Carbonization of Carboxylate‐Functionalized Polymers of Intrinsic Microporosity for Water Treatment

Considering the variations in their pore characteristics and heterogeneity, the carbonization process of carboxylate‐functionalized polymers of intrinsic microporosity (PIM‐COOH) is investigated and the resulted membranes are tested for water treatment. The four distinct types of sub‐nanosized membranes with different oxygen‐to‐carbon ratios are prepared at four different temperatures: the pristine polymer membrane, crosslinked membrane via thermal decarboxylation, amorphous carbon membrane, and graphitic carbon membrane. Notably, the sub‐1 nm micropores of all the heat‐treated samples that do not exhibit a broadening pore size distribution are still retained. Nanofiltration performance is investigated using an aqueous MgSO₄ solution (2000 ppm), pure water, and a series of the defect‐free, sub‐1 nm microporous membranes. While retaining the salt rejection, the water flux of the membranes increases with the pyrolysis temperature owing to their low friction property.     

Fabrication of Thermally Crosslinked Hydrolyzed Polymers of Intrinsic Microporosity (HPIM)/Polybenzoxazine Electrospun Nanofibrous Membranes

In this study, thermally crosslinked hydrolyzed polymers of intrinsic microporosity (HPIM)/polybenzoxazine electrospun nanofibrous membranes (NFMs) are successfully produced. The nanofibers having 800 ± 260 to 670 ± 150 nm average fiber diameters from HPIM and blends of HPIM/ benzoxazine (BA‐a) ranging from HPIM:(BA‐a) weight ratio of 9:1 to 2:1 w/w are produced by electrospinning. Self‐standing HPIM/(BA‐a) NFMs are thermally step‐wise cured resulting in crosslinked HPIM/Poly(BA‐a) NFMs. Structural characterization of as‐electrospun HPIM/(BA‐a) and crosslinked HPIM/Poly(BA‐a) NFM is conducted by FT‐IR spectroscopy to trace the ring opening and crosslinking reactions. Elemental analysis and XPS studies show an increase in carbon content and reduction in nitrogen content due to the crosslinking reaction. Decomposition temperature (T _d) of HPIM NFM increases from 218 to 270 °C with the crosslinking based on the DSC. DMA analysis shows that the mechanical strength of the NFMs has increased significantly with crosslinking. Young's moduli of HPIM NFM is increased from 16 ± 7 to 67 ± 1 MPa for crosslinked HPIM/Poly(BA‐a)%33 NFM. Similarly, higher storage modulus is observed for HPIM/Poly(BA‐a) NFMs compared to HPIM NFM. The crosslinked HPIM/Poly(BA‐a) NFMs keep their fibrous morphology after solvent treatment in dimethylformamide revealing their structural stability compared to pristine HPIM NFM.     

Influence of Branching of Polythiophenes on the Microporosity

A chain growth polymerization of a branched polythiophene (BT) using a Pd(Ruphos) catalyst, as a promising route to synthesize microporous conjugated polymers with well‐defined structures is reported. From N₂ adsorptions/desorption isotherm measurements, a Brunauer–Emmett–Teller surface area of 40.7 m² g^?1 is calculated for the BT, significantly higher than that of the linear poly(3‐hexylthiophene) (P3HT) (25.7 m² g^?1). The same trend is confirmed by simulations of the two polymer structures, from which a geometric surface area (SA_geo) of 140 ± 15.8 m² g^?1 is calculated for the BT, much more higher than for the P3HT with a SA_geo of 6.7 ± 7.1 m² g^?1. Moreover, the BT is soluble in common organic solvent and is readily processed in membrane with a CO₂/N₂ selectivity up to 24.     

Preparation and Gas Separation Properties of Triptycene‐Based Microporous Polyimide

Polyimides with intrinsic microporosity (PIM‐PIs) are widely regarded as one of the most promising next‐generation membrane materials to simultaneously achieve high permeability and selectivity. Despite the fact that tremendous microporous polyimides have been synthesized, only cost‐ef?cient PIM‐PIs have the potential to be used in industrial applications. In this work, a PIM‐PI is prepared by using the commercial and inexpensive planar pyromellitic dianhydride (PMDA) as the dianhydride monomer, and 2,6‐diaminotriptycene as the diamine monomer. The CO₂ permeability of PMDA‐DAT is ≈23‐fold higher than that of Kapton, one of the commercially available polyimide membranes also made from PMDA, and with almost the same CO₂/CH₄ selectivity. In addition, no plasticization phenomenon is observed for PMDA‐DAT membrane even at a CO₂ pressure up to 15 atm. The good plasticization resistance performance of PMDA‐DAT can be mainly attributed to the formation of pseudo‐physical crosslinking by interlocking and π–π interactions in triptycene moieties.     

