Alkyne Monomers Research Articles

Cyclic polymers from alkynes: a review.

Cyclic polymers have applications across various fields, including material science, biomedicine, and inorganic chemistry. Cyclic polymers derived from alkyne monomers have expanded the application scope to include electronic materials and polyolefins. This review highlights recent advancements in the synthesis of cyclic polymers from both mono- and disubstituted alkynes. The aim is to provide a comprehensive overview of the synthetic methodologies and the application of cyclic polymers derived from alkynes. Additionally, this review will facilitate a comparative analysis of the advantages and limitations of various synthetic methods and describe opportunities for future development of novel catalytic systems to synthesize cyclic polymers from alkynes.

Thiol‐yne 3D Printable Polymeric Resins for the Efficient Removal of a Model Pollutant from Waters

AbstractA new 3D printable resin formulation is developed and optimized from commercially available thiol (pentaerythritol tetrakis(3‐mercaptopropionate); PETMP) and alkyne (3‐butyn‐1‐ol; BA) monomers. Printed objects are characterized by Fourier‐transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA). The extraction efficiency of the printed thiol‐yne device is then investigated using a model dye – malachite green (MG). The results displayed excellent dye removal efficiency with > 95% MG removed within 5 min. The 3D‐printed devices are reusable and show 100% removal over six cycles after washing with deionized water and methanol. The presence of surface hydroxyl groups derived from the BA monomer is shown to enhance dye adsorption in comparison to control materials. The printing procedure and resin formulation are robust and consistent when devices from different resin batches are compared for MG dye removal. The thiol‐yne 3D printed devices demonstrated excellent dye removal (> 99%) from water samples collected from a tap and a nearby river source. The successful development of this resin provides a new thiol‐yne‐based resin system for stereolithography (SLA) 3D printing for the removal of organic dyes from wastewater and presents a potential for broad applications in water treatment.

Relaxor ferroelectric polymer exhibits ultrahigh electromechanical coupling at low electric field.

Electromechanical (EM) coupling-the conversion of energy between electric and mechanical forms-in ferroelectrics has been used for a broad range of applications. Ferroelectric polymers have weak EM coupling that severely limits their usefulness for applications. We introduced a small amount of fluorinated alkyne (FA) monomers (<2 mol %) in relaxor ferroelectric poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) (PVDF-TrFE-CFE) terpolymer that markedly enhances the polarization change with strong EM coupling while suppressing other polarization changes that do not contribute to it. Under a low-dc bias field of 40 megavolts per meter, the relaxor tetrapolymer has an EM coupling factor (k33) of 88% and a piezoelectric coefficient (d33) >1000 picometers per volt. These values make this solution-processed polymer competitive with ceramic oxide piezoelectrics, with the potential for use in distinct applications.

Autonomous Visualization of Damage in Polymers by Metal-Free Polymerizations of Microencapsulated Activated Alkynes.

The development of autonomous materials with desired performance and built‐in visualizable sensing units is of great academic and industrial significance. Although a wide range of damage indication methods have been reported, the “turn‐on” sensing mechanism by damaging events based on microcapsule systems, especially those relying on chemical reactions to elicit a chromogenic response, are still very limited. Herein, a facile and metal‐free polymerization route with an interesting reaction‐induced coloration effect is demonstrated. Under the catalysis of 1,4‐diazabicyclo[2.2.2]octane (DABCO), the polymerizations of difunctional or trifunctional activated alkynes proceed very quickly at 0 °C in air. A series of polymers composed of stereoregular enyne structure (major unit) and divinyl ether structure (minor unit) are obtained. Both the catalyst and monomers are colorless while the polymerized products are deep‐colored. This process can be applied for the damage visualization of polymers using the microencapsulation technique. Microcapsules containing the reactive alkyne monomer are prepared and mixed in a DABCO‐dispersed polymer film. Both the external and internal damage regions of this composite film can be readily visualized once the reaction is initiated from the ruptured microcapsules. Moreover, the newly formed polymer automatically seals the cracks with an additional protection function.

