The Role of Lysozyme in the Formation of Bioinspired Silicon Dioxide.

Several organisms are able to polycondensate tetraoxosilicic(IV) acid to form silicon(IV) dioxide using polycationic molecules. According to an earlier mechanistic proposal, these molecules undergo a phase separation and recent experimental evidence appears to confirm this model. At the same time, polycationic proteins like lysozyme can also promote polycondensation of silicon(IV) dioxide, and they do so under conditions that are not compatible with liquid-liquid phase separation. In this manuscript we investigate this conundrum by molecular simulations.

Polyarylene-Based Anion Exchange Membranes for Fuel Cells.

Anion exchange membrane fuel cell (AEMFC) is an emerging and promising technology that can help realize a carbon-neutral, sustainable economy. Also, compared to the proton exchange membrane counterpart, AEMFC can achieve comparable cell outputs with lower costs due to the applicability of non-platinum group metal electrocatalysts for the reaction on the electrodes' surfaces. However, the wide application of the AEMFCs has been impeded by the unsatisfactory stability and performance of the hydroxide-conductive membranes in the past. Recently researchers have made breakthroughs using polyarylene (PA)-based AEMs. This article summarizes the recent advances of a class of AEMs with aromatic backbone without ether bonds, mainly synthesized by Friedel-Crafts polycondensation. Such PA-based AEMs showed high chemical/mechanical stabilities and ionic conductivity, and even the fuel cell with those AEMs showed impressive peak power density of up to 2.58 W cm-2. In this concept article, we classify major strategies for making PA-based AEMs to show the recent trends, highlight synthesis, characterization, and properties, and provide a brief outlook.

Nonstoichiometric Direct Arylation Polymerization of Octafluorobiphenyl with 2,7-Diiodofluorene for Regulating CH Terminals of π-Conjugated Polymer.

Nonstoichiometric direct arylation polycondensation of 2,2',3,3',5,5',6,6'-octafluorobiphenyl with excess of 2,7-diiodo-9,9-dioctyl-9H-fluorene is demonstrated. Pd/Ag dual-catalyst system under water/2-methyltetrahydrofuran biphasic conditions enables direct arylation under mild conditions and promotes the intramolecular transfer of a Pd catalyst walking through the fluorene moiety. The nonstoichiometric direct arylation polycondensation under the optimized reaction conditions produces the corresponding π-conjugated polymer with a high molecular weight and terminal octafluorobiphenyl units at both ends.

Unlocking the Potential of Polythioesters.

As the demand for sustainable polymers increases, most research efforts have focused on polyesters, which can be bioderived and biodegradable. Yet analogous polythioesters, where one of the oxygen atoms has been replaced by a sulfur atom, remain a relatively untapped source of potential. The incorporation of sulfur allows the polymer to exhibit a wide range of favorable properties, such as thermal resistance, degradability, and high refractive index. Polythioester synthesis represents a frontier in research, holding the promise of paving the way for eco-friendly alternatives to conventional polyesters. Moreover, polythioester research can also open avenues to the development of sustainable and recyclable materials. In the last 25 years, many methods to synthesize polythioesters have been developed. However, to date no industrial synthesis of polythioesters has been developed due to challenges of costs, yields, and the toxicity of the by-products. This review will summarize the recent advances in polythioester synthesis, covering step-growth polymerization, ring-opening polymerization (ROP), and biosynthesis. Crucially, the benefits and challenges of the processes will be highlighted, paying particular attention to their sustainability, with the aim of encouraging further exploration and research into the fast-growing field of polythioesters.

Thienoisoindigo-Based Conjugated Polymers Synthesized by Direct Arylation Polycondensation.

