Synthesis of Dense 1,2,3-Triazole Polymers Soluble in Common Organic Solvents.

Shota Yamasaki,Akihito Hashidzume,Linlin Xu,Yuri Kamon

doi:10.3390/polym13101627

Shota Yamasaki, Akihito Hashidzume + Show 2 more

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https://doi.org/10.3390/polym13101627

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Journal: Polymers	Publication Date: May 17, 2021
Citations: 16	License type: CC BY 4.0

Affiliation: Osaka University

Abstract

Aiming at synthesis of dense 1,2,3-triazole polymers soluble in common organic solvents, a new 3-azido-1-propyne derivative, i.e., t-butyl 4-azido-5-hexynoate (tBuAH), was synthesized and polymerized by copper(I)-catalyzed azide–alkyne cycloaddition (CuAAC) and Huisgen cycloaddition (HC). CuAAC polymerization produced poly(tBuAH) composed of 1,4-disubstituted 1,2,3-triazole units (1,4-units), whereas HC polymerization gave poly(tBuAH) composed of 1,4- and 1,5-disubstituted 1,2,3-triazole units (1,4- and 1,5-units). In HC polymerization, the fraction of 1,4-unit (f1,4) decreased with the permittivity of solvent used. Differential scanning calorimetry data indicated that the melting point of poly(tBuAH) increased from 61 to 89 °C with increasing f1,4 from 0.38 to 1.0, indicative of higher crystallinity of poly(tBuAH) composed of 1,4-unit. Preliminary steady-state fluorescence study indicated that all the poly(tBuAH) samples of different f1,4 emitted weak but significant fluorescence in DMF. The maximum of fluorescence band shifted from ca. 350 to ca. 450 nm with varying the excitation wavelength from 300 to 400 nm.

Highlights

We have been working on synthesis of dense 1,2,3-triazole polymers, and focusing of Huisgen cycloaddition (HC) or CuAAC polymerization of 3-azido-1-propyne (AP) derivatives that possess azide and alkyne moieties connected through a carbon atom
The remaining carboxylic acid moiety was coupled with N,O-dimethylhydroxylamine in the presence of 1-(3dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC), 1-hydroxybenzotriazole (HOBt), and N,N-diisopropylethylamine (DIPEA) to form a Weinreb amide (3)
The t-butyl ester side chain improved the solubility of polymer, resulting in the formation of high-molecular-weight poly(tBuAH)

Summary

Measurements

Sample solutions were filtrated with a DISMIC-13JP PTFE 0.50 μm filter just prior to injection. Differential scanning calorimetry (DSC) experiments were carried out with a DSC7020 differential scanning calorimeter (Hitachi High-Tech Science Corporation (Tokyo, Japan)) under a stream of nitrogen (200 mL min−1 ). DSC curves were recorded during three thermal scan cycles composed of heating, hold for 5 min, cooling, and hold for 5 min in a temperature range of −50 to 200 ◦ C. Steady state fluorescence spectra were recorded on a HITACHI F-2500 spectrophotometer using a 1.0 cm path length quartz cuvette at 25 ◦ C.

Materials

Polymerization of tBuAH

Results and Discussion

Synthesis and polymerization tBuAH

H NMR samples obtained by HC polymerization using

Conclusions