Monomer M1 Research Articles

Poly[2]catenane Gels Based on Sequential Assembly of Small Molecules†

Comprehensive SummaryPolycatenane gels have attracted extensive attention due to their high degree of freedom and mobility. However, the syntheses of poly[2]catenane gels reported to date all rely on the polymer as the backbone. Herein, we prepared poly[2]catenane gels based on entirely sequential assembly of small molecules. Monomer M1 with two unclosed rings was first prepared, which self‐assembled to form supramolecular polymers (SPs) via hydrogen bonding and π‐π interactions. Upon adding small molecule monomers M2 and M3 with aldehyde groups, ring closing of SPs occurred because the amino groups in the SPs reacted with M2 to form imine bonds. In addition, M3, which had twice the number of aldehyde groups as M2, enabled SPs to ring‐close, causing the proceeding of crosslinking process at the same time. Thus linear SPs were transformed into poly[2]catenane gel networks. Due to the presence of hydrogen bonds in the poly[2]catenane gel, the gel also possessed stimulus responsiveness and self‐healing properties.

Biomass Modifiers for Low Dielectric Bismaleimides at High-Frequency

Two fluoro-containing monomers M1 and M2 derived from bio-based eugenol and estragole were designed and successfully synthesized via a facile one-step reaction. These monomers were copolymerized with commercial bismaleimide (BMI) in different molar ratios to give a series of BMI polymers. The properties of polymers were investigated to explore the effects of the modifiers on the thermostability, hydrophobicity, and dielectric properties of the BMIs. The BMI polymer incorporated with M2 showed a low dielectric content (Dk) of 2.89 and a dielectric loss (Df) of 6.1 × 10–3 at a high frequency of 10 GHz. Moreover, it displayed good hydrophobicity with a water uptake of 0.88% and excellent thermostability with a high 5% weight loss temperature (T5d) of 468 °C and a glass transition temperature (Tg) higher than 400 °C. The comprehensive properties are better than those of the allyl-modified maleimide resins (bismaleimide modified by diallyl bisphenol A, referred to as DABPA-BMI), which are widely used in the industry. This work provides a method to improve the properties of BMIs. The biomass monomers can be potentially used as modifiers to achieve low dielectric BMIs for high-frequency technology.

Synthesis and characterisation of novel aromatic ester swallow-tailed cholesteric liquid crystal polymers

ABSTRACT In this paper, two novel aromatic ester swallow-tailed liquid crystal monomers M1 and M2 and a straight chain cholesteric liquid crystal monomer M3 were designed and synthesised. Two series of liquid crystal polymers, P1 series and P2 series, were graft-copolymerised with M and polymethylhydrosiloxane (PHMS). All the synthesised liquid crystal monomers and polymers were characterised by IR and 1H NMR and confirmed to the predicted molecular structure. The liquid crystal and thermal properties of the synthesised compounds were tested by DSC, POM, TGA and optical rotation. The results show that the monomer M1 is a monotropic nematic liquid crystal, and the Schlieren texture appears during the cooling process. M2 is an enantiotropic nematic liquid crystal with filamentous and schlieren texture. M3 is a thermotropic enantiotropic cholesteric phase with oily streak and focal cone texture. Both polymers P1 and P2 show typical Grand-Jean texture, and with the increase of monomer M3 content, the polymer clearing point temperature Ti increases continuously, the liquid crystal mesophase range widens, and the specific rotation value increases.

A fluorescent controllable supramolecular crosslinked polymer constructed by complementary metal coordination interaction.

In this work, two different monomers M1 and M2 were designed and synthesized. M1 + M2 + Zn(OTf)2 could self-assemble to form a supramolecular crosslinked polymer (SCP) based on complementary terpyridine-based metal coordination interaction. The self-assembly of M1 + M2 + Zn(OTf)2 was studied by various techniques, such as 1H NMR, 2D COSY NMR, 2D NOESY NMR, UV-Vis analysis, fluorescence analysis, viscosity measurement, and TEM. The experimental result indicated that the molecular weight of the SCP depended on the initial monomer concentration. The SCP could further turn into supramolecular polymer gel at high concentrations, and the reversible gel-sol transformation could be realized by heating/cooling. Moreover, the fluorescence quenching/enhancement of the SCP could be adjusted by adding base/acid.

