Journal articles: 'Alkynes Thermal properties'

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Michinobu, Tsuyoshi. "Click synthesis of donor–acceptor-type aromatic polymers." Pure and Applied Chemistry 82, no. 4 (March 13, 2010): 1001–9. http://dx.doi.org/10.1351/pac-con-09-09-09.

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A high-yielding addition reaction between electron-rich alkynes and a small acceptor molecule, tetracyanoethylene (TCNE), was employed as a new click reaction to construct donor–acceptor chromophores in the polymer main chains and side chains. The donor–acceptor alternating conjugated polymers were prepared from the ferrocene-containing poly(aryleneethynylene)s in one step and atom-economic fashion. The energy levels and thermal properties of the aromatic polyamines substituted by electron-rich alkynes as a side chain can be tunable by the amount of the added TCNE. The resulting donor–acceptor-type polymers feature broad charge-transfer (CT) bands in the visible region, potent redox activities, and improved thermal properties.

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Cervera-Procas, Ramón, José-Luis Serrano, and Ana Omenat. "A Highly Versatile Polymer Network Based on Liquid Crystalline Dendrimers." International Journal of Molecular Sciences 22, no. 11 (May 27, 2021): 5740. http://dx.doi.org/10.3390/ijms22115740.

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Highly functional macromolecules with a well-defined architecture are the key to designing efficient and smart materials, and these polymeric systems can be tailored for specific applications in a diverse range of fields. Herein, the formation of a new liquid crystalline polymeric network based on the crosslinking of dendrimeric entities by the CuI-catalyzed variant of the Huisgen 1,3-dipolar cycloaddition of azides and alkynes to afford 1,2,3-triazoles is reported. The polymeric material obtained in this way is easy to process and exhibits a variety of properties, which include mesomorphism, viscoelastic behavior, and thermal contraction. The porous microstructure of the polymer network determines its capability to absorb solvent molecules and to encapsulate small molecules, like organic dyes, which can be released easily afterwards. Moreover, all these properties may be easily tuned by modifying the chemical structure of the constituent dendrimers, which makes this system a very interesting one for a number of applications.

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Hernández-Fernández, Joaquín, John R. Castro-Suarez, and Carlos A. T. Toloza. "Iron Oxide Powder as Responsible for the Generation of Industrial Polypropylene Waste and as a Co-Catalyst for the Pyrolysis of Non-Additive Resins." International Journal of Molecular Sciences 23, no. 19 (October 3, 2022): 11708. http://dx.doi.org/10.3390/ijms231911708.

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For the synthesis of polymeric resins, it is of great importance to review the raw materials and the equipment to be used to avoid the presence of compounds that may affect the effectiveness of the polymerization and the characteristics of the plastic to be obtained. Iron oxide is a compound that can be present in reactors after maintenance due to the techniques used and the cleaning of this equipment, and it can affect the characteristics of the resins, reducing their quality. In this study, the presence of FeO in different concentrations was evaluated to determine its effects on the properties and pyrolysis of polypropylene resins by using X-ray refraction to determine the elements of the samples, evaluating thermal degradation by TGA, the variation in molecular weight by measuring the MFI, and the compounds obtained from pyrolysis by chromatography. The results showed that the thermal degradation decreased as the FeO concentration increased, while for the MFI, the relationship was directly proportional. The evaluation of the compounds obtained from pyrolysis showed an increase in the production of alcohols, alkynes, ketones, and acids, and a decrease in alkanes and alkenes, showing that FeO affects the properties of polypropylene and the compounds that are produced during pyrolysis.

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Schumann, Hans, Gert Admiraal, and Paul T. Beurskens. "Zum Koordinationsverhalten von Alkinen gegenüber dem [C5H5(P(OCH3)3)2Fe]+-Fragment: Bildung und Struktur carbonylfreier Halbsandwichkomplexe mit Alkin- und Vinylidenliganden / Coordination Properties of Alkynes towards the [C5H5Fe(P(OCH3)3)2]+ Fragment: Formation and Structure of Carbonylfree Halfsandwich Complexes with Alkyne and Vinylidene Ligands." Zeitschrift für Naturforschung B 47, no. 8 (August 1, 1992): 1125–33. http://dx.doi.org/10.1515/znb-1992-0813.

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The alkyne containing halfsandwich complexes [C5H5(P(OCH3)3)2Fe(HC ≡ CC6H5)]PF6 (IIIa) and [C5H5(P(OCH3)3)2Fe(CH3O2CC = CCO2CH3)]PF6 (IIIb) are accessible by thermal acetonitrile substitution from [C5H5(P(OCH3)3)2Fe(NCCH3)]PF6 (I) in the presence of the alkyne. Upon standing in solution, IIIa isomerizes to give the isomeric phenylvinylidene complex [C5H5(P(OCH3)3)2Fe(C=C(C6H5)H)]PF6 (IV). The spectroscopic data are presented together with a discussion of the X-ray structure determinations of IIIb and IV.

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Schock, Marvin, and Stefan Bräse. "Reactive & Efficient: Organic Azides as Cross-Linkers in Material Sciences." Molecules 25, no. 4 (February 24, 2020): 1009. http://dx.doi.org/10.3390/molecules25041009.

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The exceptional reactivity of the azide group makes organic azides a highly versatile family of compounds in chemistry and the material sciences. One of the most prominent reactions employing organic azides is the regioselective copper(I)-catalyzed Huisgen 1,3-dipolar cycloaddition with alkynes yielding 1,2,3-triazoles. Other named reactions include the Staudinger reduction, the aza-Wittig reaction, and the Curtius rearrangement. The popularity of organic azides in material sciences is mostly based on their propensity to release nitrogen by thermal activation or photolysis. On the one hand, this scission reaction is accompanied with a considerable output of energy, making them interesting as highly energetic materials. On the other hand, it produces highly reactive nitrenes that show extraordinary efficiency in polymer crosslinking, a process used to alter the physical properties of polymers and to boost efficiencies of polymer-based devices such as membrane fuel cells, organic solar cells (OSCs), light-emitting diodes (LEDs), and organic field-effect transistors (OFETs). Thermosets are also suitable application areas. In most cases, organic azides with multiple azide functions are employed which can either be small molecules or oligo- and polymers. This review focuses on nitrene-based applications of multivalent organic azides in the material and life sciences.

