LCST-Type Hyperbranched Poly(oligo(ethylene glycol) with Thermo- and CO₂ -Responsive Backbone

Area of Science:

• Polymer Chemistry
• Materials Science
• Supramolecular Chemistry

Background:

• Polymers with tunable phase transition behaviors are crucial for advanced applications.
• Lower Critical Solution Temperature (LCST) polymers exhibit inverse temperature-dependent solubility.
• Developing stimuli-responsive polymers for CO2 and temperature is an active research area.

Purpose of the Study:

• To synthesize and characterize a novel hyperbranched polymer with dual temperature and CO2 responsiveness.
• To investigate the phase transition behavior of the polymer in aqueous solutions.
• To explore the tunability of the polymer's LCST by CO2 interaction.

Main Methods:

• Synthesis of hyperbranched poly(oligo(ethylene glycol)) (HBPOEG) using POEG backbone and tertiary amines.
• Phase transition studies through heating and cooling cycles in aqueous solutions.
• Investigation of CO2 and Nitrogen (N2) gas bubbling effects on polymer solubility and LCST.

Main Results:

• The synthesized HBPOEG demonstrated sharp, repeatable, concentration-dependent phase transitions.
• The polymer's LCST was effectively tuned by introducing CO2, which protonated tertiary amines and increased solubility.
• Reversible LCST modulation was achieved by removing CO2 with N2 gas.

Conclusions:

• A novel hyperbranched LCST polymer with significant CO2 and temperature responsiveness was successfully created.
• The polymer's tunable properties via CO2 offer a promising mechanism for controlled phase transitions.
• Potential applications include drug delivery, gene transfection, and functional coatings due to its responsive nature.