Supramolecular Polymer Brushes Grafted via Atom Transfer Radical Polymerization from Surfaces Presenting...

Area of Science:

• Supramolecular Chemistry
• Polymer Science
• Surface Chemistry

Background:

• Supramolecular polymer brushes offer tunable properties through non-covalent interactions.
• Host-guest complexation provides a versatile platform for surface functionalization.
• Understanding the influence of binding strength on polymer brush characteristics is crucial.

Purpose of the Study:

• To synthesize supramolecular polymer brushes using adamantane-functionalized initiators and cyclodextrin/cucurbituril hosts.
• To investigate the impact of host-guest binding strength on polymer brush thickness and grafting density.
• To evaluate the robustness and stability of these supramolecular polymer brushes.

Main Methods:

• Surface-initiated atom transfer radical polymerization (ATRP) in aqueous media.
• Utilized adamantane-functionalized initiators noncovalently bound to β-cyclodextrin- or cucurbit[7]uril-modified substrates.
• Characterization of polymer brush thickness and grafting density.

Main Results:

• Successfully grew hydrophilic polymer brushes up to 40 nm thick from modified surfaces.
• Grafting density differences were smaller than predicted by solution binding constants between hosts and adamantane.
• Both β-cyclodextrin and cucurbit[7]uril anchored brushes exhibited remarkable robustness against polymer graft detachment.

Conclusions:

• The rapid kinetics of host-guest complex formation/dissociation, rather than binding strength, dictates polymer brush stability.
• Surface-grafted polymer brushes act as steric barriers, preventing individual chain detachment.
• This method enables surface-initiated polymerization even with weak host-guest interactions, expanding possibilities for functional surfaces.