Showing papers on "Polymer published in 2022"

A New Polymer Donor Enables Binary All‐Polymer Organic Photovoltaic Cells with 18% Efficiency and Excellent Mechanical Robustness

Abstract: The development of polymerized small‐molecule acceptors has boosted the power conversion efficiencies (PCEs) of all‐polymer organic photovoltaic (OPV) cells to 17%. However, the polymer donors suitable for all‐polymer OPV cells are still lacking, restricting the further improvement of their PCEs. Herein, a new polymer donor named PQM‐Cl is designed and its photovoltaic performance is explored. The negative electrostatic potential and low average local ionization energy distribution of the PQM‐Cl surface enable efficient charge generation and transfer process. When blending with a well‐used polymer acceptor, PY‐IT, the PQM‐Cl‐based devices deliver an impressive PCE of 18.0% with a superior fill factor of 80.7%, both of which are the highest values for all‐polymer OPV cells. The relevant measurements demonstrate that PQM‐Cl‐based films possess excellent mechanical and flexible properties. As such, PQM‐Cl‐based flexible photovoltaic cells are fabricated and an excellent PCE of 16.5% with high mechanical stability is displayed. These results demonstrate that PQM‐Cl is a potential candidate for all‐polymer OPV cells and provide insights into the design of polymer donors for high‐efficient all‐polymer OPV cells.

Completely aqueous processable stimulus responsive organic room temperature phosphorescence materials with tunable afterglow color

Abstract: Abstract Many luminescent stimuli responsive materials are based on fluorescence emission, while stimuli-responsive room temperature phosphorescent materials are less explored. Here, we show a kind of stimulus-responsive room temperature phosphorescence materials by the covalent linkage of phosphorescent chromophore of arylboronic acid and polymer matrix of poly(vinylalcohol). Attributed to the rigid environment offered from hydrogen bond and B-O covalent bond between arylboronic acid and poly(vinylalcohol), the yielded polymer film exhibits ultralong room temperature phosphorescence with lifetime of 2.43 s and phosphorescence quantum yield of 7.51%. Interestingly, the RTP property of this film is sensitive to the water and heat stimuli, because water could destroy the hydrogen bonds between adjacent poly(vinylalcohol) polymers, then changing the rigidity of this system. Furthermore, by introducing another two fluorescent dyes to this system, the color of afterglow with stimulus response effect could be adjusted from blue to green to orange through triplet-to-singlet Förster-resonance energy-transfer. Finally, due to the water/heat-sensitive, multicolor and completely aqueous processable feature for these three afterglow hybrids, they are successfully applied in multifunctional ink for anti-counterfeit, screen printing and fingerprint record.

Advances in porous organic polymers: syntheses, structures, and diverse applications

Abstract: In this review, we discuss the progress in the preparation methods and diverse applications for covalent triazine frameworks, hypercrosslinked polymers, covalent organic frameworks, and conjugated microporous polymers.

Rational design of mixed-matrix metal-organic framework membranes for molecular separations

Abstract: Conventional separation technologies to separate valuable commodities are energy intensive, consuming 15% of the worldwide energy. Mixed-matrix membranes, combining processable polymers and selective adsorbents, offer the potential to deploy adsorbent distinct separation properties into processable matrix. We report the rational design and construction of a highly efficient, mixed-matrix metal-organic framework membrane based on three interlocked criteria: (i) a fluorinated metal-organic framework, AlFFIVE-1-Ni, as a molecular sieve adsorbent that selectively enhances hydrogen sulfide and carbon dioxide diffusion while excluding methane; (ii) tailoring crystal morphology into nanosheets with maximally exposed (001) facets; and (iii) in-plane alignment of (001) nanosheets in polymer matrix and attainment of [001]-oriented membrane. The membrane demonstrated exceptionally high hydrogen sulfide and carbon dioxide separation from natural gas under practical working conditions. This approach offers great potential to translate other key adsorbents into processable matrix. Description Mixed-matrix membranes using nanosheets Selective adsorbents can show enhanced separation of components from mixed-gas streams, but these materials can often be difficult to fabricate into large-scale, robust membranes. Datta et al. report the synthesis and characterization of a mixed-matrix membrane. They first describe the synthesis of sheets of the metal organic framework (MOF) material AlFFIVE-1-Ni. By using nanosheets instead of the more commonly synthesized MOF nanoparticles, the authors were able to achieve much better alignment, loading fractions up to 60%, and better polymer-MOF compatibility when embedding the MOF nanosheets into a polymer matrix. These mixed-matrix membranes exhibited improved carbon dioxide and methane selectivity relative to many other comparable ones, as well as the ability to remove hydrogen sulfide. —MSL High loading of metal organic framework materials enables efficient upgrading of natural gas by removing carbon dioxide and hydrogen sulfide.

