Direct Polymerization Research Articles

Solid Forms of Bio-Based Monomer Salts for Polyamide 512 and Their Effect on Polymer Properties.

Polyamides' properties are greatly influenced by the polymerization process and the type of feedstock used. The solid forms of nylon salts play a significant role in determining the final characteristics of the material. This study focuses on the long-chain bio-nylon 512. Firstly, we systematically investigated the possible solid forms of the nylon 512 salt, including crystal forms and morphologies, by massive experimental screening, single-crystal X-ray diffraction, Hirshfeld surface analysis, and TG-DSC measurements. The regulation and control of the various solid forms were achieved through solid-state transformations (SSTs) and solution-mediated phase transformations (SMPTs). Our findings shows that the nylon 512 salt exists in two crystal forms (anhydrate and dihydrate) and four morphologies (needle-like, plate-like, rod-like, and massive block crystal). Many factors will influence the formation of these solid forms, such as water activity, temperature, solvent, and ultrasonic physical fields. We can choose the right factors to regulate this as needed. On this basis, we studied the effects of different solid forms (crystal forms and morphologies) on the properties of the resulting polyamides prepared using direct solid-state polymerization (DSSP). The solid form of the salt had many effects on the polymer, including its structure, melting point, and mechanical properties. The polyamide obtained through DSSP of the anhydrate salt exhibited a higher melting point (204.22 °C) and greater elastic modulus (3.366 GPa) compared to that of the dihydrate salt, especially for the anhydrate salt of plate-like crystals.

Electrochromic conjugated polymers: The relationship of gradient band gap and electrochromic performance

In the pursuit of high-performance electrochromic materials, in this paper, six donor-acceptor type with different gradient band gaps electrochromic conjugated polymers, named PBTz-T, PBTz-TT, PBTz-DT, PTBTO8-T, PTBTO8-TT, and PTBTO8-DT, were synthesized via direct (hetero) arylation polymerization, employing two benzothiadiazole derivatives with varying electron-accepting capabilities and three thiophene derivatives with different electron-donating capacities. The structures, optical, electrochemical, and electrochromic properties of the six polymers were investigated. As the number of fused thiophene increases, enhancing the electron-donating ability, a growth trend of electrochemical stability is observed for all polymers. Meanwhile, enhance electron-accepting capabilities of acceptors (from benzotriazole to benzothiadiazole) significantly lower the electronic band gap and improve electrochemical stability. PBTz-DT boasts a bleaching time of 0.3 s, outperforming most reported electrochromic polymers. PBTz-T, at 530 nm, exhibits exceptionally high coloration efficiency, reaching 916 cm2 C⁻1, and demonstrates higher electron utilization and lower energy consumption, making it an excellent candidate for high-performance electrochromic devices. This work compared studies the relationship of gradient band gaps of electrochromic conjugated polymers and their electrochemical and electrochromic performance, offers new insights into enhancing the electrochemical stability and synthesizing high coloration efficiency electrochromic materials.

Sustainable Formate Production via Highly Active CO2 Hydrogenation Using Porous Organometallic Polymer with Ru-PNP Active Sites.

Efforts to combine the advantages of homogeneous catalysts in terms of activity with the ease of separation process offered by heterogeneous catalysts continue to be actively pursued in the field of catalyst development. Heterogeneous catalysts were synthesized from Ru-MACHO organometallic compounds, recognized for their high hydrogenation catalytic activity linked to the active site of the Ru-PNP motif, through direct polymerization utilizing the Friedel-Crafts reaction. These catalysts were then applied for the conversion of greenhouse gas carbon dioxide (CO2) into formate via hydrogenation, exhibited with a record-high turnover frequency of 31,700 and a productivity of 36,100 kgformate/(kgcatalyst·d). Furthermore, the facile separation characteristics and recyclability of the heterogeneous catalysts were confirmed.

