Smart Copolymer Microgels with High Volume Phase Transition Temperatures: Composition, Swelling, and Morphology.

Area of Science:

• Polymer Chemistry
• Materials Science
• Nanotechnology

Background:

• Microgels are temperature-sensitive polymer networks with tunable properties.
• Increasing the volume phase transition temperature (VPTT) of microgels is crucial for higher operating temperature applications.
• Standard microgel monomers like N-isopropylacrylamide (NIPAM) have limited VPTTs.

Purpose of the Study:

• To investigate the effect of hydrophilic comonomers N-(hydroxymethyl)acrylamide (HMAM) and N-(2-hydroxyisopropyl)acrylamide (HIPAM) on microgel thermosensitivity and microstructure.
• To enhance the volume phase transition temperature (VPTT) of microgels.
• To explore the potential of these modified microgels for self-adaptive membranes in energy applications.

Main Methods:

• Copolymerization of standard microgel monomers with HMAM and HIPAM.
• Characterization using turbidimetry, Dynamic Light Scattering (DLS), and Atomic Force Microscopy (AFM).
• Analysis of swelling properties, microstructure, and VPTT.

Main Results:

• Incorporation of HMAM and HIPAM into microgels was precisely determined.
• Hydrophilic comonomers significantly increased microgel size, swelling capacity, and VPTT.
• Extrapolated VPTTs for pure HMAM and HIPAM microgels were 99 °C and 68 °C, respectively.
• Composition gradients within microgels were observed, influencing their properties.

Conclusions:

• Hydrophilic comonomers effectively increase the VPTT of microgels.
• Modified microgels exhibit unique microstructures and enhanced swelling behavior.
• These high-VPTT microgels show promise for developing advanced temperature-adaptive membranes for energy applications.