A Vinylene‐Linker‐Based Polymer Acceptor Featuring a Coplanar and Rigid Molecular Conformation Enables High‐Performance All‐Polymer Solar Cells with Over 17% Efficiency

Abstract: State‐of‐art Y‐series polymer acceptors are typically based on a mono‐thiophene linker, which can cause some twisted molecular conformations and thus limit the performance of all‐polymer solar cells (all‐PSCs). Here, a high‐performance polymer acceptor based on vinylene linkers is reported, which leads to surprising changes in the polymers’ molecular conformations, optoelectronic properties, and enhanced photovoltaic performance. It is found that the polymer acceptors based on thiophene or bithiophene linkers (PY‐T‐γ and PY‐2T‐γ) display significant molecular twisting between end‐groups and linker units, while the vinylene‐based polymer (PY‐V‐γ) exhibits a more coplanar and rigid molecular conformation. As a result, PY‐V‐γ demonstrates a better conjugation and tighter interchain stacking, which results in higher mobility and a reduced energetic disorder. Furthermore, detailed morphology investigations reveal that the PY‐V‐γ‐based blend exhibits high domain purity and thus a better fill factor in its all‐PSCs. With these, a higher efficiency of 17.1% is achieved in PY‐V‐γ‐based all‐PSCs, which is the highest efficiency reported for binary all‐PSCs to date. This work demonstrates that the vinylene‐linker is a superior unit to build polymer acceptors with more coplanar and rigid chain conformation, which is beneficial for polymer aggregation and efficient all‐PSCs.

Stimulus-responsive room temperature phosphorescence materials with full-color tunability from pure organic amorphous polymers

Abstract: Achieving stimulus-responsive ultralong room temperature phosphorescence (RTP) in organic materials especially with full-color tunable emissions is attractive and important but rarely reported. Here, a strategy was reported to realize stimulus-responsive RTP effect with color-tunable emissions by using water as solvent in the preparation process without any organic solvent through covalent linkage of arylboronic acids with different π conjugations and polymer matrix of polyvinyl alcohol. The yielded polymer films exhibit outstanding RTP performance (2.43 s). Furthermore, an excitation-dependent RTP film was obtained, and the afterglow color changes from blue to green, then to red as the excitation wavelength increases. The RTP property of all the above materials is sensitive to water and heat stimuli, because the rigidity of the system could be broken by water. Last, they were successfully applied in a multilevel information encryption and multicolor paper and ink.

Completely aqueous processable stimulus responsive organic room temperature phosphorescence materials with tunable afterglow color

Abstract: Abstract Many luminescent stimuli responsive materials are based on fluorescence emission, while stimuli-responsive room temperature phosphorescent materials are less explored. Here, we show a kind of stimulus-responsive room temperature phosphorescence materials by the covalent linkage of phosphorescent chromophore of arylboronic acid and polymer matrix of poly(vinylalcohol). Attributed to the rigid environment offered from hydrogen bond and B-O covalent bond between arylboronic acid and poly(vinylalcohol), the yielded polymer film exhibits ultralong room temperature phosphorescence with lifetime of 2.43 s and phosphorescence quantum yield of 7.51%. Interestingly, the RTP property of this film is sensitive to the water and heat stimuli, because water could destroy the hydrogen bonds between adjacent poly(vinylalcohol) polymers, then changing the rigidity of this system. Furthermore, by introducing another two fluorescent dyes to this system, the color of afterglow with stimulus response effect could be adjusted from blue to green to orange through triplet-to-singlet Förster-resonance energy-transfer. Finally, due to the water/heat-sensitive, multicolor and completely aqueous processable feature for these three afterglow hybrids, they are successfully applied in multifunctional ink for anti-counterfeit, screen printing and fingerprint record.

