-linked network, the cross-linking reaction of GMA epoxides in the PGMA block was conducted using a Lewis acid catalyst under an ambient environment to avoid affecting the photophysical properties of the pristine QDs. This provides QDs encapsulated with robust double layers consisting of highly transparent PMMA outer-shell and oxidation-protective cross-linked inner shell. Consequently, the resulting QDs exhibited exceptional tolerance to heat and oxidants when dispersed in organic solvents or QD-nanocomposite films, as demonstrated under various harsh conditions with respect to temperature and oxidant species. The present approach not only provides simple yet effective chemical means to enhance the thermochemical stability of QDs, but also offers a promising platform for the hybridization of QDs with polymeric materials for developing robust light-emitting or light-harvesting devices.
关键词： photochemical stability,block copolymer ligands,oxidative stability,cross-linking,thermal stability,quantum dots
更新于2025-09-23 15:19:57
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Hybrid fluorescent liquid crystalline composites: directed assembly of quantum dots in liquid crystalline block copolymer matrices
摘要： Hybrid ?uorescent liquid crystalline (LC) composites containing inorganic quantum dots (QDs) are promising materials for many applications in optics, nanophotonics and display technology, combining the superior emission capability of QDs with the externally controllable optical properties of LCs. In this work, we propose the hybrid LC composites that were obtained by embedding CdSe/ZnS QDs into a series of host LC block copolymers of di?erent architectures by means of a two-stage ligand exchange procedure. The ABA/BAB triblock copolymers and AB diblock copolymers with di?erent polymerization degrees are composed of nematogenic phenyl benzoate acrylic monomer units and poly(4-vinylpyridine) blocks, which are capable of binding to the QD surface. Our results clearly show that the spatial distribution of QDs within composite ?lms as well as the formation of QD aggregates can be programed by varying the structure of the host block copolymer. The obtained composites form a nematic LC phase, with isotropization temperatures being close to those of the initial host block copolymers. In addition, the in?uence of the molecular architecture of the host block copolymers on ?uorescence properties of the obtained composites is considered. The described strategy for the QD assembly should provide a robust and conventional route for the design of highly ordered hierarchical hybrid materials for many practical applications.
关键词： liquid crystalline block copolymer matrices,ligand exchange procedure,fluorescence properties,CdSe/ZnS QDs,nematic LC phase,Hybrid ?uorescent liquid crystalline composites,quantum dots
更新于2025-09-23 15:19:57
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Comparing blends and blocks: Synthesis of partially fluorinated diblock polythiophene copolymers to investigate the thermal stability of optical and morphological properties
摘要： The microstructure of the active blend layer has been shown to be a critically important factor in the performance of organic solar devices. Block copolymers provide a potentially interesting avenue for controlling this active layer microstructure in solar cell blends. Here we explore the impact of backbone fluorination in block copolymers of poly(3-octyl-4-fluorothiophene)s and poly(3-octylthiophene) (F-P3OT-b-P3OT). Two block co-polymers with varying block lengths were prepared via sequential monomer addition under Kumada catalyst transfer polymerisation (KCTP) conditions. We compare the behavior of the block copolymer to that of the corresponding homopolymer blends. In both types of system, we find the fluorinated segments tend to dominate the UV–visible absorption and molecular vibrational spectral features, as well as the thermal behavior. In the block copolymer case, non-fluorinated segments appear to slightly frustrate the aggregation of the more fluorinated block. However, in situ temperature dependent Raman spectroscopy shows that the intramolecular order is more thermally stable in the block copolymer than in the corresponding blend, suggesting that such materials may be interesting for enhanced thermal stability of organic photovoltaic active layers based on similar systems.
关键词： fluorination,conjugated block-copolymer synthesis,microphase stabilization,polythiophene,temperature-dependent Raman spectroscopy
更新于2025-09-19 17:15:36
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Electroactive materials with tunable response based on block copolymer self-assembly
摘要： Ferroelectric polymers represent one of the key building blocks for the preparation of flexible electronic devices. However, their lack of functionality and ability to simply tune their ferroelectric response significantly diminishes the number of fields in which they can be applied. Here we report an effective way to introduce functionality in the structure of ferroelectric polymers while preserving ferroelectricity and to further tune the ferroelectric response by incorporating functional insulating polymer chains at the chain ends of ferroelectric polymer in the form of block copolymers. The block copolymer self-assembly into lamellar nanodomains allows confined crystallization of the ferroelectric polymer without hindering the crystallinity or chain conformation. The simple adjustment of block polarity leads to a significantly different switching behavior, from ferroelectric to antiferroelectric-like and linear dielectric. Given the simplicity and wide flexibility in designing molecular structure of incorporated blocks, this approach shows the vast potential for application in numerous fields.