Utilizing a polymer containing squaramide-based ion pair receptors for salt extraction

Herein, we report a novel polymer containing synthetic squaramide-based ion pair receptors, which effectively capture and remove sulfate salts from aqueous source phases during liquid–liquid extraction. The monomer M1 was synthesized in a modular fashion, assuring acidity of the anion binding domain and allowing the receptor to be incorporated into the polymer chain and then tested in ion pair binding studies using UV–vis and NMR spectroscopy. After the incorporation of the monomer M1 into the polystyrene polymer chain, its solubility was improved, and a system was developed to selectively remove sulfate ions from systems similar to those naturally occurring in the environment, i.e. among mixtures with other salts. To identify the polymer's salt binding mechanism, additional solid–liquid extractions (SLE) were carried out, which were characterized using 1H NMR, thermal analyses (DSC and TGA) and Scanning Electron Microscopy (SEM).

Metal-Ligand Interactions and Oligo(p-phenylene vinylene) Derivatives Based Supramolecular Polymer Possessing Variable Fluorescence Colors.

Fluorescent supramolecular polymers combine the benefits of supramolecular polymers in terms of dynamic nature with the optoelectronic features of incorporated fluorophores. However, the majority of fluorescent supramolecular polymers can only exhibit a single fluorescent state, restricting their applications. Incorporating J-type dyes into supramolecular monomers is expected to impart supramolecular polymers with variable fluorescence colors, because the aggregation mode of J-type dyes is closely related to the formation of supramolecular polymers. Herein, the authors report a supramolecular polymer [M1·Zn(OTf)2 ]n , in which the monomer M1 contains a J-type dye, oligo(p-phenylene vinylene) derivative, and two terpyridine ends. The M1 + Zn(OTf)2 solutions exhibit fluorescence color changes varying from cyan to yellow-green in the monomer concentration ranging from 0.04 to 1.00mm. Moreover, based on the outputs from laser scanning confocal microscopy, the fluorescence color transition during the formation of supramolecular polymers is intuitively proven. Additionally, considering the close relationship between the supramolecular polymer structure and the fluorescence color, the fluorescence color can be regulated by introducing tetraethylammonium hydroxide that can bind with Zn2+ competitively to break up the structure of the supramolecular polymer.

A Strategy Based on Aggregation-Induced Ratiometric Emission to Differentiate Molecular Weight of Supramolecular Polymers.

Molecular weight has an important bearing on the properties of supramolecular polymers. However, the intuitive differentiation of the molecular weight of supramolecular polymers remains challenging. Given this situation, establishing a reliable relationship between fluorescence properties and molecular weight may be a promising strategy. Herein, we prepared a supramolecular monomer M1 with aggregation-induced ratiometric emission characteristics. With the increasing M1 concentration (0.100-100 mM), the average degree of polymerization (DPDOSY ) rose from 1.00 to 293. Meanwhile, the color changed from dark blue to cyan, finally to yellow-green in the same concentration range. Hence, the intuitive relationship between DPDOSY and fluorescence colors was constructed, allowing the visual differentiation of molecular weight. Moreover, the fluorescence color could be regulated by introducing a competitive molecule to induce the depolymerization of supramolecular polymers.