Selective photocatalytic CO2 reduction in aerobic environment by microporous Pd-porphyrin-based polymers coated hollow TiO2

Abstract: Direct photocatalytic CO2 reduction from primary sources, such as flue gas and air, into fuels, is highly desired, but the thermodynamically favored O2 reduction almost completely impedes this process. Herein, we report on the efficacy of a composite photocatalyst prepared by hyper-crosslinking porphyrin-based polymers on hollow TiO2 surface and subsequent coordinating with Pd(II). Such composite exhibits high resistance against O2 inhibition, leading to 12% conversion yield of CO2 from air after 2-h UV-visible light irradiation. In contrast, the CO2 reduction over Pd/TiO2 without the polymer is severely inhibited by the presence of O2 ( ≥ 0.2 %). This study presents a feasible strategy, building Pd(II) sites into CO2-adsorptive polymers on hollow TiO2 surface, for realizing CO2 reduction with H2O in an aerobic environment by the high CO2/O2 adsorption selectivity of polymers and efficient charge separation for CO2 reduction and H2O oxidation on Pd(II) sites and hollow TiO2, respectively.

Highly Conducting and Stretchable Double‐Network Hydrogel for Soft Bioelectronics

Abstract: Conducting polymer hydrogels are promising materials in soft bioelectronics because of their tissue‐like mechanical properties and the capability of electrical interaction with tissues. However, it is challenging to balance electrical conductivity and mechanical stretchability: pure conducting polymer hydrogels are highly conductive, but they are brittle; while incorporating the conducting network with a soft network to form a double network can improve the stretchability, its electrical conductivity significantly decreases. Here, the problem is addressed by concentrating a poorly crosslinked precursor hydrogel with a high content ratio of the conducting polymer to achieve a densified double‐network hydrogel (5.5 wt% conducting polymer), exhibiting both high electrical conductivity (≈10 S cm–1) and a large fracture strain (≈150%), in addition to high biocompatibility, tissue‐like softness, low swelling ratio, and desired electrochemical properties for bioelectronics. A surface grafting method is further used to form an adhesive layer on the conducting hydrogel, enabling robust and rapid bonding on the tissues. Furthermore, the proposed hydrogel is applied to show high‐quality physiological signal recording and reliable, low‐voltage electrical stimulation based on an in vivo rat model. This method provides an ideal strategy for rapid and reliable tissue‐device integration with high‐quality electrical communications.

Understanding, quantifying, and controlling the molecular ordering of semiconducting polymers: from novices to experts and amorphous to perfect crystals

Abstract: Molecular packing and texture of semiconducting polymers are often critical to the performance of devices using these materials. Although frameworks exist to quantify the ordering, interpretations are often just qualitative, resulting in imprecise use of terminology. Here, we reemphasize the significance of quantifying molecular ordering in terms of degree of crystallinity (volume fractions that are ordered) and quality of ordering and their relation to the size scale of an ordered region. We are motivated in part by our own imprecise and inconsistent use of terminology in the past, as well as the need to have a primer or tutorial reference to teach new group members. We strive to develop and use consistent terminology with regards to crystallinity, semicrystallinity, paracrystallinity, and related characteristics. To account for vastly different quality of ordering along different directions, we classify paracrystals into 2D and 3D paracrystals and use paracrystallite to describe the spatial extent of molecular ordering in 1-10 nm. We show that a deeper understanding of molecular ordering can be achieved by combining grazing-incidence wide-angle X-ray scattering and differential scanning calorimetry, even though not all aspects of these measurements are consistent, and some classification appears to be method dependent. We classify a broad range of representative polymers under common processing conditions into five categories based on the quantitative analysis of the paracrystalline disorder parameter (g) and thermal transitions. A small database is presented for 13 representative conjugated and insulating polymers ranging from amorphous to semi-paracrystalline. Finally, we outline the challenges to rationally design more perfect polymer crystals and propose a new molecular design approach that envisions conceptual molecular grafting that is akin to strained and unstrained hetero-epitaxy in classic (compound) semiconductors thin film growth.

Recent advances of interphases in carbon fiber-reinforced polymer composites: A review

Abstract: Carbon fiber reinforced polymer (CFRP) have excellent properties such as light weight, high strength, high modulus and high temperature resistance, and have wide application prospect in the fields of national defense, aerospace and high-end civilian products. Various methods have been exploited to modify the CF to increase the surface activity, roughness and wettability , so that the interfacial adhesion between fiber and matrix could be improved for better mechanical properties, which is helpful to meet the needs of more fields for high-performance CFRP. In this review, the recent progress of CF surface modification methods and their reinforcing effects on composites are mainly summarized. Finally, some issues of CFRP are discussed and the future trends of interfacial reinforcement research are prospected.

Molecular Design of Stretchable Polymer Semiconductors: Current Progress and Future Directions.