A series of thienoisoindigo (TIG)-based conjugated polymers (CPs) with high molecular weights are synthesized by direct arylation polycondensation (DArP) by using TIG derivatives as CBr monomer and multi-halogenated thiophene derivatives, i.e., (E)-1,2-bis(3,4-difluorothien-2-yl)ethene (4FTVT), (E)-1,2-bis(3,4-dichlorothien-2-yl)ethene (4ClTVT), 3,3',4,4'-tetrafluoro-2,2'-bithiophene (4FBT), and 3,3',4,4'-tetrachloro-2,2'-bithiophene (4ClBT), as CH monomers. Density functional theory (DFT) calculations reveal the high selectivity between α-CH bonds in 4FTVT, 4ClTVT, 4FBT, and 4ClBT and ß-CH bonds in TIG CBr monomer. All four resulting CPs exhibit low optical bandgaps of ca. 1.20 eV and ambipolar transport characteristics with both electron and hole mobility above 0.1 cm2  V-1  s-1 as elaborated with organic thin-film transistors (OTFTs). The polymer TIG-4FTVT delivers the best device performance. With this polymer, n-channel OTFTs with electron mobility up to 1.67 cm2  V-1  s-1 and p-channel OTFTs with hole mobility up to 0.62 cm2  V-1  s-1 are fabricated by modifying source/drain electrodes with polyethylenimine ethoxylated (PEIE) and MoO3 , respectively, to selectively inject electrons and holes.

Theoretical and Experimental Study of Different Side Chains on 3,4-Ethylenedioxythiophene and Diketopyrrolopyrrole-Derived Polymers: Towards Organic Transistors.

In this research, two polymers of P1 and P2 based on monomers consisting of thiophene, 3,4-Ethylenedioxythiophene (EDOT) and diketopyrrolopyrrole (DPP) are designed and obtained via Stille coupling polycondensation. The material shows excellent coplanarity and structural regularity due to the fine planarity of DPP itself and the weak non-covalent bonding interactions existing between the three units. Two different lengths of non-conjugated side chains are introduced and this has an effect on the intermolecular chain stacking, causing the film absorption to display different characteristic properties. On the other hand, the difference in the side chains does not have a significant effect on the thermal stability and the energy levels of the frontier orbitals of the materials, which is related to the fact that the materials both feature extremely high conjugation lengths and specific molecular compositions. Microscopic investigations targeting the side chains provide a contribution to the further design of organic semiconductor materials that meet device requirements. Tests based on organic transistors show a slight difference in conductivity between the two polymers, with P2 having better hole mobility than P1. This study highlights the importance of the impact of side chains on device performance, especially in the field of organic electronics.

Enzymatic Synthesis and Structural Modeling of Bio-Based Oligoesters as an Approach for the Fast Screening of Marine Biodegradation and Ecotoxicity.

Given the widespread use of esters and polyesters in products like cosmetics, fishing nets, lubricants and adhesives, whose specific application(s) may cause their dispersion in open environments, there is a critical need for stringent eco-design criteria based on biodegradability and ecotoxicity evidence. Our approach integrates experimental and computational methods based on short oligomers, offering a screening tool for the rapid identification of sustainable monomers and oligomers, with a special focus on bio-based alternates. We provide insights into the relationships between the chemical structure and properties of bio-based oligomers in terms of biodegradability in marine environments and toxicity in benchmark organisms. The experimental results reveal that the considered aromatic monomers (terephthalic acid and 2,5-furandicarboxylic acid) accumulate under the tested conditions (OECD 306), although some slight biodegradation is observable when the inoculum derives from sites affected by industrial and urban pollution, which suggests that ecosystems adapt to non-natural chemical pollutants. While clean seas are more susceptible to toxic chemical buildup, biotic catalytic activities offer promise for plastic pollution mitigation. Without prejudice to the fact that biodegradability inherently signifies a desirable trait in plastic products, nor that it automatically grants them a sustainable "license", this study is intended to facilitate the rational design of new polymers and materials on the basis of specific uses and applications.

A Microporous Poly(Arylene Ether) Platform for Membrane-Based Gas Separation.