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Jiang, Wenzhao, Hangbo Yue, Peter Shuttleworth, Pengbo Xie, Shanji Li, and Jianwei Guo. "Adamantane-Based Micro- and Ultra-Microporous Frameworks for Efficient Small Gas and Toxic Organic Vapor Adsorption." Polymers 11, no. 3 (March 13, 2019): 486. http://dx.doi.org/10.3390/polym11030486.

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Microporous organic polymers and related porous materials have been applied in a wide range of practical applications such as adsorption, catalysis, adsorption, and sensing fields. However, some limitations, like wide pore size distribution, may limit their further applications, especially for adsorption. Here, micro- and ultra-microporous frameworks (HBPBA-D and TBBPA-D) were designed and synthesized via Sonogashira–Hagihara coupling of six/eight-arm bromophenyl adamantane-based “knots” and alkynes-type “rod” monomers. The BET surface area and pore size distribution of these frameworks were in the region of 395–488 m2 g−1, 0.9–1.1 and 0.42 nm, respectively. The as-made prepared frameworks also showed good chemical ability and high thermal stability up to 350 °C, and at 800 °C only 30% mass loss was observed. Their adsorption capacities for small gas molecules such as CO2 and CH4 was 8.9–9.0 wt % and 1.43–1.63 wt % at 273 K/1 bar, and for the toxic organic vapors n-hexane and benzene, 104–172 mg g−1 and 144–272 mg g−1 at 298 K/0.8 bar, respectively. These are comparable to many porous polymers with higher BET specific surface areas or after functionalization. These properties make the resulting frameworks efficient absorbent alternatives for small gas or toxic vapor capture, especially in harsh environments.

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Raytchev, Pascal Dimitrov, Céline Besset, Etienne Fleury, Jean-Pierre Pascault, Julien Bernard, and Eric Drockenmuller. "1,4:3,6-Dianhydrohexitols: Original platform for the design of biobased polymers using robust, efficient, and orthogonal chemistry." Pure and Applied Chemistry 85, no. 3 (August 15, 2012): 511–20. http://dx.doi.org/10.1351/pac-con-12-03-11.

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1,4:3,6-Dianhydrohexitols (DAHs) are nontoxic and sustainable diols that have been extensively applied as monomers for the preparation of polymer materials by step-growth polymerization processes. The presence of two reactive alcohol groups was exploited to design a library of symmetric and asymmetric stereocontrolled alkyne- and/or azide-functionalized AA/BB and AB monomers suitable for thermal or copper(I)-catalyzed azide-alkyne cycloaddition (TAAC and CuAAC). Step-growth polymerization of these monomers yielded a series of linear polytriazoles as well as partially biosourced networks using a combination of AB + A2B2 derivatives. Characterization of the resulting materials allowed for the establishment of a thorough structure–property relationship emphasizing the impact of monomer stereochemistry and cycloaddition regioselectivity on materials properties.

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Liu, Yu, Hai-Ying Wang, Gang Chen, Xiao-Ping Xu, and Shun-Jun Ji. "Synthesis and Properties of Novel 'Ethyne-linked' Compounds Containing Carbazole and 1, 8-naphthalimide Groups." Australian Journal of Chemistry 62, no. 8 (2009): 934. http://dx.doi.org/10.1071/ch08411.

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A series of the novel ‘ethyne-linked’ compounds containing carbazole and 1,8-naphthalimide groups have been synthesized by Pd/Cu-catalyzed Sonogashira reaction. These compounds were fully characterized by means of Fourier-transform IR, 1H, 13C NMR, and high resolution mass spectroscopy. The thermal, optical, and electrochemical properties were also investigated. As we expected, the results indicated that these compounds could improve charge-transport ability and fluorescent quantum yield by introducing the electron-transporting emitting moieties naphthalimide and the alkyne group to carbazole moieties.

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9

Hu, Yingxue, Joshua B. Marlow, Rajesh Ramanathan, Wenyue Zou, Hui Geok Tiew, Matthew J. Pottage, Vipul Bansal, Rico F. Tabor, and Brendan L. Wilkinson. "Synthesis and Properties of Photoswitchable Carbohydrate Fluorosurfactants." Australian Journal of Chemistry 68, no. 12 (2015): 1880. http://dx.doi.org/10.1071/ch15434.

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We describe the parallel synthesis, photocontrollable surface tension, and antibacterial performance of a new class of carbohydrate fluorosurfactant. Novel fluorosurfactants comprised a mono- or disaccharide head group linked to an azobenzene unit that was variably substituted with a trifluoromethyl group. Fluorosurfactants were rapidly assembled using the venerable CuI-catalysed azide–alkyne cycloaddition reaction and exhibited light-addressable surface activity, excellent water solubility, and selective antibacterial activity against Gram-positive Staphylococcus aureus. Notably, the physicochemical and biological activity of these novel materials was heavily dependent on the nature of the head group and the position of the trifluoromethyl substituent on the azobenzene ring. The UV-adapted cis-isomer of fluorosurfactants displayed good thermal stability at ambient temperature, with little reversion to the stable trans isomer after 16 h. These novel, light-responsive materials should find broad interest in a range of biomedical and technological fields, including drug and gene delivery, self-cleaning oleophobic surfaces, and antibacterial coatings for medical devices.

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Yu, Wen Hao, Yue Feng Bai, Yang Jing, Shi Chang Nie, Bi Qin Wang, Ping Hu, and Ke Qing Zhao. "Synthesis of Disk-Rod-Disk Liquid Crystal Trimers by Using Click Chemistry." Key Engineering Materials 428-429 (January 2010): 106–10. http://dx.doi.org/10.4028/www.scientific.net/kem.428-429.106.