Dimension-matching crystallized linear conjugated polymer/graphitic carbon nitride heterojunctions for boosting visible/near-infrared light photocatalytic hydrogen production

Linear conjugated polymer photocatalysts remain suffer from insufficient near-infrared light absorption and poor photogenerated-carriers separation efficiency caused by twisted backbone, limiting their further application for photocatalytic water splitting to produce hydrogen energy. Herein, we first synthesized crystallized 2D poly(thiophene-co-nitrothiophene) (PN) with narrow band gap through direct (hetero) arylation polymerization (DHAP) method, then constructed dimension-matching PN/graphitic carbon nitride (CN) heterojunctions (PN/CN) with 2D/2D structure for visible/near-infrared light photocatalytic hydrogen production. The resulting 2D/2D heterojunctions exhibit excellent visible/near-infrared light absorption and photocatalytic activates. The ratio-optimized 15PN/CN shows boosting hydrogen production activity up to 11.73 mmol/hg−1 under visible/near-infrared light (λ > 420 nm) irradiation, which is ∼ 30-time and ∼ 46.9-time improvement than that of PN and CN separately. Notably, the apparent quantum yield (AQY) of 15PN/CN is calculated to be 2.35 % at 700 nm and 0.62 % at 800 nm. It is proved that the π − π interaction of dimension-matching heterojunctions between PN and CN facilitates electrons transfer from LUMO of PN to LUMO of CN. This study provides another new train of thought for reasonably developing dimension-matching polymer heterojunctions by manipulating crystallinity and band structure of linear conjugated polymers for efficient visible/near-infrared light photocatalytic hydrogen production.

Construction of diverse adaptive camouflage nets based on soluble yellow-to-green switching electrochromic materials

The potential application of electrochromic (EC) materials and devices as adaptive camouflage in diverse environments requires further investigation. In this study, we aimed to enhance the camouflage effect of electrochromic devices (ECDs) by developing innovative EC camouflage nets. Three soluble EC materials (FTP, FEP and FBP) were synthesized by incorporating phenothiazine and ProDOT with different donors through direct(hetero) arylation polymerization. Due to the fine-tuning of the energy gap, the three materials exhibit yellow, yellowish-brown and reddish-brown colors in their neutral states, respectively. Particularly, FTP and FEP can switch between different yellow-to-green with superior EC performance. Furthermore, FTP-PEDOT and FEP-PEDOT ECDs were constructed. Notably, the FEP-PEDOT ECD demonstrated enhanced EC performance, characterized by a more noticeable yellow-to-green switch, faster switching times and improved cycle stability. To meet the adaptability for multi-environmental camouflage and wearable applications, we created diverse camouflage patterns using the mask-spray technique and developed three types (“stripe”/ “cross stripe”/ “block”) camouflage net ECDs. This study offers a comprehensive approach for developing adaptive camouflage nets tailored to diverse real combat settings.

Highly Transmissive, Processable, Highly Conducting and Stable Polythiophene Derivatives via Direct (Hetero)arylation Polymerization.

The development of modern optoelectronic devices increases the need for lightweight and flexible transparent conductors. It is thus essential to develop new eco-friendly materials that can be easily processed for the fabrication of such devices. For this purpose, the synthesis of self-doped, highly conducting, transmissive, and water-processable polythiophene derivatives was performed via the direct heteroarylation polymerization method and a protection/deprotection strategy. Stable conductivities up to 1000 S cm-1 have been obtained. Champion materials (P1 and P7) were scaled and processed via the roll-to-roll compatible slot-die coating method to demonstrate their large area applicability. The best coated films exhibited optical transmittance greater than 79% at 550 nm with sheet resistances of 116 Ω □-1. These values are comparable to indium-tin oxide on plastic and thus present a viable alternative to metal oxide-based electrodes.

Design and synthesis of donor-acceptor electrochromic polymers with remarkable near-infrared modulation

Developing electrochromic polymers (ECPs) for application in smart windows is highly desirable in the electrochromic field. However, most ECPs present weak solar irradiance regulation due to the inverse visible and NIR modulation. Herein, three donor-acceptor polymers containing 4,7-bis(4-hexylthiophen-2-yl)benzo[c][1,2,5]thiadiazole (HT-TZ) units are synthesized via direct arylation polymerization (DArP) method, and two copolymers with similar structure are prepared by electrochemical copolymerization for comparison. The copolymers synthesized by the DArP method present weak visible and high NIR modulation with an average visible (380 nm–780 nm) contrast below 15 % and NIR (750 nm–1400 nm) contrast above 60 %, inducing a high solar heat gain coefficient (SHGC) difference above 0.2 between the neutral and oxidized states, which is much higher than the reported high-performance ECPs. Additionally, these synthesized copolymers also present good electrochromic properties such as good stability and normal coloration efficiency, confirming their broad application potential in smart windows.