A Strategy Based on Aggregation‐Induced Ratiometric Emission to Differentiate Molecular Weight of Supramolecular Polymers

AbstractMolecular weight has an important bearing on the properties of supramolecular polymers. However, the intuitive differentiation of the molecular weight of supramolecular polymers remains challenging. Given this situation, establishing a reliable relationship between fluorescence properties and molecular weight may be a promising strategy. Herein, we prepared a supramolecular monomerM1with aggregation‐induced ratiometric emission characteristics. With the increasingM1concentration (0.100–100 mM), the average degree of polymerization (DPDOSY) rose from 1.00 to 293. Meanwhile, the color changed from dark blue to cyan, finally to yellow‐green in the same concentration range. Hence, the intuitive relationship between DPDOSYand fluorescence colors was constructed, allowing the visual differentiation of molecular weight. Moreover, the fluorescence color could be regulated by introducing a competitive molecule to induce the depolymerization of supramolecular polymers.

Living ring‐opening metathesis polymerization of norbornenes bay‐functionalized perylene diimides

AbstractRing‐opening metathesis polymerization (ROMP)‐derived poly(oxanorbornene imide)s bearing bay‐linked mono‐alkoxy‐M1 and 1,7‐di‐alkoxy M2 functionalized perylene diimides (PDIs) were synthesized using Grubb's third (G3) and Hoveyda‐Grubbs second generation (HG2) ruthenium‐alkylidene metathesis initiators. The mono‐alkoxy‐derived PDI‐based non‐ladderphane polymer polyM1 displayed 67% to 77% of the trans olefin content in the polymer chain depending on the initiator used for the polymerization. When using the symmetrical 1,7‐di‐alkoxy‐derived PDI‐based polymer polyM2 having the ladderphane type‐structure, this displayed a significant amount of cis and trans olefin contents in the polymer chains, irrespective of the type of initiators used for the polymerization. ROMP of both monomers M1 and M2 proceeded in a well‐controlled manner with a linear dependence of molecular weight on the monomer/initiator ratio using G3 as initiator. Optical properties of the ladderphane‐based polyM2 and non‐ladderphane‐based polyM1 were characterized in both solution and the film state. X‐ray diffraction (XRD) analysis for all the polymers showed significant π‐stacking in the thin film state with ordered molecular packing and closer values of d‐spacing for both polyM1 and polyM2. Film morphology examined by AFM elucidated homogenous smooth polymer surface for both polymers in general, but with some irregularities observed for polyM1. In addition, CV analysis revealed both polymers could be good candidates as electron‐accepting materials, with excellent film‐forming ability, and thermal stability.

Solvent-Free and Catalyst-Free Synthesis of Cross-Linkable Polyfumaramides via Topochemical Azide-Alkyne Cycloaddition Polymerization

Unsaturated polymers are important materials having a lot of applications. Among polymers, polyamides possess a prime position due to their thermal and chemical stability. Herein, we report a simple, greener, catalyst-free, and solid-state synthesis of two unsaturated polyamides via a topochemical azide-alkyne cycloaddition reaction. Two designed fumaramide monomers M1 and M2, functionalized with complementary azide and alkyne reactive motifs at the termini, reacted upon heating their crystalline powders and resulted in the formation of triazolyl-linked unsaturated polyfumaramides P1 and P2, respectively. We have characterized the reaction using various time-dependent techniques such as NMR, FTIR, PXRD, and DSC measurements. Interestingly, the monomer M1 resulted in 1,5-disubstituted triazole-linked unsaturated polyfumaramide (P1), whereas the monomer M2 polymerized into a polyfumaramide having both 1,4-disubstituted and 1,5-disubstituted triazole linkages (P2). Also, the trans-olefinic bond of both the fumaramide monomers was unaffected in the polymerization process and hence yielded unsaturated polymers having trans-olefin units in the repeating unit. Demonstrating the scope of postsynthetic modification, we have shown that unsaturation can be exploited for cross-linking via a light-induced [2 + 2] cycloaddition reaction. This first report on the solid-state synthesis of unsaturated polyfumaramides will be of great interest.