Membrane-based gas separations are crucial for an energy-efficient future. However, it is difficult to develop membrane materials that are high-performing, scalable, and processable. Microporous organic polymers (MOPs) combine benefits for gas sieving and solution processability. Herein, we report membrane performance for a new family of microporous poly(arylene ether)s (PAEs) synthesized via Pd-catalyzed C-O coupling reactions. The scaffold of these microporous polymers consists of rigid three-dimensional triptycene and stereocontorted spirobifluorene, endowing these polymers with micropore dimensions attractive for gas separations. This robust PAE synthesis method allows for the facile incorporation of functionalities and branched linkers for control of permeation and mechanical properties. A solution-processable branched polymer was formed into a submicron film and characterized for permeance and selectivity, revealing lab data that rivals property sets of commercially available membranes already optimized for much thinner configurations. Moreover, the branching motif endows these materials with outstanding plasticization resistance, and their microporous structure and stability enables benefits from competitive sorption, increasing CO2 /CH4 and (H2 S+CO2 )/CH4 selectivity in mixture tests as predicted by the dual-mode sorption model. The structural tunability, stability, and ease-of-processing suggest that this new platform of microporous polymers provides generalizable design strategies to form MOPs at scale for demanding gas separations in industry.

Synthesis of sp2 Carbon-Conjugated Covalent Organic Framework Thin-Films via Copper-Surface-Mediated Knoevenagel Polycondensation.

sp2 carbon-conjugated covalent organic framework (sp2 c-COF) featured with high π-conjugation, high chemical stabilities, and designable chemical structures, are thus promising for applications including adsorption and separation, optoelectronic devices, and catalysis. For the most of these applications, large-area and continuous films are required. However, due to the needs of harsh conditions in the formation of CC bonds, classical interfacial methodologies are challenged in the synthesis of sp2 c-COFs films. Herein, a novel and robust interfacial method namely copper-surface-mediated Knoevenagel polycondensation (Cu-SMKP), is shown for scalable synthesis of sp2 c-COF films on various Cu substrates. Using this approach, large-area and continuous sp2 c-COF films could be prepared on various complicated Cu surfaces with thickness from tens to hundreds of nanometers. The resultant sp2 c-COF films on Cu substrate could be used directly as functional electrode for extraction of uranium from spiked seawater, which gives an exceptionally uptake capacity of 2475 mg g-1 . These results delineate significant synthetic advances in sp2 c-COF films and implemented them as functional electrodes for uranyl capture.

Intramolecular Palladium Catalyst Transfer on Benzoheterodiazoles as Acceptor Monomers and Discovery of Catalyst Transfer Inhibitors.

Intramolecular catalyst transfer on benzoheterodiazoles was investigated in Suzuki-Miyaura coupling reactions and polymerization reactions with t Bu3 PPd precatalyst. In the coupling reactions of dibromobenzotriazole, dibromobenzoxazole, and dibromobenzothiadiazole with pinacol phenylboronate, the product ratios of monosubstituted product to disubstituted product were 0/100, 27/73, and 89/11, respectively, indicating that the Pd catalyst undergoes intramolecular catalyst transfer on dibromobenzotriazole, whereas intermolecular transfer occurs in part in the case of dibromobenzoxazole and is predominant for dibromobenzothiadiazole. The polycondensation of 1.3 equivalents of dibromobenzotriazole with 1.0 equivalent of para- and meta-phenylenediboronates afforded high-molecular-weight polymer and cyclic polymer, respectively. In the case of dibromobenzoxazole, however, para- and meta-phenylenediboronates afforded moderate-molecular-weight polymer with bromine at both ends and cyclic polymer, respectively. In the case of dibromobenzothiadiazole, they afforded low-molecular-weight polymers with bromine at both ends. Addition of benzothiadiazole derivatives interfered with catalyst transfer in the coupling reactions.

Mechanism Study of the Polymerization of Polyamide 56: Reaction Kinetics and Process Parameters.

Polyamide 56 (PA56) has gained significant attention in the academic field due to its remarkable mechanical and thermal properties as a highly efficient and versatile biobased material. Its superior moisture absorption property also makes it a unique advantage in the realm of fiber textiles. However, despite extensive investigations on PA56's molecular and aggregate state structure, as well as processing modifications, little attention has been paid to its polymerization mechanism. Herein, the influence of temperature and time on PA56's polycondensation reaction is detailed studied by end-group titration and carbon nuclear magnetic resonance (NMR) techniques. The reaction kinetics equations for the pre-polymerization and vacuum melt-polymerization stages of PA56 are established, and possible side reactions during the polycondensation process are analyzed. By optimizing the reaction process based on kinetic characteristics, PA56 resin with superior comprehensive properties (melting temperature of 252.6 °C, degradation temperature of 371.6 °C, and tensile strength of 75 MPa) is obtained. The findings provide theoretical support for the industrial production of high-quality biobased PA56.