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A series of disk-rod-disk liquid crystal trimers have been synthesized. Two triphenylene discogens have been connected to a biphenyl mesogen via CuI-NEt3 catalyzed alkyne azide cycloaddition in toluene at room temperature. The trimers have been characterized by using 1H NMR, IR, high resolution Mass spectra and the mesomorphic properties investigated with polarized optical microscopy (POM), differential scanning calorimetry (DSC), and X-ray diffraction. The result shows that the trimers exhibited rectangular columnar mesophase (Colr). The length of the flexible spacer connecting the three segments has important influence on the thermal behaviors of the trimers.

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11

Yu, Zhuoer, Jun Zhang, Bangqiang Wu, Liqiang Wan, and Farong Huang. "Polytriazole resins toughened by an azide-terminated polyhedral oligomeric silsesquioxane (OADTP)." e-Polymers 21, no. 1 (January 1, 2021): 289–98. http://dx.doi.org/10.1515/epoly-2021-0033.

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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.

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12

Acar, Işıl, Ayça Bal, and Gamze Güçlü. "The use of intermediates obtained from aminoglycolysis of waste poly(ethylene terephthalate) (PET) for the synthesis of water-reducible alkyd resin." Canadian Journal of Chemistry 91, no. 5 (May 2013): 357–63. http://dx.doi.org/10.1139/cjc-2012-0370.

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In this study, depolymerization products obtained from an aminoglycolysis reaction of postconsumer poly(ethylene terephthalate) (PET) bottles were used for the synthesis of water-reducible alkyd resins for the first time. We also aimed to reduce the amount of amine using aminoglycolysis products of PET having amine end groups for the neutralization of alkyds in this work. Alkyds formulated to have an oil content of 50% were prepared with glycerine (G), ethylene glycol (EG), fatty acid (FA), and phthalic anhydride (PA) or aminoglycolysis depolymerization products (ADP). The “K alkyd constant system” was used for the formulation calculations of the alkyd resins. The K constant was 1.1 and the ratio of basic equivalents to acid equivalents (R) was 1.15. Physical and chemical film properties and thermal degradation stabilities of these alkyd resins were investigated. According to the results of surface coating tests, the properties of the waste PET-based alkyd resins were found to be compatible with the properties of the reference resins. In addition, thermal degradation stabilities of the water-reducible alkyd resins prepared by ADP were better than that of the reference resin. As a result, we concluded that aminoglycolysis products of waste PET are suitable for manufacturing water-reducible alkyd resins. Furthermore, the amount of amine used for the neutralization stage of preparing water-reducible resin was reduced by 50% using aminoglycolysis products having an amine end group.

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13

Floros, Michael C., Alcides Lopes Leão, and Suresh S. Narine. "Vegetable Oil Derived Solvent, and Catalyst Free “Click Chemistry” Thermoplastic Polytriazoles." BioMed Research International 2014 (2014): 1–14. http://dx.doi.org/10.1155/2014/792901.

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Azide-alkyne Huisgen “click” chemistry provides new synthetic routes for making thermoplastic polytriazole polymers—without solvent or catalyst. This method was used to polymerize three diester dialkyne monomers with a lipid derived 18 carbon diazide to produce a series of polymers (labelled C18C18, C18C9, and C18C4 based on monomer chain lengths) free of residual solvent and catalyst. Three diester dialkyne monomers were synthesized with ester chain lengths of 4, 9, and 18 carbons from renewable sources. Significant differences in thermal and mechanical properties were observed between C18C9 and the two other polymers. C18C9 presented a lower melting temperature, higher elongation at break, and reduced Young’s modulus compared to C18C4 and C18C18. This was due to the “odd-even” effect induced by the number of carbon atoms in the monomers which resulted in orientation of the ester linkages of C18C9 in the same direction, thereby reducing hydrogen bonding. The thermoplastic polytriazoles presented are novel polymers derived from vegetable oil with favourable mechanical and thermal properties suitable for a large range of applications where no residual solvent or catalyst can be tolerated. Their added potential biocompatibility and biodegradability make them ideal for applications in the medical and pharmaceutical industries.

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Kashina, Anna V., Tamara K. Meleshko, Natalia N. Bogorad, Viktor K. Lavrentyev, and Alexander V. Yakimansky. "Molecular Brushes with a Polyimide Backbone and Poly(ε-Caprolactone) Side Chains by the Combination of ATRP, ROP, and CuAAC." Polymers 13, no. 19 (September 28, 2021): 3312. http://dx.doi.org/10.3390/polym13193312.

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An approach to the synthesis of the novel molecular brushes with a polyimide (PI) backbone and poly(ε-caprolactone) (PCL) side chains was developed. To obtain such copolymers, a combination of various synthesis methods was used, including polycondensation, atom transfer radical polymerization (ATRP), ring opening polymerization (ROP), and Cu (I)-catalyzed azide-alkyne Huisgen cycloaddition (CuAAC). ATRP of 2-hydroxyethyl methacrylate (HEMA) on PI macroinitiator followed by ROP of ε-caprolactone (CL) provided a “brush on brush” structure PI-g-(PHEMA-g-PCL). For the synthesis of PI-g-PCL two synthetic routes combining ROP and CuAAC were compared: (1) polymer-analogous transformations of a multicenter PI macroinitiator with an initiating hydroxyl group separated from the main chain by a triazole ring followed by ROP of CL, or (2) a separate synthesis of macromonomers with the desirable functional groups (polyimide with azide groups and PCL with terminal alkyne groups), followed by a click reaction. Results showed that the first approach allows to obtain graft copolymers with a PI backbone and relatively short PCL side chains. While the implementation of the second approach leads to a more significant increase in the molecular weight, but unreacted linear PCL remains in the system. Obtained macroinitiators and copolymers were characterized using 1H NMR and IR spectroscopy, their molecular weight characteristics were determined by SEC with triple detection. TGA and DSC were used to determine their thermal properties. X-ray scattering data showed that the introduction of a polyimide block into the polycaprolactone matrix did not change the degree of crystallinity of PCL.