Polytriazole resins toughened by an azide-terminated polyhedral oligomeric silsesquioxane (OADTP)

Abstract An azido-terminated polyhedral oligomeric silsesquioxane (POSS) compound, octakis(azidopropyl-3-oxycarbonyl-1-decyl-10-thiopropyl-3-)POSS (OADTP), is synthesized and characterized. POSS-polytriazole (PTA) resins are prepared from an azide, an alkyne monomer, and OADTP. The toughening effect of OADTP on PTA resins is analyzed by impact performance test and electronic microscope characterization, and the thermal performance of resins is measured by thermogravimetric analysis and dynamic mechanical analysis. The results show that the addition of the POSS can improve the mechanical properties of PTA resins. The impact strength of POSS-PTA resins first increases and then decreases with the increase in the POSS compound, and the maximum one arrives at 54.8 kJ m−2 which increases by 44.2% as compared to 38 kJ m−2 of the PTA resin. A good thermal stability remains in POSS-PTA resins.

High Refractive Index Photopolymers by Thiol-Yne "Click" Polymerization.

A scalable synthesis of high refractive index, optically transparent photopolymers from a family of low-viscosity multifunctional thiol and alkyne monomers via thiol-yne "click" is described herein. The monomers designed to incorporate high refractive index cores consisting of aryl and sulfide groups with high intrinsic molar refraction were synthesized starting from commercially available low-cost raw materials. The low-viscosity (<500 cP) thiol-yne resins formulated with these new multifunctional monomers and a phosphine oxide photoinitiator underwent efficient thiol-yne polymerizations upon exposure to 405 nm light at 30 mW/cm2. In contrast to the previously reported thiol-ene systems, the kinetic profile of these photopolymerizations showed significant dependence on the nature of the thiol and alkyne monomers. However, the ability of the thiol-yne reaction to introduce a large number of sulfide linkages compared to that of thiol-ene systems yielded cross-linked high optical quality photopolymers with a polymer refractive index that exceeds 1.68 (nD/20 °C). Interestingly, the photopolymer formed from the least sterically hindered alkynyl thioether monomer 2b with flexible thioether core and the dithiol 1a exhibited unprecedented difference in the polymer refractive index as compared to that of the resin with polymerization-induced changes reaching up to 0.08. Furthermore, the implementation of these low-viscosity thiol-yne resins was demonstrated by preparing two-stage photopolymeric holographic materials with a dynamic range of ∼0.02 and haze < 1.5% in two-dimensional high refractive index structures.

Effects of network structures on the tensile toughness of copper-catalyzed azide-alkyne cycloaddition (CuAAC)-based photopolymers.

In the present study, the photo-initiated copper-catalyzed azide-alkyne cycloaddition (CuAAC) polymerization was utilized to form structurally diverse glassy polymer networks. Systematic alterations in the monomer backbone rigidity (e.g., cyclic or aliphatic groups with a different length of backbone) and the reactive functional group density (e.g., tetra-, tri-, di-, and mono-functional azide and alkyne monomers) were used to provide readily tailorable network structures with crosslink densities (estimated from the rubbery modulus) varying by a factor of over 20. All eight of the resultant networks exhibited glass transition temperatures (Tg) between 50 and 80 °C with tensile toughness ranging from 28 to 61 MJ m-3. A nearly linear dependence of yield stress and elongation at break (broadly defined as strength and ductility, respectively) on the Tg and rubbery modulus was established in these triazole networks. When a flexible di-alkyne monomer (5 carbon spacing between alkynes) was incorporated in a network composed of a tri-alkyne and di-azide monomer, the elongation at break was improved from 166 to 300 %, while the yield stress was reduced from 36 to 23 MPa. Additionally, the polymer ductility was also varied by incorporating mono-functional azides as chain ends in the network - replacing a sterically hindered stiff mono-azide with a more flexible mono-azide increased the elongation at break from 24 to 185 % and the tensile toughness from 6 to 28 MJ m-3.