Conjugated Polymers from Direct Arylation Polycondensation of 3,4-Difluorothiophene-Substituted Aryls: Synthesis and Properties.

3,4-Difluorothiophene-substituted aryls, i.e., 1,4-bis(3,4-difluorothiophen-2-yl)-benzene (Ph-2FTh), 1,4-bis(3,4-difluorothiophen-2-yl)-2,5-difluorobenzene (2FPh-2FTh), and 4,7-bis(3,4-difluorothiophen-2-yl)-2,1,3-benzothiadiazole (BTz-2FTh), are synthesized as C─H monomers for the synthesis of conjugated polymers (CPs) via direct arylation polycondensation (DArP) with diketopyrrolopyrrole (DPP) and isoindigo (IID) derivatives as C─Br monomers. The Gibbs free energies of activation for direct arylation (ΔG298 K , kcal mol-1 ) for α─C─H bonds of thiophene moieties as calculated by density functional theory (DFT) are 14.3, 16.5, and 16.4 kcal mol-1 for Ph-2FTh, 2FPh-2FTh and BTz-2FTh, respectively, meaning that inserting an electron-deficient unit in 3,3',4,4'-tetrafluoro-2,2'-bithiophene (4FBT, ΔG298K : 14.6 kcal mol-1 ) may cause a reactivity decrease of the C─H monomers. Photophysical and semiconducting properties of the resulting six CPs (i.e., DPP-Ph, DPP-2FPh, DPP-BTz, 2FIID-Ph, 2FIID-2FPh, and 2FIID-BTz) are characterized in detail. DPP-based CPs show ambipolar transport properties while IID-based ones exhibited n-type behavior owing to the deeper frontier molecular orbital energy levels of IID-based CPs. With source/drain electrodes modified with polyethylenimine ethoxylated, n-channel organic thin-film transistors with maximum electron mobility of 0.40, 0.54, 0.29, 0.05, 0.16, and 0.01 cm2 V-1 s-1 for DPP-Ph, DPP-2FPh, DPP-BTz, 2FIID-Ph, 2FIID-2FPh, and 2FIID-BTz, respectively, are fabricated. DPP-2FPh exhibits the best device performance due to the good film morphology and the highest intermolecular packing order.

Green Synthesis of Soluble Polysilsesquioxane with Phthalimide Groups.

Soluble polysilsesquioxane containing side-chain phthalimide groups (PSQ-PhI) was synthesized via a solvent- and catalyst-free hydrolytic polycondensation reaction using 2-[3-(triethoxysilyl)propyl]-1H-isoindole-1,3(2H)-dione. The composition and structure of polysilsesquioxane was confirmed via 1H, 13C, and 29Si NMR spectroscopy, Fourier transform infrared spectroscopy, gel permeation chromatography, thermogravimetric analysis, dynamic light scattering, X-ray diffraction analysis, and elemental analysis. The synthesized silsesquioxane showed a monomodal molecular weight distribution. The average molecular weight of polysilsesquioxane is 11,200 Da, and the polydispersity index is 1.10. 29Si NMR analysis showed a half-peak width w1/2 3.1 ppm at δ -68.3, which corresponds to the PhI(CH2)3SiO3/2 unit and indicates an ordered structure in the polymer, with some defects caused by the presence of uncondensed silanol groups. PSQ-PhI showed good thermal stability (Td5% decomposition at 345 °C). The polysilsesquioxane-based coating was transparent in the visible region.

Design, Synthesis and Actual Applications of the Polymers Containing Acidic P-OH Fragments: Part 2-Sidechain Phosphorus-Containing Polyacids.