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Legzdins, Peter, Kevin M. Smith, and Steven J. Rettig. "Synthesis, characterization, and properties of some cyclopentadienyl molybdenum nitrosyl benzyl complexes." Canadian Journal of Chemistry 79, no. 5-6 (May 1, 2001): 502–9. http://dx.doi.org/10.1139/v00-158.

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Reaction of CpMo(NO)(CH2Ph)Cl with Me2Mg, Ph2Mg, or PhCCLi reagents in THF affords the corresponding alkyl, aryl, or alkynyl CpMo(NO)(CH2Ph)R (R = hydrocarbyl) complexes as orange powders in good yields. Unlike related 16-electron CpMo(NO)R2 complexes, these 18-electron species exhibit good thermal stability due to their η2-benzyl-Mo interactions. Treatment of CpMo(NO)(CH2Ph)Cl with Na(DME)Cp provides dark green Cp2Mo(NO)(CH2Ph), whose solid-state molecular structure has been established by a single-crystal X-ray crystallographic analysis. The two Cp rings display different binding modes to the Mo atom, while the benzyl ligand is coordinated to the metal centre in an η1 fashion. The triflate complex, CpMo(NO)(CH2Ph)(OTf), is obtained by addition of AgOTf to the benzyl chloride precursor. The covalent MoOTf bond in this compound can be disrupted by the addition of Lewis bases (L) such as PPh3 or pyridine, leading to the corresponding [CpMo(NO)(CH2Ph)(L)][OTf] salts. Attempts to generate neutral benzylidene complexes by deprotonation of [CpMo(NO)(CH2Ph)(PPh3)][OTf] have not yet been successful.Key words: nitrosyl, molybdenum, benzyl, hydrocarbyl, triflate.

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16

Tomczyk, Mateusz D., Mariusz Zalewski, Per T. Jørgensen, Jesper Wengel, and Krzysztof Walczak. "Polyamine–Oligonucleotide Conjugates: 2′-OMe-Triazole-Linked 1,4,7,10-Tetraazacyclododecane and Intercalating Dyes and Their Effect on the Thermal Stability of DNA Duplexes." Pharmaceutics 14, no. 1 (December 28, 2021): 66. http://dx.doi.org/10.3390/pharmaceutics14010066.

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Oligonucleotides with the sequences 5′-GTG AUPA TGC, 5′-GCA TAUP CAC and 5′-GUPG ATA UPGC, where UP is 2′-O-propargyl uridine, were subjected to post-synthetic Cu(I)-catalyzed azide–alkyne cycloaddition to attach 1,4,7,10-tetraazacyclododecane (cyclen) and two well-known DNA intercalating dyes: thioxanthone and 1,8-naphthalimide. We propose a convenient cyclen protection–deprotection strategy that allows efficient separation of the resulting polyamine–oligonucleotide conjugates from the starting materials by RP-HPLC to obtain high-purity products. In this paper, we present hitherto unknown macrocyclic polyamine–oligonucleotide conjugates and their hybridization properties reflected in the thermal stability of thirty-two DNA duplexes containing combinations of labeled strands, their unmodified complementary strands, and strands with single base pair mismatches. Circular dichroism measurements showed that the B-conformation is retained for all dsDNAs consisting of unmodified and modified oligonucleotides. An additive and destabilizing effect of cyclen moieties attached to dsDNAs was observed. Tm measurements indicate that placing the hydrophobic dye opposite to the cyclen moiety can reduce its destabilizing effect and increase the thermal stability of the duplex. Interestingly, the cyclen-modified U showed significant selectivity for TT mismatch, which resulted in stabilization of the duplex. We conclude the paper with a brief review and discussion in which we compare our results with several examples of oligonucleotides labeled with polyamines at internal strand positions known in the literature.

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T. de Carvalho, Layde, Maria Luiza da S. Paula, Rodolfo M. de Moraes, Gizelda M. Alves, Talita M. Lacerda, Julio C. dos Santos, Amilton M. dos Santos, and Simone de F. Medeiros. "Chemical Modification of Pullulan Exopolysaccharide by Grafting Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBHV) via Click Chemistry." Polymers 12, no. 11 (October 29, 2020): 2527. http://dx.doi.org/10.3390/polym12112527.

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Biodegradable and biocompatible copolymers have been often studied for the development of biomaterials for drug delivery systems. In this context, this work reports the synthesis and characterization of a novel pullulan-g-poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (Pull-g-PHBHV) graft copolymer using click chemistry. Well-defined and functional pullulan backbones containing azide groups (PullN3) previously prepared by our group were successfully used for this purpose and propargyl-terminated poly(3-hydroxybutyrate-co-3-hydroxyvalerate) was prepared via transesterification using propargyl alcohol as a chain transfer agent. By an alkyne-azide cycloaddition reaction catalyzed by copper (Cu (I)) (CuAAC), the graft copolymer Pull-g-PHBHV was obtained. The chemical structures of the polymers were accessed by 1H NMR and 13C NMR FTIR. Disappearance of the bands referring to the main bonds evidenced success in the grafting reaction. Besides that, DRX, DSC and TGA were used in order to access the changes in crystallinity and thermal behavior of the material. The remaining crystallinity of the Pull-g-PHBHV structure evidences the presence of PHBHV. Pull-g-PHBHV presented lower degradation maximum temperature values than the starting materials, indicating its minor thermal stability. Finally, the synthesized material is an innovative biopolymer, which has never been reported in the previous literature. It is a bio-derived and biodegradable polymer, chemically modified, resulting in interesting properties which can be useful for their further applications as biomedical systems for controlled delivery, for example.

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Trejo-Maldonado, Melisa, Aisha Womiloju, Steffi Stumpf, Stephanie Hoeppener, Ulrich S. Schubert, Luis E. Elizalde, and Carlos Guerrero-Sanchez. "Triazole-Functionalized Mesoporous Materials Based on Poly(styrene-block-lactic acid): A Morphology Study of Thin Films." Polymers 14, no. 11 (May 31, 2022): 2231. http://dx.doi.org/10.3390/polym14112231.