Synthesis and Properties of 6FDA‐MDA Copolyimide Membranes: Effects of Diamines and Dianhydrides on Gas Separation and Pervaporation Properties

6FDA‐MDA‐based polyimides were synthesized from a one‐step polycondensation of 6FDA and MDA with other diamines and dianhydrides. The polyimides were characterized by GPC, FT‐IR and NMR, and dense membranes were prepared from their solutions for gas separation and pervaporation. Gas separation and pervaporation properties were investigated using the linear moiety contribution method. The moiety contribution factors were used to analyze the effects of the dianhydride and diamine monomers on gas permselectivity and pervaporation permeation flux. It was shown that the steric effects and flexibility of the monomers and the interactions between the membrane and the penetrants accounted for the differences in separation properties.

     

Synthesis and Gas Permeability of Chemically Cross‐Linked Polynorbornene Dicarboximides Bearing Fluorinated Moieties

This work reports on the synthesis of a novel bifunctional norbornene dicarboximide monomer (HFDA) based on 4,4′‐(hexafluoroisopropylidene)bis(p‐phenyleneoxy)dianiline and its application as a cross‐linking agent in the ring‐opening metathesis polymerization (ROMP) with N‐3‐trifluoromethylphenyl‐exo,endo‐norbornene‐5,6‐dicarboximide (mCF₃) employing the Grubbs 2nd generation catalyst (I) and cis‐1,4‐diacetoxy‐2‐butene as a chain transfer agent (CTA) to yield a series of soluble nonlinear highly branched chains polymers with increasing degree of cross‐linking. A comparative study of gas transport in membranes based on these cross‐linked polynorbornene dicarboximides is performed and the gases studied are hydrogen, oxygen, nitrogen, carbon dioxide, methane, ethylene, and propylene. It is found that cross‐linking increases the gas permeability, leads to the highest separation factor reported to date for the H₂/C₃H₆ mixture in this kind of polymers, and also enhances the CO₂ plasticization resistance up to 14 atm upstream pressure. The chemical cross‐linking approach employed in this research is an effective tool to enhance gas transport properties for dense polynorbornene dicarboximide membranes.     

Synthesis and Fluorescence Properties of Chiral Near‐Infrared Emissive Polymers Incorporating BODIPY Derivatives and (S)‐Binaphthyl

A new series of π‐conjugated chiroptical polymers consisting of styryl BODIPYs moieties and (S)‐binaphthyl units has been firstly synthesized via Sonogashira polymerization. The resulting polymers were characterized by ¹H NMR spectroscopy, gel permeation chromatography (GPC), UV–Vis absorption spectroscopy, cyclic voltammetry (CV), circular dichroism (CD), and density functional theory (DFT) calculations. The chiral polymers have moderate molecular weights, high solubility in commonly solvents and stable chiroptical conformation. And more importantly, the four chiral polymers can exhibit near‐infrared (NIR) emissive and good anisotropic fluorescence. We anticipate these chiral NIR polymers will be useful in biological measurements and cellular imaging where NIR emission is beneficial.     

Synthesis and Gas‐Transport Properties of Novel Copolymers Based on Tricyclononenes Containing One and Three Me3Si‐Groups

In this work the authors report the preparation of new addition copolymers based on 3‐trimethylsilyltricyclononene‐7 (TCNSi1) and 3,3,4‐tris(trimethylsilyl)tricyclononene‐7 (TCNSi3). A number of high molecular weight copolymers are synthesized with the content of TCNSi3 units from 5 up to 20 mol% in the presence of catalyst Pd(OAc)₂/[Ph₃C]⁺[B(C₆F₅)₄]⁻ with the yields of 50%–80%. The obtained copolymers are amorphous. They possess large free volume elements (R ₃/R ₄) based on positron annihilating lifetime spectroscopy analysis and Brunauer–Emmett–Teller surface area up to 640 m² g⁻¹. Permeability coefficients of the obtained copolymers are determined for a wide range of gases He, H₂, O₂, N₂, CO₂, CH₄, C₂H₆, C₃H₈, n‐ C₄H₁₀. The correlation between the content of TCNSi3 units and gas permeation parameters of the resulting copolymers is explored. It is found that the introduction of TCNSi3 moieties results in the rise in gas permeability of the corresponding copolymers. Moreover, increase in TCNSi3 content in the copolymer leads to an increase of gas permeability.

