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Preparation of Stable Bicyclic Aziridinium Ions and Their Ring-Opening for the Synthesis of Azaheterocycles
Published on: August 22, 2018
The first example of main-chain cyclic azobenzene polymers.
Xu Xu1, Nianchen Zhou, Jian Zhu
1Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Materials Science of Soochow University, Suzhou 215123, P. R. China.
Macromolecular Rapid Communications
|May 14, 2011
Summary
A new cyclic azobenzene polymer, cyclic-PEHPA, was synthesized. This cyclic polymer exhibits enhanced thermal properties and improved photoisomerization compared to its linear counterpart, linear-PEHPA.
Area of Science:
- Polymer Chemistry
- Organic Synthesis
- Materials Science
Background:
- Azobenzene-containing polymers are known for their photoresponsive properties.
- Cyclic polymers often display distinct characteristics compared to their linear analogues.
- Developing novel cyclic polymers is crucial for advancing functional materials.
Purpose of the Study:
- To synthesize a novel main-chain azobenzene cyclic polymer, cyclic-PEHPA.
- To characterize the synthesized cyclic polymer and compare its properties with its linear precursor.
- To investigate the photoisomerization behavior of the cyclic azobenzene polymer.
Main Methods:
- Synthesis of linear azobenzene polymer (linear-PEHPA) via step-growth polymerization.
- 'Click' cyclization reaction to form the cyclic azobenzene polymer (cyclic-PEHPA).
- Characterization using Gel Permeation Chromatography (GPC), 1H NMR, and FT-IR spectroscopy.
Main Results:
- Successful synthesis of cyclic-PEHPA from linear-PEHPA precursors was confirmed.
- Cyclic-PEHPA demonstrated higher glass transition temperatures (Tg) compared to linear-PEHPA at similar molecular weights.
- Cyclic-PEHPA exhibited slightly improved trans-cis-trans photoisomerization ability, especially at lower molar masses.
Conclusions:
- The 'click' cyclization is an effective method for synthesizing main-chain azobenzene cyclic polymers.
- Cyclic azobenzene polymers offer potential advantages in thermal stability and photoresponsive applications.
- This study provides a new route to functional cyclic polymers with tunable properties.
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