Surface-Initiated PET-RAFT via the Z-Group Approach

Area of Science:

• Polymer Chemistry
• Materials Science
• Surface Science

Background:

• Surface-initiated reversible addition-fragmentation chain transfer (SI-RAFT) is key for polymer brush engineering.
• Existing SI-RAFT methods primarily focus on anchoring RAFT chain transfer agents (CTAs) via their R-group.
• The Z-group approach for SI-RAFT remains less explored.

Purpose of the Study:

• To investigate the Z-group approach for light-mediated SI-PET-RAFT polymerization.
• To demonstrate controlled polymer brush growth and chain extension using this method.
• To explore the potential for creating complex polymer brush architectures.

Main Methods:

• Synthesis and immobilization of a RAFT CTA onto SiO₂ via its Z-group.
• SI-PET-RAFT polymerization of acrylamide and methacrylate monomers in organic and aqueous media.
• Characterization using X-ray photoelectron spectroscopy (XPS), ellipsometry, and water contact angle measurements.

Main Results:

• Successful control over polymer brush growth and chain extension was achieved.
• The Z-group SI-PET-RAFT polymerization demonstrated oxygen tolerance, enabling ambient condition reactions.
• Grafting densities ranged from 0.01 to 0.16 chains nm^-2.
• The method allowed for the growth of intermittent polymer brush layers beneath the top layer without altering the outermost surface properties.

Conclusions:

• The Z-group SI-PET-RAFT approach offers a versatile alternative to traditional R-group methods.
• This technique enables precise control over polymer brush architecture, including multi-layered structures.
• The oxygen tolerance and patterning capabilities open new avenues for surface modification and functionalization.