Direct growth of crystalline triazine-based graphdiyne using surface-assisted deprotection-polymerisation.

Graphdiyne polymers have interesting electronic properties due to their π-conjugated structure and modular composition. Most of the known synthetic pathways for graphdiyne polymers yield amorphous solids because the irreversible formation of carbon–carbon bonds proceeds under kinetic control and because of defects introduced by the inherent chemical lability of terminal alkyne bonds in the monomers. Here, we present a one-pot surface-assisted deprotection/polymerisation protocol for the synthesis of crystalline graphdiynes over a copper surface starting with stable trimethylsilylated alkyne monomers. In comparison to conventional polymerisation protocols, our method yields large-area crystalline thin graphdiyne films and, at the same time, minimises detrimental effects on the monomers like oxidation or cyclotrimerisation side reactions typically associated with terminal alkynes. A detailed study of the reaction mechanism reveals that the deprotection and polymerisation of the monomer is promoted by Cu(ii) oxide/hydroxide species on the as-received copper surface. These findings pave the way for the scalable synthesis of crystalline graphdiyne-based materials as cohesive thin films.

Metal-Free Catalysts for the Polymerization of Alkynyl-Based Monomers

Novel polymerizations based on alkyne monomers are becoming a powerful tool to construct polymers with unique structures and advanced functions in the areas of polymer and material sciences, and scientists have been attracted to develop a variety of novel polymerizations in recent decades. Therein, catalytic systems play an indispensable role in the influence of polymerization efficiencies and the performances of the resultant polymers. Concerning the shortcomings of metallic catalysts, much of the recent research focus has been on metal-free polymerization systems. In this paper, metal-free catalysts are classified and the corresponding polymerizations are reviewed, including organobase-catalyzed polymerizations, Lewis-acid-catalyzed polymerizations, as well as catalyst-free polymerizations. Moreover, the challenges and perspectives in this area are also briefly discussed.

Catalyst‐Free Four‐Component Polymerization of Propiolic Acids, Benzylamines, Organoboronic Acids, and Formaldehyde toward Functional Poly(propargylamine)s

Multicomponent polymerizations (MCPs) are a group of fascinating polymer synthesis approaches that are developed rapidly in the recent decade. As a popular alkyne-based MCP, the A3 -polycouplings of alkynes, aldehydes, and amines are developed for the synthesis of poly(propargylamine)s under the catalysis of metal catalysts. In this work, through the design of carboxylic acid group-activated alkyne monomers, a catalyst-free, four-component polymerization of propiolic acids, benzylamines, organoboronic acids, and formaldehyde is reported under mild condition at 45°C in dichloroethane. This four-component polymerization is applicable to different monomer structures, which can afford seven poly(propargylamine)s with up to 94% yields and molecular weights of up to 13 900gmol-1 . Moreover, the poly(propargylamine)s demonstrate good solubility and processibility, high thermal stability and light refractivity, unique photophysical property, and so on. The simple monomers, mild condition, low cost, high efficiency, and procedure simplicity of this catalyst-free four-component polymerization demonstrates an elegant example of functional polymer synthesis.

Cobalt-catalyzed [2 + 2 + 2] cycloaddition copolymerization of diyne and internal alkyne monomers to highly branched polymers

A novel synthetic method for hyperbranched polymers is reported. A cobalt catalyst previously developed in our group promotes the catalytic alkyne [2 + 2 + 2] cycloaddition polymerization of aromatic diynes with internal alkynes, which proceeds without gelation or production of insoluble materials to give the corresponding soluble polymer in good yields. The method is reproducible, and the polymerization behavior can readily be predicted by the results of model reactions. Thus, the molecular weight and a degree of branching (DB) of the resulting polymer can be controlled by selecting the internal alkyne monomer and its loading amount. The occurrence of effective endcapping reaction was confirmed by degradation of the polymer derived from a diyne bearing a silyl ether linker, and a high DB of more than 0.5 was obtained.

