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Facile Preparation and Properties of Crosslinked Copolyether Elastomers with 1,2,3-Triazole and Urethane Subunit via Click Polymerization.

ABSTRACT: An azide terminated ethylene oxide-tetrahydrofuran copolymer with urethane segments (ATUPET) as a novel binder pre-polymer, has been prepared through ethylene oxide-tetrahydrofuran random copolymer (PET) end-capping modification via one-pot method. The structure characterization of the modifier has been analyzed by FTIR, ¹H NMR, ¹³C NMR and GPC. In comparison with PET, ATUPET has a slightly higher viscosity because it has additional hydrogen bonding interaction generated by the urethane in ATUPET. Triazole cross-linked elastomers based on ATUPET with various functional molar ratios were prepared using tripropargylamine as a curing agent and cross-linker. Mechanical properties indicate that the modulus E and tensile strength ? _b exhibit a parabolic dependence with the increase in R. At around the stoichiometric ratio, the modulus E and tensile strength ? _b reach a maximum and the elongation at break exhibit an acceptable value at the same time. Swelling tests demonstrate that the apparent cross-linking densities (N₀) have a maximum value at the stoichiometric ratio. Thermal analysis shows that the ATUPET prepolymer and its polytriazoles elastomers exhibit a satisfactory stability. The results demonstrated that ATUPET might be a promising polymeric binder for future propellant formulations especially in the field of isocyanate-free curing technology.

SUBMITTER: Zhang Q

PROVIDER: S-EPMC6496403 | biostudies-literature | 2019 May

REPOSITORIES: biostudies-literature

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Facile Preparation and Properties of Crosslinked Copolyether Elastomers with 1,2,3-Triazole and Urethane Subunit via Click Polymerization.

Zhang Qian Q Liu Ning N Mo Hongchang H Lu Xianming X Wang Yao Y Xu Minghui M Shu Yuanjie Y

ChemistryOpen 20190417 5

An azide terminated ethylene oxide-tetrahydrofuran copolymer with urethane segments (ATUPET) as a novel binder pre-polymer, has been prepared through ethylene oxide-tetrahydrofuran random copolymer (PET) end-capping modification via one-pot method. The structure characterization of the modifier has been analyzed by FTIR, <sup>1</sup>H NMR, <sup>13</sup>C NMR and GPC. In comparison with PET, ATUPET has a slightly higher viscosity because it has additional hydrogen bonding interaction generated by ...[more]

PMID: 31065507

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Project description:Molecular switching processes are important in a range of areas including the development of molecular machines. While there are numerous organic switching systems available, there are far less examples that exploit inorganic materials. The most common inorganic switching system remains the copper(I)/copper(II) switch developed by Sauvage and co-workers over 20 years ago. Herein, we examine if bidentate 2-(1-benzyl-1H-1,2,3-triazol-4-yl)pyridine (pytri) and tridentate 2,6-bis[(4-phenyl-1H-1,2,3-triazol-1-yl)methyl]pyridine (tripy) moieties can be used to replace the more commonly exploited polypyridyl ligands 2,2'-bypyridine (bpy)/1,10-phenanthroline (phen) and 2,2';6',2″-terpyridine (terpy) in a copper(I)/(II) switching system. Two new ditopic ligands that feature bidentate (pytri, L1 or bpytri, L2) and tridentate tripy metal binding pockets were synthesized and used to generate a family of heteroleptic copper(I) and copper(II) 6,6'-dimesityl-2,2'-bipyridine (diMesbpy) complexes. Additionally, we synthesized a series of model copper(I) and copper(II) diMesbpy complexes. A combination of techniques including nuclear magnetic resonance (NMR) and UV-vis spectroscopies, high-resolution electrospray ionization mass spectrometry, and X-ray crystallography was used to examine the behavior of the compounds. It was found that L1 and L2 formed [(diMesbpy)Cu(L1 or L2)]2+ complexes where the copper(II) diMesbpy unit was coordinated exclusively in the tridenate tripy binding site. However, when the ligands (L1 and L2) were complexed with copper(I) diMesbpy units, a complex mixture was obtained. NMR and MS data indicated that a 1:1 stoichiometry of [Cu(diMesbpy)]+ and either L1 or L2 generated three complexes in solution, the dimetallic [(diMesbpy)2Cu2(L1 or L2)]2+ and the monometallic [(diMesbpy)Cu(L1 or L2)]+ isomers where the [Cu(diMesbpy)]+ unit is coordinated to either the bidentate or tridentate tripy binding sites of the ditopic ligands. The dimetallic [(diMesbpy)2Cu2(L1 or L2)](PF6)2 complexes were structurally characterized using X-ray crystallography. Both complexes feature a [Cu(diMesbpy)]+ coordinated to the bidentate (pytri or bpytri) pocket of the ditopic ligands (L1 or L2), as expected. They also feature a second [Cu(diMesbpy)]+ coordinated to the nominally tridentate tripy binding site in a four-coordinate hypodentate κ2-fashion. Competition experiments with model complexes showed that the binding strength of the bidentate pytri is similar to that of the κ2-tripy ligand, leading to the lack of selectivity. The results suggest that the pytri/tripy and bpytri/tripy ligand pairs cannot be used as replacements for the more common bpy/phen-terpy partners due to the lack of selectivity in the copper(I) state.

Project description:The purpose of this work was to investigate the effect of multifunctionality on material properties of synthetic polymer aerogels. For this purpose, we present the synthesis and characterization of monolithic dendritic-type urethane-acrylate monomers based on an aliphatic/flexible (Desmodur N3300), or an aromatic/rigid (Desmodur RE) triisocyanate core. The terminal acrylate groups (three at the tip of each of the three branches, nine in total) were polymerized with 2,2'-azobis(isobutyronitrile) (AIBN) via free radical chemistry. The resulting wet-gels were dried with supercritical fluid (SCF) CO₂. Aerogels were characterized with ATR-FTIR and solid-state 13C NMR. The porous network was probed with N₂-sorption and scanning electron microscopy (SEM). The thermal stability of aerogels was studied with thermogravimetric analysis (TGA). Most aerogels were macroporous materials (porosity > 80%), with high thermal stability (up to 300 °C). Aerogels were softer at low monomer concentrations and more rigid at higher concentrations. The material properties were compared with those of analogous aerogels bearing only one acrylate moiety at the tip of each branch and the same cores, and with those of analogous aerogels bearing norbornene instead of acrylate moieties. The nine-terminal acrylate-based monomers of this study caused rapid decrease of the solubility of the growing polymer and made possible aerogels with much smaller particles and much higher surface areas. For the first time, aliphatic/flexible triisocyanate-based materials could be made with similar properties in terms of particle size and surface areas to their aromatic/rigid analogues. Finally, it was found that with monomers with a high number of crosslinkable groups, material properties are determined by multifunctionality and thus aerogels based on 9-acrylate- and 9-norbornene-terminated monomers were similar. Materials with aromatic cores are carbonizable with satisfactory yields (20⁻30% w/w) to mostly microporous materials (BET surface areas: 640⁻740 m² g-1; micropore surface areas: 360⁻430 m² g-1).

Dataset Information

Facile Preparation and Properties of Crosslinked Copolyether Elastomers with 1,2,3-Triazole and Urethane Subunit via Click Polymerization.

Publications

Facile Preparation and Properties of Crosslinked Copolyether Elastomers with 1,2,3-Triazole and Urethane Subunit via Click Polymerization.

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