Macromolecules containing acidic fragments in side-groups­polyacids­occupy a special place among synthetic polymers. Properties and applications of polyacids are directly related to the chemical structure of macromolecules: the nature of the acidic groups, polymer backbone, and spacers between the main chain and acidic groups. The chemical nature of the phosphorus results in the diversity of acidic >P(O)OH fragments in sidechain phosphorus-containing polyacids (PCPAs) that can be derivatives of phosphoric or phosphinic acids. Sidechain PCPAs have many similarities with other polyacids. However, due to the relatively high acidity of −P(O)(OH)2 fragment, bone and mineral affinity, and biocompatibility, sidechain PCPAs have immense potential for diverse applications. Synthetic approaches to sidechain PCPAs also have their own specifics. All these issues are discussed in the present review.

Covalent Scrambling in Porous Polyarylthioethers through a Stepwise SN Ar for Tunable Bandgap and Porosity.

Porous poly(aryl thioether)s offer stability and electronic tunability by robust sulfur-aryl conjugated architecture, but synthetic access is hindered due to limited control over the nucleophilic nature of sulfides and the air sensitivity of aromatic thiols. Here, we report a simple, one-pot, inexpensive, regioselective synthesis of highly porous poly(aryl thioether)s through polycondensation of perfluoroaromatic compounds with sodium sulfide. The unprecedented temperature-dependent para-directing formation of thioether linkages leads to a stepwise transition of the polymer extension into a network, thereby allowing fine control of the porosity and optical band gaps. The obtained porous organic polymers with ultra-microporosity (<1 nm) and sulfur as the surface functional groups show size-dependent separation of organic micropollutants and selective removal of mercury ions from water. Our findings offer easy access to poly(aryl thioether)s with accessible sulfur functionalities and higher complexity, which will help in realizing advanced synthetic designs in applications such as adsorption, (photo)catalysis, and (opto)electronics.

A High-Performance n-Type Thermoelectric Polymer from C-H/C-H Oxidative Direct Arylation Polycondensation.

n-Type conjugated polymers (CPs) are crucial in the applications of organic electronics. Direct coupling of electron-deficient C-H monomer via selective C-H activation, namely C-H/C-H oxidative direct arylation polycondensation (Oxi-DArP), is an ideal approach toward such CPs. Herein, Oxi-DArP is firstly adopted to synthesize a high-performance n-type CP using a newly developed monomer, i.e., 3,6-di(thiazol-5-yl)-diketopyrrolopyrrole (Tz-5-DPP). Tz-5-DPP based homopolymer PTz-5-DPP with a molecular weight of 22 kDa has been synthesized via Oxi-DArP. After n-doping, PTz-5-DPP films exhibited electric conductivity values up to 8 S cm-1 and power factors (PFs) up to 106 µW m-1 K-2 . Notably, this PF value is the highest for n-type polymer thermoelectric materials to date. The Oxi-DArP synthesis and the excellent n-type performance of the polymer make this work an important step toward the straightforward and sustainable preparation of high-performance n-type polymer semiconductors.

An Efficient Direct Arylation Polycondensation via C-S Bond Cleavage.

The direct arylation polycondensation (DArP) has become one of the most important methods to construct conjugated polymers (CPs). However, the homocoupling side-reactions of aryl halides and the low regioseletive reactivities of unfunctionalized aryls hinder the development of DArP. Here, an efficient Pd and Cu co-catalyzed DArP was developed via inert C-S bond cleavage of aryl thioethers, of which robustness was exemplified by over twenty conjugated polymers (CPs), including copolymers, homopolymers, and random polymers. The capture of oxidative addition intermediate together with experimental and theoretic results suggested the important role of palladium (Pd) and copper (Cu) co-catalysis with a bicyclic mechanism. The studies of NMR, molecular weights, trap densities, two-dimensional grazing-incidence wide-angle X-ray scattering (2D-GIWAXS), and the charge transport mobilities revealed that the homocoupling reactions were significantly suppressed with high regioselectivity of unfunctionalized aryls, suggesting this method is an excellent choice for synthesizing high performance CPs.

Non-Isocyanate Aliphatic-Aromatic Poly(carbonate-urethane)s-An Insight into Transurethanization Reactions and Structure-Property Relationships.

