Liqiang Wan

Synthesis and Characterization of a Novel Polytriazole

p‐Xylylene diazide (XDA) and dipropargyl ether of bisphenol A (DPEBPA) were synthesized and then a novel polytriazole, poly(4,4′‐(propane‐2,2‐diyl) diphenyl‐oxy‐methylene‐1,5 (and 1,4)‐(1,2,3‐triazole)‐p‐xylene), was prepared from XDA and DPEBPA by 1,3‐dipolar cycloaddition polymerization and characterized by FTIR, 1H‐NMR, GPC, DSC, WAXD, TGA, etc. The results show that the polytriazole with the number average molecular weight of 9.77×104 is a partially crystalline polymer. The tensile strength and tensile modulus of the polytriazole film are 72.9 MPa and 2.95 GPa, respectively. The glass transition temperature of the polymer is 93.6°C and thermal decomposition temperature arrives at 350°C.

A novel polytriazole-based organogel formed by the effects of copper ions

A novel organogel in dimethyl formamide or dimethyl sulphoxide (DMF or DMSO), named GelT, was prepared by Cu(I)-catalyzed “click” reaction between diazide and dipropargyl bisphenol A. The action between copper ions and triazole rings was confirmed to be the mechanism of formation of the gel.

Novel Functional Polytriazole Elastomer with Thermal Stability and Adjustable Mechanical Properties

We proposed a novel functional polytriazole elastomer (PTE) with thermal stability and adjustable mechanical properties in this article. Attributed to the click chemistry utilized here, the bulk polymerization procedure was conducted efficiently at an amiable temperature. The novel elastomer was considered to be a promising elastomer with low glass transition temperature (Tg < 0°C) and excellent thermal stability (Td5 > 340°C) according to the thermal analysis results. In addition, tensile strength of PTE which ranged from 3.25MPa to 9.49MPa was easily adjusted by controlling the proportion of raw material used in the reaction.

Synthesis and characterization of a new series of rigid polytriazole resins

A novel series of polytriazole resins were synthesized by using aromatic diazides and N,N,N′,N′-tetrapropargyl-p,p′-diaminodiphenylmethane (TPDDM) as raw materials. The chemical structures of the resins were characterized by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance. Rheological behavior indicates that the resins can be processed in a low-temperature region, and some of them have good solubilities in common organic solvents. Differential scanning calorimetry and FTIR results demonstrated that the polytriazole resins can be cured at 70 °C. The glass transition temperature (T g) of cured resins increased with the increase in rigidity of diazide units in polymer chains and reaches up to 328 °C.

Synthesis and Characterization of a Novel Thermostable Polyether-Based Elastomeric Polytriazole via Click Reaction

We report the first synthesis and characterization of a novel thermostable polyether-based elastomeric polytriazole (EPTA) via click reaction. The EPTAs structure was confirmed by proton NMR characterization. The low glass transition temperatures (Tg < 0°C) of EPTAs ensure the product in elastomeric state at room temperature. The high 5% weight loss thermal decomposition temperatures (> 300°C) compared to other elastomeric polymers are the prominent property of the EPTAs. The influence of molecular weight of azide-terminated monomers and structures of dipropargyl ether monomers on the Tg and Td5 of EPTAs were studied.

New heat-resistant polytriazole adhesives: investigation of adhesion of polytriazole resins to metals

Crosslinkable polytriazole resins (CPTs) were synthesized by 1,3-dipolar cycloaddition reaction between azide and alkyne monomers. Adhesion properties of CPTs and an epoxy resin to different metal substrates (copper, iron and aluminium) were evaluated in terms of the tensile lap shear strength. CPTs to aluminium and iron substrates have higher adhesion strength than those to copper substrates. The effect of temperature and humidity on adhesion strength has been investigated. The resin CPT-3 has the best heat resistance among CPTs, whose retentions of adhesion strength are approximate 80% at 150 °C and 70% at 180 °C to all the substrates. CPTs have high adhesion properties at high temperature and humidity as compared with an epoxy resin.

A new high performance novolac-based polytriazole resin:

A novolac-based polytriazole (NPTA) resin was synthesized using 4,4′-diazidomethylbiphenyl and a propargylated novolac resin through catalyst-free click polymerization. Differential scanning calorimetry and Fourier transform infrared analysis results demonstrate that the NPTA resin can be cured at 80°C. The glass transition temperature of the cured NPTA-88 resin is 202°C. The thermal degradation temperature of the cured NPTA resin is 352°C under nitrogen. The composite of the resin exhibits good mechanical property.

A class of polytriazole metallogels via CuAAC polymerization: preparation and properties

A class of coordination-driven polytriazole metallogels were prepared via a copper(I)-catalyzed azide–alkyne cycloaddition (CuAAC) polymerization in a one-pot process. The properties of the obtained metallogels were characterized using Fourier transform infrared spectra, scanning electron microscopy, rheology and self-healing tests, etc. The coordination interactions between Cu+ and the polytriazoles were investigated through nuclear magnetic resonance, differential scanning calorimetry, and X-ray diffraction analysis techniques. The metallogels possess good thermal stability and exhibit strong self-healing abilities. The coordination interactions contribute to the physical cross-linking and interchain π–π aromatic stacking of polytriazole macromolecules, which result in network structure induced gelation.

Kinetic Study of Thermal Polymerization Reactions between Diazide and Different Diynes

The reaction kinetics between diazide(4,4’-biphenyl dibenzyl azide) and different diynes (dipropargyl bisphenol A and 1,3-diethynylbenzene) were studied by means of differential scanning calorimetry (DSC) and nuclear magnetic resonance spectroscopy (1H-NMR). DSC was adopted to analyze the reactions under bulk polymerization condition, while 1H-NMR for solution reaction polymerization was conducted. The apparent activation energies (Eα) calculated by Kissinger’s method were 77.96, 81.24 kJ/mol, which were confirmed by Friedman’s method, and 65.45, 69.36 kJ/mol by 1H-NMR for dispropargyl bisphenol A/4,4’-biphenyl dibenzyl azide and 1,3-diethynylbenzene/4,4’-biphenyl dibenzyl azide, respectively. The polymerizations between the diazide and diynes were first-order reactions based on calculation from both DSC and 1H-NMR. The results showed that the reaction between dipropargyl bisphenol A and 4,4’-biphenyl dibenzyl azide was easier than that between 1,3-diethynylbenzene and 4,4’-biphenyl dibenzyl azide, verifying that the reactivity of aliphatic alkyne was higher than that of aromatic alkyne.

Kinetic studies of CuBr-PMDETA catalyzed 1,3-dipolar cycloaddition polymerization

ABSTRACT The kinetics for the reaction of diazide (4,4′-biphenyl dibenzyl azide) and diyne (dipropargyl bisphenol A) catalyzed by CuBr-PMDETA (N, N, N′, N″, N″-pentamethyldiethylenetriamine) was studied in this paper by means of nuclear magnetic resonance spectra (1H-NMR) and differential scanning calorimetry (DSC). 1H-NMR was carried out to analyze solution polymerizations under different CuBr-PMDETA ratios in DMSO-d6. The results showed that CuBr-PMDETA catalytic system was easy to be oxidation under ambient condition. However, different CuBr-PMDETA ratios influenced the catalytic efficiency and the optimal ratios were found in nitrogen gas. DSC was carried out to analyze bulk polymerizations. The results showed that the apparent activation energy (Eα) calculated by Kissingers method was 69.2 kJ/mol, which was confirmed by Friedmans method. The two tests indicated that the catalyzed polymerization of diazide and diyne was a second order reaction.