Polymer Microstructure Directs the Solvent-Selective Swelling Response of Polymer Brushes

Area of Science:

• Polymer Chemistry
• Materials Science
• Nanotechnology

Background:

• Polymer brushes are crucial for nanoparticle transport and sensing.
• Understanding their solvent-responsive properties is key for advanced applications.
• Solvent-selective swelling depends on polymer composition and microstructure.

Purpose of the Study:

• To investigate how polymer composition and microstructure influence polymer brush swelling.
• To compare the solvent-selective response of block vs. statistical copolymer brushes.
• To evaluate the potential of these polymer brushes in cell-interfacing applications.

Main Methods:

• Synthesized block and statistical copolymer brushes of 2-(dimethylamino)ethyl methacrylate (DMA) and 2-(diisopropylamino)ethyl methacrylate (DiPA).
• Tuned DMA/DiPA ratios and selectively quaternized DMA to modify solvophilicity.
• Measured brush swelling in water and isopropanol to assess solvent response.
• Evaluated cytocompatibility for cell-interfacing applications.

Main Results:

• Increasing DiPA content decreased brush swelling in water for both copolymer types.
• In isopropanol, block copolymer brushes exhibited significantly less swelling (9–37%) than statistical copolymers.
• Spatial distribution of solvophobic and solvophilic units, not just abundance, governs solvent responsivity.

Conclusions:

• Polymer brush microstructure is a critical determinant of solvent-responsive behavior.
• Block copolymer architecture offers distinct swelling control compared to statistical arrangements.
• These findings advance the design of smart polymer brushes for targeted applications.