关键词： Block copolymer self-assembly,Tunable response,Ferroelectric polymers,Electroactive materials
更新于2025-09-19 17:15:36
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Confined versus Unconfined Crystallization in Block Copolymer/Salt Mixtures Studied by Depolarized Light Scattering
摘要： Crystallization in an ordered lamellar diblock copolymer/salt mixture, polystyrene-block-poly(ethylene oxide) mixed with lithium bis(trifluoromethanesulfonyl)imide salt (SEO/LiTFSI), has been studied using a combination of small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), and depolarized light scattering (DPLS). Such materials have applications as electrolyte membranes in solid-state lithium batteries. The grain structure of the electrolyte was controlled by manipulating thermal history. Poly(ethylene oxide) (PEO) crystallization was confined within the microphase-separated morphology and did not affect the grain structure in the case of shallow quenches. Deep quenches resulted in unconfined crystallization, where crystal formation does not affect the microphase-separated morphology but does alter the grain structure. The difference between the two modes of crystallization can only be detected by DPLS. This knowledge is particularly relevant for nanostructured electrolytes wherein ion transport is a strong function of grain structure.
关键词： grain structure,block copolymer,crystallization,electrolyte,depolarized light scattering
更新于2025-09-19 17:15:36
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Self-assembled bulk heterojunctions from integral molecules with nonconjugately linked donor and acceptor units for photovoltaic applications
摘要： The bi-continuous interpenetrating network of donor/acceptor with suitable phase-separated domain size is crucial for highly efficient organic bulk heterojunction solar cells considering that it guarantees effective exciton dissociation and smooth charge transport. For traditional binary blend bulk heterojunction, the photoactive layer is a simple physical mixture of donor and acceptor, the size of phase separation is primarily determined by the aggregation characteristics of the donor and acceptor respectively, it is hard to control and stabilize. To solve this problem, a kind of donor-acceptor integral molecule with donor units and acceptor units linked by non-conjugated flexible linking units has been proposed. The energy levels and the absorption spectra of the integral molecules can be easily tailed by tuning the donor and the acceptor units. Furthermore, the integral molecules can form a microphase separated bulk heterojunction of donor phase and acceptor phase through a self-assembly process of the molecule, which is governed by the flexible linking unit, responsible for connecting the donor and acceptor units. Since the donor and acceptor units of the integral molecules are connected by the non-conjugated units, the scale of aggregation and the morphology stability could be easily controlled. In this review, we first introduce the unique characteristics of the three typical donor-acceptor integral molecules and then highlight their current developments. For each donor-acceptor molecule, we attempt to give a detailed summarization on their design and synthesis, and an in-depth understanding on the basic mechanism of molecular self-assembly and the performance comparison of SMSCs. In the end, the prospect and potential improvements of donor-acceptor integral molecule are addressed, and we believe that emerging donor-acceptor molecule provide great opportunities for efficient and stable organic solar cells.
关键词： double-cable polymer,self-assembly,donor-acceptor integral molecule,donor-acceptor small molecule,single material organic solar cell,block copolymer
更新于2025-09-19 17:13:59
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Morphological Study of Blend Thin Films of Poly(3-hexylthiophene)-<i>block</i>-polyisobutylene-<i>block</i>-poly(3-hexylthiophene):Poly(3-hexylthiophene) and Their Application to Photovoltaics
摘要： The detailed morphological studies of poly(3-hexylthiophene)(P3HT)-b-polyisobutylene(PIB)-b-P3HT:P3HT blend thin films by grazing incidence X-ray scattering (GIXS) were reported. The results of GIXS experiments indicated the formation of phase separation between P3HT and PIB domains even after blending the P3HT homopolymer below 30 wt%. The change in d-spacing values of the phase-separated under strains was suppressed by increasing the weight ratio of the P3HT homopolymer, probably due to the disruption of the microphase separation. The blending the P3HT homopolymer induced the edge-on orientation during the strain process below 75%, probably by improving the interaction between P3HT domains in the blend thin films. The OPV characteristics were obtained with the device structure of ITO/PEDOT:PSS/P3HT-b-PIB-b-P3HT:P3HT:PC61BM/Ca/Al, significantly improving the JSC and FF values by increasing the P3HT homopolymer weight ratio. The excellent elongation behavior of P3HT-b-PIB-b-P3HT:P3HT blend bulk films (P3HT < 30 wt%) could be achieved, probably due to the formation of microphase separation between semi-crystalline P3HT and rubbery PIB domains.