Developing luminescent ratiometric thermometers based on copolymers containing Platinum(II) isocyanide complex

Luminescent platinum(II) small molecules have aroused much attention due to their unique Pt(II)–Pt(II) interaction and intriguing luminescence properties; while incorporation of Pt(II) centers into polymers is still in its infancy. In this work, a class of random copolymers ((M1)x-co-(MPt)y; x = 200, y = 1, 2, 4) was synthesized by copolymerization of a newly designed norbornene-functionalized platinum(II) complex MPt and oligoethylene glycol modified monomer M1 using ROMP method. Compared to monomer MPt, the resulting polymers exhibit enhanced Pt(II)–Pt(II) interaction and intense low-energy emissions because of the confinement effect. Moreover, the photophysical properties of MPt and polymers ((M1)x-co-(MPt)y; x = 200, y = 1, 2, 4) were found to be highly dependent on the solvents and platinum(II) content in the polymers. Through switching on and off of the Pt(II)–Pt(II) interaction, (M1)200-co-(MPt)4 has been successfully demonstrated to be a self-referenced luminescent thermometer, which showed 2.11% K−1 (in TCE, 278K) relative temperature sensitivity, excellent reversibility and repeatability.

Design and synthesis of water-soluble chelating polymeric materials for heavy metal ion sequestration from aqueous waste

Sequestration and removal of dissolved heavy metal ions from aqueous waste streams is a challenging task. Ethylenediaminetetraacetic acid (EDTA) is a hexadentate chelating ligand capable of forming 1:1 complex with various heavy metal ions while iminodiacetic acid (IDA) is analogous to half a unit of EDTA. A new styrene based monomer M1 bearing dimethyl iminodiacetate group was designed and synthesized in good yield to meet this objective. Free radical polymerization of M1 generated the homopolymer, which upon base hydrolysis generated the water-soluble chelating homopolymer P10, bearing sodium salt of IDA as the chelating group. The overall yield of P10 was 76.80% and the solubility was 5 mg/mL at room temperature. The water soluble polymer P10 was investigated for its ability to bind various heavy metal ions by UV–vis spectroscopy and was found to efficiently sequester Cu2+, Cd2+, Zn2+, Pb2+, Ni2+, Co2+, Cr3+, Fe2+ and Fe3+. The effect of pH on Cu2+ binding with P10 showed that every two IDA bearing monomeric repeat units binds with one Cu2+ ion at pH 7 suggesting that it forms complexes analogous to EDTA. Thermogravimetric analysis showed that the synthesized polymer possesses high thermal stability up to 400 °C. The potential for recovery and reuse of the polymer has been demonstrated with Cu2+ ion. The reported results suggest that this water-soluble chelating homopolymer is an excellent material with very high potential for application in wastewater treatment.

Synthesis, Characterization and Electrochemical Properties of Polymers Based on Dithienothiophene and Bithiazole

AbstractConjugated polymers are promising cost‐effective, lightweight, and flexible electrode materials. 3,5‐Dinonyl‐2,6‐di(thiophene‐2‐yl)dithieno[3,2‐b : 2′,3′d]thiophene (M1) as a donor and 4,4′‐dinonyl‐5,5′‐di(thiophen‐2‐yl)‐2,2′‐bithiazole (M2) as an acceptor were synthesized and their polymers poly(3,5‐dinonyl‐2,6‐di(thiophene‐2‐yl)dithieno[3,2 b : 2′,3′‐d]thiophene) (P1) and poly(4,4′‐dinonyl‐5,5′‐di(thiophen‐2‐yl)‐2,2′‐bithiazole) (P2) were obtained via electropolymerization on ITO/glass electrode surface in ACN : DCM (1 : 3 v/v) solution, containing 0.1 M tetrabutylammonium hexafluorophosphate (TBAPF6). Then, a third polymer as a co‐polymer (P3) was synthesized through electropolymerization of a mixture of the monomers M1 and M2 in 1 : 1 ratio. All the polymers were characterized by UV‐Vis, CV and CV‐UV measurements. Moreover, capacitor properties of the polymers by potentiostatic electrochemical impedance spectroscopy (EIS) was performed. The polymers P1, P2 and P3 exhibited absorptions at 456, 453 and 519 nm in neutral state and their optical band gaps were determined to be 2.17, 2.53 and 1.95 eV, respectivetly. EIS measurements indicated that P3 had the highest current density, having lower resistance.

