Emission Properties of Diblock Copolymers Composed of Poly(ethylene glycol) and Dense 1,2,3-Triazole Blocks

• Main Authors: Yanqiong Yang, Asami Mori, Akihito Hashidzume
• Format: Article
• Language: English
• Published: MDPI AG 2019-06-01
• Series: Polymers
• Subjects: emission properties; diblock copolymer; dense 1,2,3-triazole block; poly(ethylene glycol) block; copper(I)-catalyzed azide–alkyne cycloaddition polymerization
• Online Access: https://www.mdpi.com/2073-4360/11/7/1086

This article describes a new block copolymer (EG<i>m</i>-<i>b</i>-AP<i>n</i>, where <i>m</i> and <i>n</i> denote the degrees of polymerization) of poly(ethylene glycol) (PEG) and poly(1,4-(1-<i>H</i>-1,2,3-triazolylene)methylene) prepared by copper(I)-catalyzed azide–alkyne cycloaddition (CuAAC) polymerization of 3-azido-1-propyne (AP) in the presence of PEG carrying a propargyl moiety. The EG<i>m</i>-<i>b</i>-AP<i>n</i> samples are well soluble in polar organic solvents. Unexpectedly, we observed that solutions of EG<i>m</i>-<i>b</i>-AP<i>n</i> in <i>N</i>,<i>N</i>-dimethylformamide emitted fluorescence. We systematically studied absorption and emission properties of the block copolymers. The experimental data have exhibited that AP<i>n</i> block is an intrinsic fluorophore. Interestingly, the emission of EG<i>m</i>-<i>b</i>-AP<i>n</i> can be easily tuned from ultraviolet to green fluorescence by changing the excitation wavelength. This enables fine-tuning of its optical property without the need of changing the chromophore. Moreover, the block copolymers show a fluorescence response to metal ions (e.g., Cu²⁺). Our discoveries contribute to the fundamental understanding of the optical properties of dense triazole-based polymer and raise intriguing prospects for fabricating novel emissive triazole-based materials.