关键词： Organic photovoltaic,Morphology,Block copolymer,π-Conjugated polymer,Elastomer,Synchrotron X-ray scattering
更新于2025-09-16 10:30:52
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Polymeric Ionic Liquid-Based Fluorescent Amphiphilic Block Copolymer Micelle for Selective and Sensitive Detection of p-Phenylenediamine
摘要： Highly sensitive and selective detection of p-phenylenediamine (PPD) is achieved by a fluorescence sensor, which is constructed by encapsulating the hydrophobic fluorescent 1-pyrenecarboxaldehyde (Py-CHO) into the polymeric ionic liquid (PIL)-based amphiphilic block copolymers (BCPs) micelle. Amine-aldehyde condensation reaction between PPD and Py-CHO leads to the fluorescence quenching of Py-CHO, giving rise to the basis for quantitative detection of PPD. The core cavity of micelle formed by the self-assembly of PIL provides excellent hydrophobic environment for the accommodation of fluorescent Py-CHO, offering the significant improved sensitivity and selectivity on PPD detection. The amount of PIL in fabricating amphiphilic block copolymer micelle, the BCPs-Py-CHO micelle concentration and the detection pH condition are investigated to obtain the best performance of this sensor. Accurate detection of PPD is achieved in the range of 0.02-10 μmol L-1 under optimal conditions, and the detection limit is 0.007 μmol L-1 (3σ/s). The developed sensor is successfully applied to the determination of PPD contents in hair dyes, spiked water and urine samples.
关键词： Amphiphilic block copolymer micelle,p-Phenylenediamine,Fluorescence sensor,Polymeric ionic liquid,1-Pyrenecarboxaldehydes
更新于2025-09-10 09:29:36
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Amplified Split Aptamer Sensor Delivered Using Block Copolymer Nanoparticles for Small Molecule Imaging in Living Cells
摘要： We develop a novel amplified split aptamer sensor for highly sensitive detection and imaging of small molecules in living cells by using cationic block copolymer nanoparticles (BCNs) with entrapped fluorescent conjugated polymer as a delivery agent. The design of split aptamer as the initiator of hybridization chain reaction (HCR) affords the possibility of enhancing the signal-to-background ratio and thus allows high-contrast imaging for small molecules with relatively weak interactions with their aptamers. The novel design of using fluorescent cationic BCNs as the nanocarrier enables efficient and self-tracking transfection of DNA probes. Results reveal that BCNs exhibit high fluorescence brightness allowing direct tracking of the delivery location. The developed amplified split aptamer sensor is shown to have high sensitivity and selectivity for in vitro quantitative detection of ATP with a detection limit of 30 nM. Live cell studies show that the sensor provides a "signal on" approach for specific, high-contrast imaging of ATP. The DNA sensor based HCR system may provide a new generally applicable platform for detection and imaging of low-abundance biomarkers.
关键词： sensor,small molecule imaging,enzyme-free amplification,block copolymer nanoparticles,split aptamer
更新于2025-09-10 09:29:36
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Orientation and Morphology Control of Liquid Crystalline Block Copolymer Thin Film by Liquid Crystalline Solvent
摘要： The critical challenge to engineer the morphological structures in the strongly phase segregated block copolymer thin film is to overcome the preferential wetting of the blocks at interface and direct the self-assembly process. Herein, we utilize surface activity and selective solvation of a nematic (N) liquid crystalline (LC) solvent, 5CB, to facilely alter the LC anchoring and the orientation of the nano-phase separated structures of the smectic-nematic (S-N) LC block copolymer thin film. For the neat S-N diblock copolymer thin film, the nano-structures are parallel aligned. In contrast, with continuous introduction of 5CB into the system, the orientations of the characteristic nano-structures and the morphologies of the LC thin film can be consequently changed, yielding the perpendicularly oriented lamellar or cylindrical structures with the feature size below 10 nm. The homeotropic alignment of the 5CB nematics near the air interface plays a critical role to induce this unique behavior in the S-N/5CB systems, which offers an opportunity to fine-tune the interfacial structures and the morphological patterning in the block copolymer thin film.
关键词： Thin film,Self-assembly,5CB,Liquid crystalline block copolymer,Nano-structures
更新于2025-09-10 09:29:36