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We report the synthesis of poly(styrene-block-lactic acid) (PS-b-PLA) copolymers with triazole rings as a junction between blocks. These materials were prepared via a ‘click’ strategy which involved the reaction between azide-terminated poly(styrene) (PS-N3) and acetylene-terminated poly(D,L-lactic acid) (PLA-Ac), accomplished by copper-catalyzed azide-alkyne cycloaddition reaction. This synthetic approach has demonstrated to be effective to obtain specific copolymer structures with targeted self-assembly properties. We observed the self-assembly behavior of the PS-b-PLA thin films as induced by solvent vapor annealing (SVA), thermal annealing (TA), and hydrolysis of the as-spun substrates and monitored their morphological changes by means of different microscopic techniques. Self-assembly via SVA and TA proved to be strongly dependent on the pretreatment of the substrates. Microphase segregation of the untreated films yielded a pore size of 125 nm after a 45-min SVA. After selectively removing the PLA microdomains, the as-spun substrates exhibited the formation of pores on the surface, which can be a good alternative to form an ordered pattern of triazole functionalized porous PS at the mesoscale. Finally, as revealed by scanning electron microscopy–energy dispersive X-ray spectroscopy, the obtained triazole-functionalized PS-porous film exhibited some affinity to copper (Cu) in solution. These materials are suitable candidates to further study its metal-caption properties.

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Ulloa, José Antonio, Joaquín Barberá, and José Luis Serrano. "Gold Nanoparticles Modification with Liquid Crystalline Polybenzylic Dendrons via 1,3-Dipolar Cycloaddition." Nanomaterials 12, no. 22 (November 16, 2022): 4026. http://dx.doi.org/10.3390/nano12224026.

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A series of six polybenzylic dendrons with an alkynyl focal point were synthesized for their incorporation to gold nanoparticles. Five of these compounds showed columnar mesomorphism in a wide range of temperatures. These dendrons were reacted with gold nanoparticles stabilized with a combination of a dodecanethiol and 11-azidoundecane-1-thiol. The azido group of the last compound allowed the functionalization of the nanoparticles with the six polybenzylic dendrons by 1,3-dipolar cycloaddition between their alkynyl groups and the terminal azido groups of the thiols. A high efficiency of the cycloaddition process (47–69%) was confirmed by several experimental techniques and no decomposition or aggregation phenomena were detected in the dendron-coated nanoparticles. The involved mechanism and the resulting percentage composition of the final materials are discussed. The results of the ulterior growth of the nanoparticles by thermal treatment are influenced by the size and the shape of the dendron and the temperature of the process. The structures of the final nanoparticles were investigated by TEM, DSC, TGA, NMR and UV-Vis spectroscopy. These nanoparticles do not show liquid crystal properties. However, a melting process between a crystalline and a fluid phase is observed. In the solid phase, the nanomaterials prepared show a short-range interaction between nanoparticles with a 2D local hexagonal order. A near-field effect was observed in the UV-vis spectra by coupling of different surface plasmon resonance bands (SPR) probably due to the short-range interactions. The main novelty of this work lies in the scarcity of previous studies of gold nanoparticles coated with dendrons forming themselves columnar mesophases. Most of the studies reported in the literature deal with gold nanoparticles coated with calamitic mesogens. Additionally, the effect of the thermal treatment, which in a previous paper was shown to increase the mean size of the nanoparticles without increasing their size polydispersity, has been studied in these materials.

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Riccardi, Claudia, Albert Meyer, Jean-Jacques Vasseur, Domenico Cavasso, Irene Russo Krauss, Luigi Paduano, François Morvan, and Daniela Montesarchio. "Design, Synthesis and Characterization of Cyclic NU172 Analogues: A Biophysical and Biological Insight." International Journal of Molecular Sciences 21, no. 11 (May 29, 2020): 3860. http://dx.doi.org/10.3390/ijms21113860.

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NU172—a 26-mer oligonucleotide able to bind exosite I of human thrombin and inhibit its activity—was the first aptamer to reach Phase II clinical studies as an anticoagulant in heart disease treatments. With the aim of favoring its functional duplex-quadruplex conformation and thus improving its enzymatic stability, as well as its thrombin inhibitory activity, herein a focused set of cyclic NU172 analogues—obtained by connecting its 5′- and 3′-extremities with flexible linkers—was synthesized. Two different chemical approaches were exploited in the cyclization procedure, one based on the oxime ligation method and the other on Cu(I)-assisted azide-alkyne cycloaddition (CuAAC), affording NU172 analogues including circularizing linkers with different length and chemical nature. The resulting cyclic NU172 derivatives were characterized using several biophysical techniques (ultraviolet (UV) and circular dichroism (CD) spectroscopies, gel electrophoresis) and then investigated for their serum resistance and anticoagulant activity in vitro. All the cyclic NU172 analogues showed higher thermal stability and nuclease resistance compared to unmodified NU172. These favorable properties were, however, associated with reduced—even though still significant—anticoagulant activity, suggesting that the conformational constraints introduced upon cyclization were somehow detrimental for protein recognition. These results provide useful information for the design of improved analogues of NU172 and related duplex-quadruplex structures.

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Nielsen, Mogens Brøndsted, Søren Lindbæk Broman, Michael Åxman Petersen, Asbjørn Sune Andersson, Tanja Skouw Jensen, Kristine Kilså, and Anders Kadziola. "New routes to functionalized dihydroazulene photoswitches." Pure and Applied Chemistry 82, no. 4 (March 9, 2010): 843–52. http://dx.doi.org/10.1351/pac-con-09-07-08.

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Molecular photoswiches are important for the development of advanced materials and molecular electronics devices. The dihydroazulene (DHA) is a particularly attractive molecule as it undergoes a light-induced ring opening to a vinylheptafulvene (VHF) isomer with altered optical properties. While functionalization of the five-membered ring of DHA has been possible for the last 25 years, this was not the case for the seven-membered ring. This article summarizes our synthetic efforts in achieving this goal. Incorporation of an alkyne at C-7 was accomplished by (i) regioselective bromination of DHA, followed by (ii) elimination of HBr, and (iii) Pd-catalyzed cross-coupling with triisopropylsilylacetylene. Light-induced ring opening of this DHA followed by thermal ring closure provided a mixture of 6- and 7-substituted DHAs with different absorption characteristics. The isomer ratio was controlled by the wavelength of irradiation and the solvent polarity. The dibromide formed in the initial step served as a precursor for a 3-bromo-functionalized azulene that was employed as a building block for acetylenic scaffolding. Incorporation of a dithiafulvene (DTF) unit at the five-membered ring of DHA resulted in a significant red-shift in the longest-wavelength absorption and consequently a lowering of the energy required for ring opening. Incorporation of a redox-active tetrathiafulvalene (TTF) unit allowed for redox-controlled photoswitching.