Abstract: Stretchable polymer semiconductors have advanced rapidly in the past decade as materials required to realize conformable and soft skin-like electronics become available. Through rational molecular-level design, stretchable polymer semiconductor films are now able to retain their electrical functionalities even when subjected to repeated mechanical deformations. Furthermore, their charge-carrier mobilities are on par with the best flexible polymer semiconductors, with some even exceeding that of amorphous silicon. The key advancements are molecular-design concepts that allow multiple strain energy-dissipation mechanisms, while maintaining efficient charge-transport pathways over multiple length scales. In this perspective article, we review recent approaches to confer stretchability to polymer semiconductors while maintaining high charge carrier mobilities, with emphasis on the control of both polymer-chain dynamics and thin-film morphology. Additionally, we present molecular design considerations toward intrinsically elastic semiconductors that are needed for reliable device operation under reversible and repeated deformation. A general approach involving inducing polymer semiconductor nanoconfinement allows for incorporation of several other desired functionalities, such as biodegradability, self-healing, and photopatternability, while enhancing the charge transport. Lastly, we point out future directions, including advancing the fundamental understanding of morphology evolution and its correlation with the change of charge transport under strain, and needs for strain-resilient polymer semiconductors with high mobility retention.

The mechanochemical synthesis of polymers

Abstract: Mechanochemistry – the utilization of mechanical forces to induce chemical reactions – is a rarely considered tool for polymer synthesis. It offers numerous advantages such as reduced solvent consumption, accessibility of novel structures, and the avoidance of problems posed by low monomer solubility and fast precipitation. Consequently, the development of new high-performance materials based on mechanochemically synthesised polymers has drawn much interest, particularly from the perspective of green chemistry. This review covers the constructive mechanochemical synthesis of polymers, starting from early examples and progressing to the current state of the art while emphasising linear and porous polymers as well as post-polymerisation modifications.

Polymerized Small Molecular Acceptor with Branched Side Chains for All Polymer Solar Cells with Efficiency over 16.7%

Abstract: The power conversion efficiencies (PCEs) of small molecule acceptor (SMA)‐based organic solar cells have already exceeded 18%. However, the development of polymer acceptors still lags far behind their SMA counterparts mainly due to the lack of efficient polymer acceptors. Herein, a series of polymer acceptors named PY‐X (with X being the branched alkyl chain) are designed and synthesized by employing the same central core with the SMA L8‐BO but with different branched alkyl chains on the pyrrole motif. It is found that the molecular packing of SMA‐HD featuring 2‐hexyldecyl side chain used in the synthesis of PY‐HD is similar to L8‐BO, in which the branched alkyl chains lead to condensed and high‐order molecular assembly in SMA‐HD molecules. When combined with PM6, PY‐HD‐based all polymer solar cell (all‐PSC) exhibits a high PCE of 16.41%, representing the highest efficiency for the binary all‐PSCs. Moreover, the side‐chain modification on the pyrrole site position further improves the performance of the all‐PSCs, and the PY‐DT‐based device delivers a new record high efficiency of 16.76% (certified as 16.3%). The work provides new insights for understanding the structure–property relationship of polymer acceptors and paves a feasible avenue to develop efficient conjugated polymer acceptors.

Hydro/Organo/Ionogels: “Controllable” Electromagnetic Wave Absorbers

Abstract: Demand for electromagnetic wave (EMW) absorbers continues to increase with technological advances in wearable electronics and military applications. In this study, a new strategy to overcome the drawbacks of current absorbers by employing the co‐contribution of functional polymer frameworks and liquids with strong EMW absorption properties is proposed. Strongly polar water, dimethyl sulfoxide/water mixtures, and highly conductive 1‐ethyl‐3‐methylimidazolium ethyl sulfate ([EMI][ES]) are immobilized in dielectrically inert polymer networks to form different classes of gels (hydrogels, organogels, and ionogels). These gels demonstrate a high correlation between their dielectric properties and polarity/ionic conductivity/non‐covalent interaction of immobilized liquids. Thus, the EMW absorption performances of the gels can be precisely tuned over a wide range due to the diversity and stability of the liquids. The prepared hydrogels show good shielding performance (shielding efficiency > 20 dB) due to the high dielectric constants, while organogels with moderate attenuation ability and impedance matching achieve full‐wave absorption in X‐band (8.2–12.4 GHz) at 2.5 ± 0.5 mm. The ionogels also offer a wide effective absorption bandwidth (10.79–16.38 GHz at 2.2 mm) via prominent ionic conduction loss. In short, this work provides a conceptually novel platform to develop high‐efficient, customizable, and low‐cost functional absorbers.