     

Synthesis of High‐Molecular Weight Polymers Based on N,N‐Diallyl‐N‐Methylamine

High‐molecular weight polymers, namely poly(N,N‐diallyl‐N‐methylammonium trifluoroacetate) and poly(N,N‐diallyl‐N‐methylamine), were prepared by radical polymerization of N,N‐diallyl‐N‐methylamine in aqueous solution in the presence of an equimolar amount of trifluoroacetic acid and by polymerization of the newly synthesized equimolecular salt N,N‐diallyl‐N‐methylammonium trifluoroacetate in gentle conditions. We have established that chain termination is controlled by the bimolecular mechanism and that degradative chain transfer to monomer transforms into effective chain transfer (see Scheme). The possibility of controlling the polymerization rate and molecular weight of polymers is demonstrated. The mechanisms of the observed phenomena are discussed.

     

Synthesis and Characterization of Isoindigo‐Based Polymers with Thermocleavable Side Chains

Stability of bulk heterojunction films for organic solar cells is a critical factor for commercial viability. One method to stabilize these films is to include cleavable side chains, which reduce the solubility of the polymers when removed. In order to study the stabilizing effect of cleavable side chains, a series of random copolymers using isoindigo with 0, 10, 20, 50, and 100% thermally cleavable side chains based on the tert‐butyloxycarbonyl (t‐BOC) group are synthesized. The polymers show a distinct one‐step thermal cleavage of the side chains, with no separable dealkylation and decarboxylation steps. The thermal stability in film is studied with transmission electron microscopy and atomic force microscopy. The polymer with all t‐BOC side chains on isoindigo significantly improves thermal stability with regard to crystal growth and phase separation in film. These results suggest BOC‐substitution can be used for large scale processing to produce insoluble polymer films with a high degree of thermal stability.     

Plant Oil‐Based Long‐Chain C26 Monomers and Their Polymers

The self‐metathesis of erucic acid with ruthenium‐based catalysts, followed by the hydrogenation of the double bond, yielded 1,26‐hexacosanedioic acid ( AA ). Polycondensation of this biobased long‐chain α,ω‐dicarboxylic acid with hexacosane‐1,26‐diol ( BB ), generated from the former by reduction, yielded the polyester 26,26. Monomer AA was also polymerized with short‐chain alkanediols, namely dodecane‐1,12‐diol and butane‐1,4‐diol, generating polyesters 12,26 and 4,26, respectively. The properties of these aliphatic polyesters were investigated by various techniques, revealing high crystallinity, melting, and degradation temperatures, depending on the monomers used. These materials are an attractive alternative to fossil resource‐based polymeric materials.     

Synthesis and Characterization of Functional Triphenylphosphine‐Containing Microporous Organic Polymers for Gas Storage and Separation

Two kinds of novel triphenylphosphine‐containing microporous organic polymers are designed and synthesized via palladium‐catalyzed Sonogashira−Hagihara coupling condensation reaction of triphenylphosphine oxide‐ and sulfide‐based monomers with different arylethynylene linkers. The gas adsorption isotherms reveal that these polymers have strong binding affinity for CO₂ with high CO₂ adsorption capacity, although they have moderate Brunauer−Emmett−Teller surface area ranging from 684 to 883 m² g⁻¹. Among the resulting polymers, triphenylphosphine oxide–tris(4‐ethynylphenyl)amine exhibits the highest CO₂ uptake capacity of 2.61 mmol g⁻¹ at 273 K and 1.13 bar with relatively high gas selectivity of 60.2 for CO₂ over N₂ at 273 K.     