Rational Monomer Design for the Synthesis of Conjugated Polymers by Direct Heteroarylation Polymerization.

This study focuses on the design concepts that contribute to the C-H activation in bithiophene-flanked monomers incorporating naphthalene diimide (NDI), perylene diimide (PDI), and fluorene (FLU) and their polymerization by direct heteroarylation. Density functional theory (DFT) calculations reveal distinct energy requirements for C-H bond abstraction, which is dictated by the electron-withdrawing strength of the central aromatic core flanked by bithiophene. These provide insights into the reactivity of each monomer for C-H bond activation. Proton NMR spectroscopic experimental results confirm the favorable energetic profiles predicted by DFT, with NDI- and PDI-flanked monomers exhibiting lower energy requirements than fluorene-flanked monomers. Successful polymer synthesis is demonstrated for NDI and PDI, while the fluorene-flanked monomer shows challenges due to its higher energy demands.

Understanding Degradation Dynamics of Azomethine-containing Conjugated Polymers.

Understanding the influence of chemical environments on the degradation properties of conjugated polymers is an important task for the continued development of sustainable materials with potential utility in biomedical and optoelectronic applications. Azomethine-containing polymers were synthesized via palladium-catalyzed direct arylation polymerization (DArP) and used to study fundamental degradation trends upon exposure to acid. Shifts in the UV-vis absorbance spectra and the appearance/disappearance of aldehyde and imine diagnostic peaks within the 1H NMR spectra indicate that the polymers will degrade in the presence of acid. After degradation, the aldehyde starting material was recovered in high yields and was shown to maintain structural integrity when compared with commercial starting materials. Solution-degradation studies found that rates of degradation vary from 5 h to 90 s depending on the choice of solvent or acid used for hydrolysis. Additionally, the polymer was shown to degrade in the presence of perfluoroalkyl substances (PFASs), which makes them potentially useful as PFAS-sensitive sensors. Ultimately, this research provides strategies to control the degradation kinetics of azomethine-containing polymers through the manipulation of environmental factors and guides the continued development of azomethine-based materials.

Tailoring polyamide membranes via dynamic interfacial manipulation with functional Fe3O4 nanoparticles for elevated Nanofiltration performance

This study investigates the enhancement of thin-film-composite polyamide (TFC-PA) membranes for nanofiltration (NF) by conducting direct interfacial polymerization (IP) at a substrate-free water/n-hexane interface. Fe3O4 nanoparticles, stabilized with surfactants sodium laurate (SL) and hexadecyltrimethylammonium bromide (CTAB), were employed to dynamically influence the diffusion of piperazine (PIP) monomers. The incorporation of these nanoparticles enabled the modulation of the IP process, yielding membranes with distinct morphologies and performance characteristics. Specifically, membranes with SL-stabilized Fe3O4 (SLF) demonstrated enhanced cross-linking and superior salt rejection capabilities for divalent cations, with MgCl2 and CaCl2 rejection rates notably increasing to 95.5 % and 93.4 % respectively. Conversely, CTAB-stabilized Fe3O4 (CTABF) membranes, characterized by smoother surfaces and a looser structure, exhibited increases in water permeance up to 140 % relative to controls, but with a significant reduction in salt rejection efficacy as nanoparticle concentration increased. This study highlights the crucial impact of surfactant-stabilized nanoparticle modifications in manipulating the IP process and tailoring the filtration properties of PA membranes, offering promising avenues for optimizing NF membrane technology.

ILX-002 A Direct HbS Polymerization Inhibitor for the Treatment of Sickle Cell Disease

ILX-002 A Direct HbS Polymerization Inhibitor for the Treatment of Sickle Cell Disease

Synthesis, Characterization, and Investigation of Doxorubicin Drug Release Properties of Poly(acrylamide-co-acrylic Acid/Maleic Acid)-Hydroxyapatite Composite Hydrogel.