Synthesis of a two‐dimensional porphyrin framework connected by 1,3‐diyne linkages via in situ deprotection of trimethylsilicon at a water/oil interface

AbstractDeveloping two‐dimensional (2D) porphyrin frameworks is a hot topic in the research of 2D materials. Glaser reaction between terminal alkyne monomers at an interface is promising for creating 2D polymers, such as graphdiyne. However, the coupling reaction between terminal alkyne–porphyrin monomers is impossible due to insolubility in low‐polarity solvents. Herein we used a trimethylsilicon (TMS)‐protected precursor as monomer directly and the above problem was solved by in situ deprotection of TMS at a water/toluene interface. The obtained 2D porphyrin framework connected by 1,3‐diyne linkages exhibits nanometer thickness and can be free‐standing under ambient conditions. This method not only reduces the workload of monomer synthesis, but also overcomes the limitation of Glaser reaction for producing 2D polymer films at an interface when the terminal alkyne monomer is insoluble in nonpolar solvents. © 2020 Society of Industrial Chemistry

Synthesis of Functional Hyperbranched Poly(methyltriazolylcarboxylate)s by Catalyst-free Click Polymerization of Butynoates and Azides

Azide-alkyne click polymerization has become a powerful tool for polymer synthesis. However, the click polymerization between internal alkynes and azides is rarely utilized to prepare functional polymers. In this work, the polymerization reactions of activated internal alkyne monomers of tris(2-butynoate)s (1) with tetraphenylethene-containing diazides (2) were performed in dimethylformamide (DMF) under simple heating, affording four hyperbranched poly(methyltriazolylcarboxylate)s (hb-PMTCs) with high molecular weights (Mw up to 2.4 × 104) and regioregularities (up to 83.9%) in good yields. The hb-PMTCs are soluble in common organic solvents, and thermally stable with 5% weight loss temperatures up to 400 °C. They are non-emissive in dilute solution, but become highly emissive in aggregated state, exhibiting aggregation-induced emission characteristics. The polymers can generate fluorescent photopatterns with high resolution, and can work as fluorescent sensors to detect nitroaromatic explosive with high sensitivity.

High impact polytriazole resins for advanced composites

ABSTRACT Three azido-terminated poly(ethylene glycol) macromonomers (ATPEGs) were synthesized from poly(ethylene glycol)s (PEGs) and characterized. The extended polytriazole (EPTA) resins were prepared from the macromonomers, azide and alkyne monomers. Toughening effect of PEGs on polytriazole resins was analyzed by means of mechanical, thermal and electronic microscope characterization. The results show that molecular weight and content of ATPEGs have great influence on the thermal and mechanical properties of cured EPTA resins. The impact strength of cured EPTA resins increases with the increase of the amount and molecular weight of ATPEGs. The flexural strength and heat resistance of cured EPTA resins decrease with the increase of addition amount and molecular weight of ATPEGs. High impact EPTA resins were obtained.

Photoinitiated Copper(I) Catalyzed Azide-Alkyne Cycloaddition Reaction for Ion Conductive Networks.

The photoinitiated copper(I) catalyzed azide-alkyne cycloaddition (photo-CuAAC) is a 'click' reaction that enables spatially and temporally controlled polymerizations. The solvent-less photopolymerization of multi-functional azide and cationic alkyne monomers results in the rapid formation of a charged polymer network. Full conversion of these monomers is achieved within 30 minutes under mild, blue-light irradiation conditions (470 nm light at 30 mW/cm2). The modulus of the material is readily tuned by controlling the ratio of di- and tri-functional alkyne monomers. Facile exchange of the hydrophobic bistriflimide counterion for a hydroxide anion yields an ion conductive polymer network with photopatternable charged regions. The spatiotemporal nature of the ionic photo-CuAAC reaction coupled with the chemical stability and mechanical flexibility suggests this chemistry is a facile and novel approach for ion-containing material synthesis (e.g., alkaline fuel cells components).