Bulk-synthesis and supercapacitive energy storage applications of nanoporous triazine-based graphdiyne

Heteroatom doping and well-tuned porosity are regarded as two important pathways to enhance energy storage performance of porous carbon materials (PCMs). In this context, N-doped triazine-based graphdiyne (TGDY) and its hydrogen-containing counterpart HGDY were bulk-synthesized by Glaser coupling reaction from multi-acetylene monomers M1 and M2 respectively. TGDY exhibits a two-dimensional layer-by-layer structure and a high specific BET surface area of 785 m2 g−1. After heat-treatment at an optimized temperature of 800 °C, TGDY-800 shows a high specific capacitance of 250 F g−1 at 0.1 A g−1 and a remarkable capacitance retention of 97.6% at 1 A g−1 after 10,000 cycles. These results are superior to HGDY-800 with similar structural skeleton and many other N-doped PCMs, indicating the synergetic effect of N-doping and high surface area. This work could effectively cast insight into designing of nanoporous carbon materials with good energy storage performance.

One-Pot Tandem Ring-Opening and Ring-Closing Metathesis Polymerization of Disubstituted Cyclopentenes Featuring a Terminal Alkyne Functionality

Tandem metathesis polymerization of terminal alkynes with a small functional ring-size cycloalkene remains a challenge. A series of 1-propargyl-1′-carboxylate ester monomers M1–M4 derived from 3-cy...

Fluorene-Based Donor-Acceptor Copolymers Containing Functionalized Benzotriazole Units: Tunable Emission and their Electrical Properties.

Monomers 4,7-dibromo-2H-benzo[d]1,2,3-triazole (m1) and 4,7-(bis(4-bromophenyl)ethynyl)-2H-benzo[d]1,2,3-triazole (m2) have been synthesized in good yields using different procedures. Monomers m1 and m2 have been employed for building new copolymers of fluorene derivatives by a Suzuki reaction under microwave irradiation using the same conditions. In each case different chain lengths have been achieved, while m1 gives rise to polymers for m2 oligomers have been obtained (with a number of monomer units lower than 7). Special interest has been paid to their photophysical properties due to excited state properties of these D-A units alternates, which have been investigated by density functional theory (DFT) calculations using two methods: (i) An oligomer approach and (ii) by periodic boundary conditions (PBC). It is highly remarkable the tunability of the photophysical properties as a function of the different monomer functionalization derived from 2H-benzo[d]1,2,3-triazole units. In fact, a strong modulation of the absorption and emission properties have been found by functionalizing the nitrogen N-2 of the benzotriazole units or by elongation of the π-conjugated core with the introduction of alkynylphenyl groups. Furthermore, the charge transport properties of these newly synthesized macromolecules have been approached by their implementation in organic field-effect transistors (OFETs) in order to assess their potential as active materials in organic optoelectronics.

Controlling Photocatalytic Reactions and Hot Electron Transfer by Rationally Designing Pore Sizes and Encapsulated Plasmonic Nanoparticle Numbers

Controlled self-assembly of different numbers of gold nanoparticles (AuNPs) in the highly ordered cylindrical anodic aluminum oxide nanopores was achieved by a facile ultrasonication method. The surface plasmon resonance bands became red-shifted by increasing the number of nanoparticles (N), in the top view, from monomer M1 (N = 1) to multimers of M2 (N = 3 ± 1), M3 (N = 5 ± 1), and M4 (N = 7 ± 1). The numerical calculations of the M2 model showed the best match of 2 nm nanogap among 28 nm diameter AuNPs in 53 nm diameter nanopores. When the number of AuNPs inside the nanopores increased, more hotspots were generated, which induced the plasmon-driven photocatalysis on AuNP clusters at the incident visible light of 633 nm. The enhanced photocatalytic reaction of 4-nitrobenzenethiol was observed after sequentially increasing the number of AuNPs, which began at M3 and was maximum for M4. The M3 configuration could be a magical number of AuNP clusters for the nanogap-induced photocatalysis under 633 nm irradiation (∼0.2 mW) for 12 min. Our methods should be helpful in adjusting photocatalysis by varying the numbers of nanoparticles inside the tunable nanopores.