Hydroxyapatite and its derivatives have been used for a lot of applications. One of them is drug release studies. Due to its low adhesion strength and lack of the strength and durability required for load-carrying applications, there is a need to improve the properties of hydroxyapatite. For this aim, the most important factors are increasing pH sensitivity and preventing coagulation. Mixing it with multifunctional polymers is the best solution. The main objectives are: 1- preparing poly(acrylamide-co-acrylic acid/maleic acid)- hydroxyapatite (PAm-co-PAA/PMA-HApt), 2- assessment of (PAm-co-PAA/PMA-HApt) and dox-loaded poly(acrylamide-co-acrylic acid/maleic acid) (Dox-(PAm-co-PAA/PMA-HApt)) composite hydrogels, and 3- elucidating the difference in behavior of drug release studies between hydroxyapatite (HApt) and poly(acrylamide-co-acrylic acid/maleic acid) composite hydrogels. A composite of PAm-co-PAA/PMA-HApt was prepared by direct polymerization of acrylamide-co-acrylic acid/maleic acid in a suspension of HApt. The drug loading and release features of PAm-co-PAA/PMA-HApt and HApt were then investigated for doxorubicin (dox) release. Using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TG/DTA), this unique composite hydrogel has been physicochemically investigated. Also, a colorimetric assay was used to assess the in vitro biocompatible support and anticancer activity of HApt and the newly developed composite hydrogel XTT (2,3-Bis-(2-Methoxy-4-Nitro-5-Sulfophenyl)-2H-Tetrazolium-5-Carboxanilide) assay. According to the results of drug release studies of this new material, it is pH sensitive, and PAm-co-PAA/PMA-HApt demonstrated a faster release than HApt at 37°C in the acidic solution of pH 4.5 than in the neutral solution of pH 7.4. The XTT assay outcomes also demonstrated the biocompatibility of PAm-co-PAA/PMA-HApt and HApt and the cytotoxic effect of dox-loaded PAm-co-PAA/PMA-HApt. It should be inferred that the drug release profile was improved at pH 4.5 by the newly produced pH-sensitive composite hydrogel.

A Highly Conductive n-Type Conjugated Polymer Synthesized in Water.

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is a benchmark hole-transporting (p-type) polymer that finds applications in diverse electronic devices. Most of its success is due to its facile synthesis in water, exceptional processability from aqueous solutions, and outstanding electrical performance in ambient. Applications in fields like (opto-)electronics, bioelectronics, and energy harvesting/storage devices often necessitate the complementary use of both p-type and n-type (electron-transporting) materials. However, the availability of n-type materials amenable to water-based polymerization and processing remains limited. Herein, we present a novel synthesis method enabling direct polymerization in water, yielding a highly conductive, water-processable n-type conjugated polymer, namely, poly[(2,2'-(2,5-dihydroxy-1,4-phenylene)diacetic acid)-stat-3,7-dihydrobenzo[1,2-b:4,5-b']difuran-2,6-dione] (PDADF), with remarkable electrical conductivity as high as 66 S cm-1, ranking among the highest for n-type polymers processed using green solvents. The new n-type polymer PDADF also exhibits outstanding stability, maintaining 90% of its initial conductivity after 146 days of storage in air. Our synthetic approach, along with the novel polymer it yields, promises significant advancements for the sustainable development of organic electronic materials and devices.

Amplifying enantioselectivity in asymmetric transformations using heterogeneous chiral single-rhodium-site catalyst with sustained catalytic activity

Rhodium-catalyzed asymmetric reactions have played a pivotal role in the synthesis of functional chiral molecules. However, the ambiguous mechanism involving several plausible catalytically active species, the potential for catalyst deactivation and the need for constant reusability remain key challenges. Heterogeneous chiral Rh catalysts are highly desirable, but their performance has been hampered by low density and stability of catalytically active sites. Herein, we have devised a versatile methodology for fabricating highly efficient and robust chiral heterogeneous single-Rh-site catalysts by direct polymerization. The successful anchoring of single Rh-ligand species, the amplification of enantioselective inductive ability and the uniform distribution of atomic Rh sites within the resulting polymer matrix are identified as crucial factors contributing to their exceptional catalytic performance via comprehensive characterization and controlled experiments. In contrast to the corresponding homogeneous analogues, these chiral single-Rhodium-site catalysts exhibit outstanding performance, yielding enhanced enantioselectivity and broad applicability, even accommodating various functional groups. Remarkably, these results are achieved with just half catalyst dosage. Furthermore, their industrial potential is demonstrated through successful utilization in continuous flow processes and robust batch recycling. In future, we aim to expand the horizons of heterogeneous chiral single-metal-site catalysis, and bring us a step closer to practical asymmetric synthesis.