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El-Bindary, Ashraf, Hala Kiwaan, Abdel Ghany Shoair, Fawzia El-Ablack, and Ahmed Eessa. "Synthesis and characterization of hyperbranched silane-modified alkyd as a polymer for environmentally friendly low VOC polyurethane coatings." Pigment & Resin Technology 49, no. 2 (August 31, 2019): 102–9. http://dx.doi.org/10.1108/prt-10-2018-0108.

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Purpose The purpose of this paper is to introduce a new method for modification of alkyd resin by using 3-triethoxysilylpropyl succinic acid anhydride (TESP-SA) as the core material for low volatile organic components (VOCs) polyurethane coating applications. Design/methodology/approach The structural, physical, thermal and film properties of the silane-modified (SM) alkyd were evaluated and compared with those of a silane-free alkyd resin that was prepared by a single-step method. The synthesis reaction was described in a detailed scheme and evidenced by ATR-FTIR measurements and 13C-NMR spectroscopy. Findings SM alkyd has synthesized with high solid content (85%) and low viscosity (5700 cP). As a result, environmentally friendly coatings with lower (VOC) emission are possible by using this type of alkyd polymer. The results showed that the presence of the Si atom in the final structure improved the thermal stability against the higher levels of aromatic rings in the silane-free alkyd. It was found that coatings based on SM alkyd have lower values of yellowing factor (Δa) and an increase of gloss retention percentage at different intervals of exposure to the quick ultraviolet weathering conditions. Practical implications The synthesized SM alkyd resin provided a practical solution to obtain environmentally friendly coatings with low VOC content, in addition to its improvement in alkyds’ overall characteristics, while still using natural resources – fatty acids – instead of totally petroleum resources. Originality/value TESP-SA has not been used before in alkyd polymer modifications, and this study can help countries that are interested in using environmentally-friendly coatings.

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Sagdic, Gokhan, Emrah Cakmakci, Ozgun Daglar, Ufuk Saim Gunay, Gurkan Hizal, Umit Tunca, and Hakan Durmaz. "Thermal and mechanical properties of thiol-ene photocured thermosets containing DOPO-based liquid reactive flame retardant synthesized by metal-free azide-alkyne click reaction." Progress in Organic Coatings 167 (June 2022): 106825. http://dx.doi.org/10.1016/j.porgcoat.2022.106825.

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Zafar, Fahmina, Syed Marghoob Ashraf, and Sharif Ahmad. "Self-cured polymers from non-drying oil." Chemistry & Chemical Technology 2, no. 4 (December 15, 2008): 285–93. http://dx.doi.org/10.23939/chcht02.04.285.

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Pongamia glabra seed oil (PGSO) – a non-edible, non-drying oil; a sustainable resource has found application as alkyds, epoxies and polyesteramides in paints and coatings. Generally, PGSO based polymeric coatings are obtained by curing at elevated temperature. Efforts have been made to cure PGSO at room temperature by simple route modification. Self-cured Pongamia glabra oil based on polyesteramide (APGPEA) resin was synthesized by the reaction between Pongamia glabra oil modified fatty amide diol (HEPGA) with polystyrene co-maleic anhydride (SMA). After complete synthesis of APGPEA, phthalic anhydride modified polyesteramide (APGPEAPh) was synthesized in situ by a minor addition of phthalic anhydride (PA) to APGPEA in order to improve the performance of the latter. The effect of the SMA and PA introduction on properties of PGPEAPh film was also investigated. The physico-chemical characteristics of both resins were obtained by standard laboratory methods. The structural elucidation of these resins was carried out by FT-IR, 1H-NMR and 13C-NMR spectral techniques. The thermal behavior was studied by TGA. Curing was studied by DSC and FT-IR techniques. It was observed that APGPEA and APGPEAPh resins significantly improve the drying property in contrast to the previously reported polyesteramides cured at high temperature. Physico-mechanical and chemical/corrosion resistance tests of APGPEAPh coatings showed that the presence of phthalic anhydride in APGPEA enhanced the physico-mechanical and corrosion resistance considerably. The APGPEAPh resin appears to be sustainable aspirant biomaterials for anticorrosive surface coatings which may substitute polymers obtained from petroleum, potentially scarce resource.

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Santos, Jose, Pavel Jelínek, David Ecija, and Nazario Martin. "(Invited) On-Surface Synthesis of Acene Polymers." ECS Meeting Abstracts MA2022-01, no. 11 (July 7, 2022): 811. http://dx.doi.org/10.1149/ma2022-0111811mtgabs.

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The design and study of π-conjugated polymers has received great attention along the last decades. The relevant optical and electronic properties stemming from their delocalised π-electrons allow for a number of applications in the emerging field of organic electronics. However, the inherent limited solubility of planar π-conjugated systems hinders their development, forcing chemists to introduce ancillary solubilising side-chains. On the other hand, ultrahigh-vacuum on-surface synthesis has become a powerful discipline that enables designing with atomistic precision a new plethora of molecular compounds, polymers, and nanomaterials that otherwise are unachievable by conventional organic chemistry. Herein we present a novel on-surface chemical transformation that allows obtaining π-conjugated acene polymers from simple aromatic molecules carrying =CBr2 functionalities. The deposition of such precursors on an Au(111) surface gives rise to close-packed assemblies. Thermal annealing promotes the debromination of the species that thereafter homocouple and give rise to long anthracene wires linked by acetylene bridges, featuring a bandgap of 1.5 eV (see figure below). When larger acenes or periacenes are used (i.e. pentacene, bisanthene, peripentacene) the resulting polymers undergo dramatic structural and electronic changes. Non-contact-AFM evince that the benzoid subunits evolve from aromatic (anthracene) to quinoid (pentacene, bisanthene...), while the alkyne linkers turn into cumulenic. The STM images allow witnessing the HOMO-LUMO levels crossing from anthracene to pentacene. This swap destabilises the aromatic structure and enables a biradical-quinoid one, that permit almost vanishing bandgaps below 0.35 eV. These findings can also be rationalised by topological band gap theory: DFT, tight binding and GW calculations predict that polymers these quasi-metallic polymers exhibit a topologically non-trivial electronic structure. Our results herald novel pathways to engineer π-conjugated polymers on solid surfaces, addressing the relevant family of acenes and, thus, contributing to develop the field of on-surface chemistry and to steer the design of modern low bandgap polymers. Figure 1