A New Class of Organosoluble Rigid‐Rod Fully Aromatic Poly(1,3,4‐oxadiazole)s and Their Solid‐State Properties, 1. Synthesis

Since it is known, that poly(p‐phenylene‐1,3,4‐oxadiazole) exhibits reversible reduction behaviour in cyclovoltammetric measurements, it may be used as an electron transport material in electronic devices such as light emitting diodes (LEDs). However, the polymers are difficult to process, for example as thin films. By introducing linear or branched alkoxy side groups into the backbone it is possible to obtain rigid rod, fully aromatic poly(1,3,4‐oxadiazole)s which are soluble in organic solvents. Various polycondensation routes were investigated to prepare symmetrical and unsymmetrical dialkoxy‐substituted aromatic poly(1,3,4‐oxadiazole)s. Initially the interfacial polycondensation and the low‐temperature solution polycondensation between aromatic dihydrazides and diacid chlorides in N‐methylpyrrolidone were used. These methods were not successful for the synthesis of the polyoxadiazole with branched side chains. Thus, a new synthetic method for the preparation of such polymers was developed. The polycondensations are carried out in hot 1,2‐dichlorobenzene in the presence of a basic acceptor like pyridine. These conditions are unusual for such types of reaction.     

Preparation and Gas Separation Properties of Spirobichroman‐Based Polyimides

Polymers with rigid and contorted structures are always preferred for use as gas separation membranes. Owing to the contorted nature of the spiro‐center, the spirobichroman structure is an effective scaffold for impeding polymer chain packing. Two spirobichroman‐based diamines, 6,6′‐bis(4‐amino‐2‐trifluoromethylphenoxy)‐4,4,4′,4′,7,7′‐hexamethyl‐2,2′‐spirobichroman (FSBC) and 6,6′‐bis(4‐aminophenoxy)‐4,4,4′,4′,7,7′‐hexamethyl‐2,2′‐spirobichroman (SBC), with or without CF₃ side groups are prepared. The two diamines are separately reacted with 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride (BTDA) and 3,3′,4,4′‐diphenylsulfonetetracarboxylic dianhydride (DSDA) to obtain four spirobichroman‐based polyimides, denoted as BTDA‐FSBC, BTDA‐SBC, DSDA‐FSBC, and DSDA‐SBC. The different molecular structures among the four monomers are expected to alter the fractional free volume of the corresponding polyimides by impacting chain‐packing conditions, and then controlling the gas transport properties. Chemical structures, thermal and physical properties of the polyimides are fully characterized. Two different methods, molecular dynamics simulation and Bondi's group contribution method are employed to characterize the fractional free volumes (FFVs) of these polyimides. In the end, it is found that FSBC‐based polyimides exhibit relatively higher gas permeability than SBC‐based polyimides.     

Synthesis and Photovoltaic Properties of Side‐Chain Liquid‐Crystal Click Polymers for Dye‐Sensitized Solar‐Cells Application

SCLCPs are synthesized using “click chemistry”. The resulting polymers, P1 and P2, have good solubilities and molecular‐weight distributions. Their and polydispersities are in the ranges of 26.7–8.4 × 10³ g · mol^?1 and 1.99–1.29, respectively. DSC and POM studies reveal that both polymers exhibit liquid‐crystalline behavior. P1 and P2 are found to display blue emission. DSSCs are fabricated using P1 and P2 as matrices for electrolytes. The maximum PCE of the P1‐ and P2‐based polymer electrolytes is 4.11% (at 1 sun). This synthesis route has again proven to be a useful synthetic methodology for fabricating SCLCPs that are promising materials for device applications.

     

Electrical Properties of Magnetoactive Boron‐Organo‐Silicon Oxide Polymers

The electrical properties of rheopectic magnetoactive composites comprising boron‐organo‐silicon oxide dielectric matrices containing carbonyl iron microparticles are presented for the first time. The increase in interfacial magnetocapacitance is seen to greatly exceed that experienced when using conventional elastomeric matrices such as polydimethylsiloxane. In addition to the increase in capacitance, a simultaneous and sharp decrease in the parallel electrical resistance over several orders of magnitude is also observed. The effects are time dependent but repeatable. Potential applications include magnetically controlled frequency dependent devices, magnetic sensor systems, weighting elements for neural networks, etc.     