Green conversion of carbon disulfide to degradable polydithiourethanes through catalyst-free multicomponent polymerizations of diamines, carbon disulfide and diacrylates

In the pursuit of advanced functional polymer materials, sulfur-containing polymers have received tremendous attention owing to their superior chemical stability, high refractive indices, various supramolecular interactions, and robust dynamic covalent chemistry. However, their synthesis usually involves either expensive monomers or toxic byproducts and requires catalysts, thus hindering their widespread application. In this work, we present a catalyst-free multicomponent polymerization in organic solvents for the synthesis of various polydithiourethanes with excellent yields (up to 98 %) and high molecular weights (up to 112 kg/mol). This reaction involves the direct polymerization of carbon disulfide, an abundant one-carbon feedstock, with commercially available diamines and diacrylates. This polyaddition process demonstrates high atom economy and no byproduct, occurring at room temperature without the need for a catalyst, thus exhibiting excellent green chemistry metrics. By utilizing the dynamic covalent chemistry of dithiourethane groups, these polymers can be efficiently degraded via aminolysis and used to fabricate reprocessable vitrimers. This multicomponent polymerization opens up a new avenue for the efficient utilization of carbon disulfide resources and accelerates the exploration of diversified sulfur-containing functional polymer materials.

Conducting Polymers in Amperometric Sensors: A State of the Art over the Last 15 Years with a Focus on Polypyrrole-, Polythiophene-, and Poly(3,4-ethylenedioxythiophene)-Based Materials

Conducting polymers are used in a wide range of applications, especially in the design and development of electrochemical sensors. Their main advantage, in this context, is their ability to efficiently modify an electrode surface using the direct polymerization of a suitable monomer in an electrochemical cell, or by physical coating. Additionally, the conducting polymers can be mixed with further materials (metal nanoparticles, carbonaceous materials) to enhance conductivity and analytical features (linear range, limit of detection, sensitivity, and selectivity). Due to their characteristics, conducting polymer-based amperometric sensors are applied to the determination of different organic and inorganic analytes. A view of recent advances in this field focusing on pyrrole, thiophene, and 3,4-ethylenedioxythiophene as starting materials is reported.

Insights into interface engineering of g-C3N4/NaNbO3 heterojunction for photoelectrochemical water splitting

Green hydrogen is a very attractive energy source, a widely studied strategy among scientists to produce it is using metal oxide semiconductors as photoanodes for photoelectrochemical water splitting. The main challenge is to produce a photocatalyst that is stable and efficient enough to be commercially viable. In this sense, several different combinations of materials have been studied. Here, we report the preparation of g-C3N4/NaNbO3 coupled to Pt-based species (Pt-g-C3N4/NaNbO3) and its potential application as a photoanode for water photosplitting. NaNbO3 was chosen for its suitable properties, g-C3N4 was used to enhance the visible light activity, and Pt species were added to perform as a co-catalyst avoiding recombination of photogenerated charges. The main innovations are the reduced time and energy-consuming procedure to prepare NaNbO3 and the direct polymerization of the g-C3N4 on the NaNbO3. Results demonstrate the successful synthesis of the Pt-g-C3N4/NaNbO3 heterojunction; however, the resultant system showed low efficiency, probably for forming a layer of g-C3N4 on the top of NaNbO3 and electrically active surface states at the semiconductor/solution interfaces. Besides that, this study contributes valuable insights into the design of photoelectrodes for sustainable hydrogen production, especially due to the detailed research on the formation of the heterojunction.

