Thermo-, pH-, and Light-Responsive Supramolecular Complexes Based on a Thermoresponsive Hyperbranched Polymer
Jing Zhang1, Hua-Ji Liu1, Yuan Yuan1
1Department of Chemistry, School of Sciences, Tianjin University, Tianjin 300072, People's Republic of China.
ACS Macro Letters
|May 18, 2022
Summary
Researchers created novel supramolecular complexes using hyperbranched polyethylenimine and 4-(phenylazo)benzoic acid. These thermoresponsive materials show tunable properties sensitive to pH and light, offering potential for advanced applications.
Area of Science:
- Polymer Chemistry
- Supramolecular Chemistry
- Materials Science
Background:
- Hyperbranched polyethylenimine (HPEI) derivatives are versatile polymers.
- Supramolecular complexation offers a route to engineer material properties.
- Thermoresponsive polymers are crucial for smart material applications.
Purpose of the Study:
- To synthesize and characterize supramolecular complexes of HPEI-IBAm and PABA.
- To investigate the thermoresponsive behavior and pH/photo-sensitivity of these complexes.
- To understand the influence of polymer topology and guest molecule content on complex properties.
Main Methods:
- Supramolecular complex formation via acid-base neutralization.
- Characterization using 1H and 2D NOESY 1H NMR spectroscopy.
- Cloud point temperature (Tcp) measurements under varying pH and light conditions.
Main Results:
- Supramolecular complexes of HPEI-IBAm and PABA were successfully formed and characterized.
- The complexes exhibited tunable thermoresponsive behavior (Tcp) sensitive to PABA content and pH.
- Reversible trans-to-cis photoisomerization of azobenzene units modulated Tcp, with opposite effects at pH ~7 and ~9.
Conclusions:
- HPEI-IBAm and PABA form water-soluble supramolecular complexes with tunable thermoresponsive properties.
- The cloud point temperature is sensitive to PABA content, pH, and light-induced azobenzene isomerization.
- Polymer topology significantly influences the thermoresponsive characteristics of the complexes.
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