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Majed Jari Mohammed, Majed Jari Mohammed, Abdul Amir H. Kadhum Abdul Amir H Kadhum, and Adnan Ibrahim Mohammed and Sameer H. Abbood Al Rekabi Adnan Ibrahim Mohammed and Sameer H Abbood Al Rekabi. "Synthesis of One New Sugar Imine Molecule." Journal of the chemical society of pakistan 42, no. 1 (2020): 103. http://dx.doi.org/10.52568/000622.

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In this research, the molecule Nand#39;-((E)-5-methoxy-2-((1-((2R,3R,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydro-2H-pyran-2-yl)-4,5-dihydro-1H-1,2,3-triazol-4-yl)methoxy) benzylidene)-4-methyl-1,2,3-thiadiazole-5-carbohydrazide were synthesized and characterized by several conventional analysis methods. Its physical properties and thermal stability was studied. The synthesis was conducted based on D-glucose using concept of click chemistry reaction mechanism. Some of the reaction was conducted using microwave irradiation. The synthesis steps initiated by adding propargyl bromide to 2- hydroxy-5-methoxy benzaldehyde under vigorous measure of moister isolated environment to produce propargyl ether(5-methoxy-2-(prop-2-yn-1-yloxy)benzaldehyde) 3 in which has terminal triple bond. In parallel a glycocyl azide was prepared by applying glycocyl acetate (acetate for protection) via bromination and then substituted by treatment with sodium azide to produce glycocyl azide in which actively reacted with terminated triple bond by click reaction in the present of Cu(II) catalyst. The coupling reaction of terminal alkyle group in compound 3 with azide group of (2R,3R,4S,5R,6R)-2-(acetoxymethyl)-6-azidotetrahydro-2H-pyran-3,4,5-triyl triacetate) has given high yield of triazole. The produced triazole molecule is triazole(2R,3R,4S,5R,6R)-2-(acetoxymethyl)-6-(4-((2-formyl-4-methoxy)methyl)-1H-1,2,3-triazole-1-yl)tetrahydro-2H-pyran-3,4,5,-triyacetate) 7 undergoes further reaction to substitute carbonyl of the aromatic with hydrazide by applying 4-methyl-1,2,3-thiadiazole-5-carbohydrazide reagent. The glycocyl acetate was de-esterifide by sodium methoxide to remove the acetate protection. The structure of all these synthesized molecules was confirmed by FTIR, H1NMR, C13 NMR.

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Majed Jari Mohammed, Majed Jari Mohammed, Abdul Amir H. Kadhum Abdul Amir H Kadhum, and Adnan Ibrahim Mohammed and Sameer H. Abbood Al Rekabi Adnan Ibrahim Mohammed and Sameer H Abbood Al Rekabi. "Synthesis of One New Sugar Imine Molecule." Journal of the chemical society of pakistan 42, no. 1 (2020): 103. http://dx.doi.org/10.52568/000622/jcsp/42.01.2020.

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In this research, the molecule Nand#39;-((E)-5-methoxy-2-((1-((2R,3R,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydro-2H-pyran-2-yl)-4,5-dihydro-1H-1,2,3-triazol-4-yl)methoxy) benzylidene)-4-methyl-1,2,3-thiadiazole-5-carbohydrazide were synthesized and characterized by several conventional analysis methods. Its physical properties and thermal stability was studied. The synthesis was conducted based on D-glucose using concept of click chemistry reaction mechanism. Some of the reaction was conducted using microwave irradiation. The synthesis steps initiated by adding propargyl bromide to 2- hydroxy-5-methoxy benzaldehyde under vigorous measure of moister isolated environment to produce propargyl ether(5-methoxy-2-(prop-2-yn-1-yloxy)benzaldehyde) 3 in which has terminal triple bond. In parallel a glycocyl azide was prepared by applying glycocyl acetate (acetate for protection) via bromination and then substituted by treatment with sodium azide to produce glycocyl azide in which actively reacted with terminated triple bond by click reaction in the present of Cu(II) catalyst. The coupling reaction of terminal alkyle group in compound 3 with azide group of (2R,3R,4S,5R,6R)-2-(acetoxymethyl)-6-azidotetrahydro-2H-pyran-3,4,5-triyl triacetate) has given high yield of triazole. The produced triazole molecule is triazole(2R,3R,4S,5R,6R)-2-(acetoxymethyl)-6-(4-((2-formyl-4-methoxy)methyl)-1H-1,2,3-triazole-1-yl)tetrahydro-2H-pyran-3,4,5,-triyacetate) 7 undergoes further reaction to substitute carbonyl of the aromatic with hydrazide by applying 4-methyl-1,2,3-thiadiazole-5-carbohydrazide reagent. The glycocyl acetate was de-esterifide by sodium methoxide to remove the acetate protection. The structure of all these synthesized molecules was confirmed by FTIR, H1NMR, C13 NMR.

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Yang, Haicun, Zinan Cai, Haotian Liu, Zheng Cao, Yanping Xia, Wenzhong Ma, Fanghong Gong, Guoliang Tao, and Chunlin Liu. "Tailoring the surface of attapulgite by combining redox-initiated RAFT polymerization with alkynyl-thiol click reaction for polycarbonate nanocomposites:Effect of polymer brush chain length on mechanical, thermal and rheological properties." Materials Chemistry and Physics 241 (February 2020): 122334. http://dx.doi.org/10.1016/j.matchemphys.2019.122334.