Facile and scalable synthesis of functionalized hierarchical porous polymers for efficient uranium adsorption

Efficient uranium capture from wastewater holds great importance for the environmental remediation and sustainable development of nuclear energy, but it is a tremendous challenge. Herein, a facile and scalable approach is reported to fabricate functionalized hierarchical porous polymers (PPN-3) decorated with high density of phosphate groups for uranium adsorption. The as-constructed hierarchical porous structure could allow rapid diffusion of uranyl ions, while abundant phosphate groups that serve as adsorption sites could provide the high affinity for uranyl. Consequently, PPN-3 shows a high uranium adsorption uptake of 923.06 mg g−1 and reaches adsorption equilibrium within simply 10 min in uranium-spiked aqueous solution. Moreover, PPN-3 affords selective adsorption of uranyl over multiple metal ions and possesses a rapid and high removal rate of U(VI) in real water systems. Furthermore, this study offers direct polymerization strategy for the cost-effective fabrication of phosphate-functionalized porous organic polymers, which may provide promising application potential for uranium extraction.

Degradable π-Conjugated Polymers.

The integration of next-generation electronics into society is rapidly reshaping our daily interactions and lifestyles, revolutionizing communication and engagement with the world. Future electronics promise stimuli-responsive features and enhanced biocompatibility, such as skin-like health monitors and sensors embedded in food packaging, transforming healthcare and reducing food waste. Imparting degradability may reduce the adverse environmental impact of next-generation electronics and lead to opportunities for environmental and health monitoring. While advancements have been made in producing degradable materials for encapsulants, substrates, and dielectrics, the availability of degradable conducting and semiconducting materials remains restricted. π-Conjugated polymers are promising candidates for the development of degradable conductors or semiconductors due to the ability to tune their stimuli-responsiveness, biocompatibility, and mechanical durability. This perspective highlights three design considerations: the selection of π-conjugated monomers, synthetic coupling strategies, and degradation of π-conjugated polymers, for generating π-conjugated materials for degradable electronics. We describe the current challenges with monomeric design and present options to circumvent these issues by highlighting biobased π-conjugated compounds with known degradation pathways and stable monomers that allow for chemically recyclable polymers. Next, we present coupling strategies that are compatible for the synthesis of degradable π-conjugated polymers, including direct arylation polymerization and enzymatic polymerization. Lastly, we discuss various modes of depolymerization and characterization techniques to enhance our comprehension of potential degradation byproducts formed during polymer cleavage. Our perspective considers these three design parameters in parallel rather than independently while having a targeted application in mind to accelerate the discovery of next-generation high-performance π-conjugated polymers for degradable organic electronics.

Synthesis of 1,4‐dihydropyrrolo[3,2‐b]pyrrole‐containing donor–acceptor copolymers and their optoelectronic properties

AbstractDonor–acceptor (D–A)‐conjugated polymers have achieved promising performance metrics in numerous optoelectronic applications that continue to motivate studying structure–property relationships and discovering new materials. Here, the materials toolbox is expanded by synthesizing D–A copolymers where 1,4‐dihydropyrrolo[3,2‐b]pyrrole (DHPP) is directly incorporated into the main chain of D–A copolymers for the first time via direct heteroarylation polymerization. Notably, the synthetic complexity of DHPP‐containing polymers coupled with thieno[3,2‐b]pyrrole‐4,6‐dione (TPD) or 3,6‐bis(2‐thienyl)‐2,5‐dihydropyrrolo[3,4‐c]pyrrole‐1,4‐dione (Th2DPP) comonomers is calculated to be lower compared to many common conjugated polymers synthesized via direct arylation. The electron‐rich nature of DHPPs when coupled with TPD or DPP enables optoelectronic properties to be manipulated, evident by measuring distinctly different absorbance and redox properties. Additionally, these D–A copolymers demonstrate their potential in organic electronic applications, such as electrochromics and organic photovoltaics. The reported DHPP‐alt‐Th2DPP copolymer is the first DHPP‐based colored‐to‐transmissive electrochrome and achieves power conversion efficiencies of ~2.5% when incorporated into bulk heterojunction solar cells. Overall, the synthetic accessibility of DHPP monomers and their propensity to participate in robust polymerizations highlights the value of establishing structure–property relationships of an underutilized scaffold. These fundamental attributes serve to inform and advance efforts in the development of DHPP‐containing copolymers for various applications.