Thiol–yne chemistry for 3D printing: exploiting an off-stoichiometric route for selective functionalization of 3D objects

An alkyne monomer, bis(propargyl) fumarate, is synthesized and mixed to a thiol monomer to produce DLP-3D printable formulations. Using off-stoichiometric formulations it is possible to print functionalizable objects.

Exploring Network Formation of Tough and Biocompatible Thiol‐yne Based Photopolymers

This work deals with the in-depth investigation of thiol-yne based network formation and its effect on thermomechanical properties and impact strength. The results show that the bifunctional alkyne monomer di(but-1-yne-4-yl)carbonate (DBC) provides significantly lower cytotoxicity than the comparable acrylate, 1,4-butanediol diacrylate (BDA). Real-time near infrared photorheology measurements reveal that gel formation is shifted to higher conversions for DBC/thiol resins leading to lower shrinkage stress and higher overall monomer conversion than BDA. Glass transition temperature (Tg ), shrinkage stress, as well as network density determined by double quantum solid state NMR, increase proportionally with the thiol functionality. Most importantly, highly cross-linked DBC/dipentaerythritol hexa(3-mercaptopropionate) networks (Tg ≈ 61 °C) provide a 5.3 times higher impact strength than BDA, which is explained by the unique network homogeneity of thiol-yne photopolymers.

Click Chemistry Immobilization of Antibodies on Polymer Coated Gold Nanoparticles.

The goal of this work is to develop an innovative approach for the coating of gold nanoparticles (AuNPs) with a synthetic functional copolymer. This stable coating with a thickness of few nanometers provides, at the same time, stabilization and functionalization of the particles. The polymeric coating consists of a backbone of polydimethylacrylamide (DMA) functionalized with an alkyne monomer that allows the binding of azido modified molecules by Cu(I)-catalyzed azide/alkyne 1,3-dipolar cycloaddition (CuAAC, click chemistry). The thin polymer layer on the surface stabilizes the colloidal suspension whereas the alkyne functions pending from the backbone are available for the reaction with azido-modified proteins. The reactivity of the coating is demonstrated by immobilizing an azido modified anti-mouse IgG antibody on the particle surface. This approach for the covalent binding of antibody to a gold-NPs is applied to the development of gold labels in biosensing techniques.

Cyclic polymers from alkynes.

Cyclic polymers have dramatically different physical properties compared with those of their equivalent linear counterparts. However, the exploration of cyclic polymers is limited because of the inherent challenges associated with their synthesis. Conjugated linear polyacetylenes are important materials for electrical conductivity, paramagnetic susceptibility, optical nonlinearity, photoconductivity, gas permeability, liquid crystallinity and chain helicity. However, their cyclic analogues are unknown, and therefore the ability to examine how a cyclic topology influences their properties is currently not possible. We have solved this challenge and now report a tungsten catalyst supported by a tetraanionic pincer ligand that can rapidly polymerize alkynes to form conjugated macrocycles in high yield. The catalyst works by tethering the ends of the polymer to the metal centre to overcome the inherent entropic penalty of cyclization. Gel-permeation chromatography, dynamic and static light scattering, viscometry and chemical tests are all consistent with theoretical predictions and provide unambiguous confirmation of a cyclic topology. Access to a wide variety of new cyclic polymers is now possible by simply choosing the appropriate alkyne monomer.

Clickable Polymeric Coating for Oriented Peptide Immobilization.

A new methodology for the fabrication of an high-performance peptide microarray is reported, combining the higher sensitivity of a layered Si-SiO2 substrate with the oriented immobilization of peptides using a N,N-dimethylacrylamide-based polymeric coating that contains alkyne monomers as functional groups. This clickable polymer allows the oriented attachment of azido-modified peptides via a copper-mediated azide/alkyne cycloaddition. A similar coating that does not contain the alkyne functionality has been used as comparison, to demonstrate the importance of a proper orientation for facilitating the probe recognition and interaction with the target antibody.