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Xia, Chun-Gu, Simon G. Bott, and Michael G. Richmond. "Reaction of the dicobalt alkyne compound Co2(CO)6( -dmad) with the diphosphine ligand 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd). Spectroscopic properties, X-ray diffraction data, and thermal reactivity of the chelating isomer of Co2(CO)4(bpcd)( -dmad)." Journal of Chemical Crystallography 34, no. 8 (August 2004): 513–21. http://dx.doi.org/10.1023/b:jocc.0000042019.54785.9a.

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Zerbib, Souad, Mostafa Khouili, Marco Catto, and Latifa Bouissane. "Sydnone: Synthesis, reactivity and biological activities." Current Medicinal Chemistry 29 (June 20, 2022). http://dx.doi.org/10.2174/0929867329666220620123050.

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Abstract: Sydnones are among the most well-known mesoionic compounds. Since their synthesis in 1935 by Earl and Mecknay, numerous researches have shown that the chemical behavior, physical and biological properties of sydnones make them among the most useful compounds in organic chemistry. Sydnones undergo thermal 1,3-dipolar cycloaddition reaction with dipolarophiles (alkynes or alkenes) to give exclusively derivatives containing a pyrazole moiety exhibiting numerous applications such as pharmaceuticals and agrochemicals. However, the sydnone cycloaddition reaction with alkynes requires harsh conditions like high temperatures and long reaction times giving poor regioselectivity on the resulting products. To overcome these constraints, new reactions named CuSAC (Copper-Catalyzed Sydnone-Alkyne Cycloaddition) and SPSAC (Strain-Promoted Sydnone-Alkyne Cycloaddition) and have been developed, leading to pyrazoles with interesting constant kinetics.

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Fengling, Qing, Yao Rongxing, Wang Lianjun, Li Hongqi, and Meng Weidong. "Chemical modification of poly(vinylacetylene) via click reaction." e-Polymers 8, no. 1 (December 1, 2008). http://dx.doi.org/10.1515/epoly.2008.8.1.1580.

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AbstractChemical modification of poly(vinylacetylene) (PVacet) was performed through click reactions by which alkyl and fluoroalkyl groups were introduced to the pendent terminal alkynes of PVacet. Novel polymers containing 1,2,3-triazoles were consequently obtained and their structures and properties were characterized by FT-IR, 1H NMR, TGA, DSC and GPC. The polymers modified by alkyl groups had good solubility, thermal stability and reasonable molecular weights. It was also demonstrated that the properties of fluorine-containing polymers were affected by fluorine atoms with hydrophobic and chemical proof properties

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Vebr, aurélien, Magali Dallegre, Laurent Autissier, Charlotte Drappier, Karel Lejeune, Didier Gigmes, and Anthony Kermagoret. "Nitroxide mediated radical polymerization for the preparation of poly(vinyl chloride) grafted poly(acrylate) copolymers." Polymer Chemistry, 2022. http://dx.doi.org/10.1039/d2py00308b.

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In view to control the thermal properties of PVC without the use of toxic phthalate derivatives, alkoxyamines were grafted onto an azide modified PVC, through copper catalyzed azide-alkyne cycloaddition (CuAAC),...

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Ofori-Boadu, Andrea Nana, DeAndria Bryant, Christian Bock-Hyeng, Zerihun Assefa, Frederick Aryeetey, Samira Munkaila, and Elham Fini. "Physiochemical characterization of agricultural waste biochars for partial cement replacement." International Journal of Building Pathology and Adaptation ahead-of-print, ahead-of-print (March 31, 2021). http://dx.doi.org/10.1108/ijbpa-04-2020-0026.

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PurposeThe purpose of this study is to explore the feasibility of utilizing agricultural (almond shell, rice husk and wood) waste biochars for partial cement replacement by evaluating the relationships between the physiochemical properties of biochars and the early-age characteristics of cement pastes.Design/methodology/approachBiochars are prepared through the thermal decomposition of biomass in an inert atmosphere. Using varying percentages, biochars are used to replace ordinary Portland cement (OPC) in cement pastes at a water/binder ratio of 0.35. Characterization methods include XPS, FTIR, SEM, TGA, BET, Raman, loss-on-ignition, setting, compression and water absorption tests.FindingsAccelerated setting in biochar-modified cement pastes is attributed to chemical interactions between surface functional groups of biochars and calcium cations from OPC, leading to the early development of metal carboxylate and alkyne salts, alongside the typical calcium-silicate-hydrate (C-S-H). Also, metal chlorides such as calcium chlorides in biochars contribute to the accelerate setting in pastes. Lower compression strength and higher water absorption result from weakened microstructure due to poor C-S-H development as the high carbon content in biochars reduces water available for optimum C-S-H hydration. Amorphous silica contributes to strength development in pastes through pozzolanic interactions. With its optimal physiochemical properties, rice-husk biochars are best suited for cement replacement.Research limitations/implicationsWhile biochar parent material properties have an impact on biochar properties, these are not investigated in this study. Additional investigations will be conducted in the future.Practical implicationsCarbon/silicon ratio, oxygen/carbon ratio, alkali and alkaline metal content, chlorine content, carboxylic and alkyne surface functional groups and surface areas of biochars may be used to estimate biochar suitability for cement replacement. Biochars with chlorides and reactive functional groups such as C=C and COOH demonstrate potential for concrete accelerator applications. Such applications will speed up the construction of concrete structures and reduce overall construction time and related costs.Social implicationsReductions in OPC production and agricultural waste deterioration will slow down the progression of negative environmental and human health impacts. Also, agricultural, manufacturing and construction employment opportunities will improve the quality of life in agricultural communities.Originality/valueEmpirical findings advance research and practice toward optimum utilization of biomass in cement-based materials.

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Journal articles on the topic 'Alkynes Thermal properties'

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