Synthesis of thioether‐functional poly(olefin)s via ruthenium‐alkylidene initiated ring‐opening metathesis polymerization

ABSTRACTRing‐opening metathesis polymerization (ROMP) of thioether‐derived oxanorbornene imide (M1) and its copolymerization with various cycloolefin comonomers such as cyclopentene (M2), cyclopent‐3‐en‐1‐ol (M3), cycloheptene (M4), and cyclooctene (M5) using Hoveyda–Grubbs second generation catalyst has been investigated. Polymerizations were performed at two different temperatures (0 and 25 °C) and the obtained functional poly(olefin)s were characterized by nuclear magnetic resonance 1H and 13C (NMR), and infrared spectroscopy as well as size exclusion chromatography, differential scanning calorimetry, and thermogravimetric analysis analyses. Additionally, the dependence of the polymer composition on the reaction temperature and monomer feed was studied with time‐dependent 1H NMR experiments. Copolymerization of M1 with a five‐membered cycloolefin monomer M2 showed relatively low ROMP reactivity irrespective of the reaction conditions in comparison to M3, M4, and M5 monomers. In general, the degree of monomer incorporation into poly(olefin)s were determined in the order of M5 > M3 > M4 > M2, and that sheds light on the effect of cycloolefin ring strain energies in the ruthenium‐alkylidene initiated ROMP. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1741–1747

Synthesis and characterization of chiral azo LCPs with optical properties

ABSTRACTIn this study, we designed, synthesised and characterised two series of cholesteric liquid crystal polymers, QP series and ZP series. With polymethylhydrosiloxane as the main chain, QP series were synthesised by copolymerisation between the monomer M1 containing a cholesteryl mesogenic unit and the monomer M2 with a hydroxyl. ZP series, meanwhile, were synthesised by esterification between QP series members and the monomer M3, a carboxylic acid with an azo mesogenic unit. We characterised chemical structures of all the monomers and polymers by FT-IR and 1H-NMR, which proved that the target monomers and polymers had been obtained. We observed dramatic colour changes after the introduction of monomer M3 and Grandjean textures from both QP series and ZP series using POM. In addition, strong selective reflection could be observed as well. Then, we characterised the thermal properties of polymers by DSC, TGA and XRD to explore their phase transition behaviours further. Their photoresponsive and photochromic properties were characterised by UV-Vis spectrum.

Donor-Acceptor-Donor Copolymers with 3,4-Ethylenedioxythiophene Moiety: Electropolymerization and Effect on Optoelectronic and Electrochromic Properties.

Three random copolymers PE-co-M1, PE-co-M2, and PE-co-M3 were obtained by electrochemical polymerization of donor–acceptor–donor monomers M1, M2, and M3 with 3,4-ethylenedioxythiophene moiety, respectively, using a 1:1 molar ratio of the corresponding monomers, to find new properties and a more effective way to control the optoelectronic properties in conjugated system. For comparison purpose, polymers P1, P2, and P3 were prepared from the corresponding monomer units M1–M3, respectively, by electrochemical polymerization. We also present efficient synthesis, characterization, and comparative density functional theory (DFT) calculations of the monomers M1–M3 and polymers P1–P3. Cyclic voltammetry, spectroelectrochemistry, and electrochromic properties of all of the polymers P1–P3 and copolymers PE-co-M1, PE-co-M2, and PE-co-M3 were carried out and a throughout comparison was made. We have shown that electrochemical copolymerization is a powerful strategy to tune the highest occupied molecular orbital energy level, band gap, and color of the copolymer. Thus, this finding clearly indicates that the copolymers show significantly different optoelectronic properties compared to their constituent polymers.