A cosolvency effect on tunable thermosensitive core-shell nanoparticle gels

Area of Science:

• Polymer Science
• Materials Science
• Physical Chemistry

Background:

• Thermosensitive nanoparticle gels exhibit tunable swelling behavior.
• The core-shell structure of poly(methyl methacrylate) (PMMA) and poly(2-hydroxyethyl methacrylate) (PHEMA) influences their response to external stimuli.
• Understanding co-solvent effects is crucial for controlling gel properties.

Purpose of the Study:

• To investigate the influence of co-solvents (cyclohexane, 1,3-propanediol, water) on the swelling behavior of PMMA/PHEMA core-shell nanoparticle gels.
• To explore the cosolvency phenomenon and its impact on thermosensitive gels.
• To demonstrate the tunability of volume transition temperatures (VTTs) in these core-shell networks.

Main Methods:

• Synthesis of PMMA/PHEMA core-shell nanoparticle gels.
• Investigation of swelling behavior in the presence of co-solvents using thermo-optical analysis (TOA) and photon correlation spectroscopy (PCS).
• Theoretical modeling using multi-component lattice theory and the Flory-Rehner (F-R) chain model.

Main Results:

• Co-solvents (cyclohexane, 1,3-propanediol, water) significantly altered the swelling properties of the core-shell gels.
• A cosolvency phenomenon was observed, enhancing solvation effects even with low water content (1-3 wt%).
• Specific co-solvents induced distinct VTTs: CHX ('lower/upper'), PDO ('even/upper'), and water ('lower/lower').

Conclusions:

• The swelling behavior of thermosensitive core-shell nanoparticle gels can be precisely controlled by the addition of co-solvents.
• The combination of experimental techniques and theoretical modeling accurately predicts the observed swelling data.
• This study provides a foundation for designing advanced responsive polymer materials.