This study reveals insights into the transurethanization reactions leading to the aliphatic-aromatic non-isocyanate poly(carbonate-urethane)s (NIPCUs) and their structure-property relationships. The crucial impact of the alkyl chain length in 4,4'-diphenylmethylene bis(hydroxyalkyl carbamate) (BHAC) on the process of transurethanization reactions was proved. The strong susceptibility of hydroxyethyl- and hydroxybutyl carbamate moieties to the back-biting side reactions was observed due to the formation of thermodynamically stable cyclic products and urea bonds in the BHACs and NIPCUs. When longer alkyl chains (hydroxypentyl-, hydroxyhexyl-, or hydroxydecyl carbamate) were introduced into the BHAC structure, it was not prone to the back-biting side reaction. Both 1H and 13C NMR, as well as FT-IR spectroscopies, confirmed the presence of carbonate and urethane (and urea for some of the samples) bonds in the NIPCUs, as well as proved the lack of allophanate and ether groups. The increase in the alkyl chain length (from 5 to 10 carbon atoms) between urethane groups in the NIPCU hard segments resulted in the increase in the elongation at break and crystalline phase content, as well as the decrease in the Tg, tensile strength, and hardness. Moreover, the obtained NIPCUs exhibited exceptional mechanical properties (e.g., tensile strength of 40 MPa and elongation at break of 130%).

Poly(Butylene Adipate/Terephthalate-Co-Glycolate) Copolyester Synthesis Based on Methyl Glycolate with Improved Barrier Properties: From Synthesis to Structure-Property.

The main problem of manufacturing with traditional biodegradable plastics is that it is more expensive than manufacturing with polymers derived from petroleum, and the application scope is currently limited due to poor comprehensive performance. In this study, a novel biodegradable poly(butylene adipic acid/terephthalate-co-glycolic acid) (PBATGA) copolyester with 25-60% glycolic acid units was successfully synthesized by esterification and polycondensation using cheap coal chemical byproduct methyl glycolate instead of expensive glycolic acid. The structure of the copolyester was characterized by ATR-FTIR, 1H NMR, DSC, and XRD; and its barrier property, water contact angle, heat resistance, and mechanical properties were tested. According to the experiment result, the PBATGA copolyesters showed improved oxygen (O2) and water vapor barrier character, and better hydrophilicity when compared with PBAT. The crystallization peaks of PBATGAs were elevated from 64 °C to 77 °C when the content of the GA unit was 25 mol %, meanwhile, the elongation at the break of PBATGA25 was more than 1300%. These results indicate that PBATGA copolyesters have good potentiality in high O2 and water vapor barrier and degradable packaging material.

Polycondensed Peptide Carriers Modified with Cyclic RGD Ligand for Targeted Suicide Gene Delivery to Uterine Fibroid Cells.

Suicide gene therapy was suggested as a possible strategy for the treatment of uterine fibroids (UFs), which are the most common benign tumors inwomen of reproductive age. For successful suicide gene therapy, DNAtherapeutics should be specifically delivered to UF cells. Peptide carriers are promising non-viral gene delivery systems that can be easily modified with ligands and other biomolecules to overcome DNA transfer barriers. Here we designed polycondensed peptide carriers modified with a cyclic RGD moiety for targeted DNA delivery to UF cells. Molecular weights of the resultant polymers were determined, and inclusion of the ligand was confirmed by MALDI-TOF. The physicochemical properties of the polyplexes, as well as cellular DNA transport, toxicity, and transfection efficiency were studied, and the specificity of αvß3 integrin-expressing cell transfection was proved. The modification with the ligand resulted in a three-fold increase of transfection efficiency. Modeling of the suicide gene therapy by transferring the HSV-TK suicide gene to primary cells obtained from myomatous nodes of uterine leiomyoma patients was carried out. We observed up to a 2.3-fold decrease in proliferative activity after ganciclovir treatment of the transfected cells. Pro- and anti-apoptotic gene expression analysis confirmed our findings that the developed polyplexes stimulate UF cell death in a suicide-specific manner.