Contact-Biocide TiO₂ Surfaces by Surface-Initiated Atom Transfer Radical Polymerization with Chemically Stable...

Area of Science:

• Materials Science
• Polymer Chemistry
• Surface Chemistry

Background:

• Surface-initiated atom transfer radical polymerization (SI-ATRP) enables functional polymer grafting from surfaces.
• Immobilizing initiators on metal surfaces is crucial for SI-ATRP.
• Phosphonic acid groups facilitate surface binding, while bromoisobutyramide moieties enable SI-ATRP.

Purpose of the Study:

• To investigate the effect of alkyl spacer length in bifunctional initiators on polymer grafting from titanium surfaces.
• To create stable polycationic surfaces with antimicrobial properties.
• To establish an efficient SI-ATRP protocol avoiding toxic reagents.

Main Methods:

• Synthesis of bifunctional initiators with phosphonic acid and bromoisobutyramide groups.
• Surface modification of titanium using these initiators.
• Surface-initiated atom transfer radical polymerization (SI-ATRP) of (vinylbenzyl)trimethylammonium chloride (VBTAC).
• Analysis of polymer thickness, charge density, and antimicrobial activity.

Main Results:

• Polymer grafting thickness increased with initiator spacer length.
• Achieved high surface charge densities (∼10^16 N+/cm^2).
• Modified titanium surfaces demonstrated efficient contact activity against Staphylococcus aureus.
• SI-ATRP with VBTAC proved effective, bypassing post-grafting quaternization.

Conclusions:

• Bifunctional initiators with phosphonic acid groups are effective for SI-ATRP on titanium.
• Alkyl spacer length is a critical parameter for controlling polymer grafting.
• The developed method yields highly charged, antimicrobial surfaces without toxic reagents.