A Multi‐Structural Model for Prediction of Effective Gas Permeability in Mixed‐Matrix Membranes

A new model for prediction of the effective permeability of gases in mixed matrix membranes (MMMs), considering the effects of particle shape and the interfacial layer, is presented. The proposed model treats core filler particles and interfacial shell layers as complex particles. Moreover, the Bruggman mathematical procedure is used to improve the accuracy of the presented model for high concentrations of fillers in MMMs. Also, an appropriate uniform criterion is established to make efficient use of the new model for various experimental data to avoid the need for curve‐fitting procedures. Finally, the proposed model is examined for several sets of experimental data.

     

Synthesis and Properties of a High‐Temperature Naphthyl‐Based Phthalonitrile Polymer

A novel, high‐temperature, naphthyl‐based phthalonitrile polymer is prepared. The phthalonitrile monomer, namely, 2,7‐bis(3,4‐dicyanophenoxy) naphthalene (BDCN), is synthesized from the reaction of 2,7‐dihydroxynaphthalene (DHN) with 4‐nitrophthalonitrile (NPN), and its curing behavior with 1,3‐bis(4‐aminophenoxy) benzene (APB) is investigated by DSC. The high‐temperature BDCN polymer is prepared via a two‐step approach: the preparation of the BDCN prepolymer and the post‐cure of the BDCN prepolymer at elevated temperatures. The BDCN polymer might form a polypyrrole structure as revealed by FTIR spectroscopy, and exhibits a high storage modulus, high glass‐transition temperature, and outstanding thermal stability, along with long‐term oxidative resistance.     

Synthesis of Branched Polymers by Means of Living Anionic Polymerization, 9. Radical Coupling Reaction of 1,1‐Diphenylethylene‐Functionalized Polymers with Potassium Naphthalenide and Its Application to Syntheses of In‐Chain‐Functionalized Polymers and Star‐Branched Polymers

Radical coupling reactions of both 1,1‐diphenylethylene (DPE)‐chain‐end‐ and DPE‐in‐chain‐functionalized polymers with potassium naphthalenide have been studied under the conditions mainly in THF at –78°C. Chain‐end‐functionalized polymers having M̄_n values of less than 10 kg/mol were very efficiently coupled in more than 90% yield to afford the polymeric dianion that were dimeric coupled products with two 1,1‐diphenylalkyl anions in the middle of the chains. However, the dimer yield decreased with increasing the molecular weight. The dimer was obtained in 59% yield with use of the chain‐end‐functionalized polymer having M̄_n of 33.9 kg/mol. Well‐defined in‐chain‐functionalized polymers with two benzyl bromide and DPE moieties each have been successfully synthesized by the reaction of the polymeric dianion thus obtained with 1‐(4‐bromobutyl)‐4‐(tert‐butyldimethylsilyloxymethyl)benzene and 1‐[4‐(4‐bromobutyl)phenyl]‐1‐phenylethylene, respectively. The radical coupling reaction of in‐chain‐functionalized polymers with DPE (M̄_n ca. 20 kg/mol) with potassium naphthalenide also proceeded efficiently to afford the coupled products that were A₂A′₂ and A₂B₂ four‐arm star‐branched polymers with well‐defined structures (M̄_n ca. 40 kg/mol).     

Bisfuran‐s‐Tetrazine‐Based Conjugated Polymers: Synthesis,Characterization, and Photovoltaic Properties

Bisfuran‐s‐tetrazine (FTz) and its copolymers with cyclopenta[2,1‐b:3,4‐b′]dithiophene (CPDT) and benzo[1,2‐b:4,5‐b′]dithiophene (BDT) (PCPDTFTz and PBDTFTz) are prepared with the alternating s‐tetrazine and CPDT or BDT units bridged by a furan ring. Their optical and electrochemical properties are studied and compared with their thiophene analogs (PCPDTTTz‐out and PCPDTTTz‐in), in which the bridging unit is 4‐hexylthiophene or 3‐hexylthiophene, respectively. Bulk heterojunction (BHJ) solar cells fabricated from these polymers with PC₇₁BM have a power conversion efficiency (PCE) of 0.8%, which is much lower than that from the PCPDTTTz‐out analog (3.2%), due to the low steric hindrance of the furan polymers in the absence of alkyl substitution on the furan ring.