Preparation and post-functionalization of hyperbranched polyurea coatings

Area of Science:

• Polymer Chemistry
• Materials Science
• Surface Science

Background:

• Hyperbranched polymers offer unique network structures and tunable properties.
• Surface modification is crucial for advanced material applications.
• Controlled synthesis of functional polymers on substrates remains a challenge.

Purpose of the Study:

• To develop postfunctionalizable hyperbranched polyurea coatings on silicon substrates.
• To achieve covalent anchoring and tunable surface properties.
• To explore the modification of these coatings with various functional groups.

Main Methods:

• Bulk polycondensation of AB2 monomers (secondary amine and two blocked isocyanates) on silicon substrates.
• Covalent anchoring via reaction between the polymer's focal point amine and a coupling agent's blocked isocyanates.
• Postfunctionalization by heating to react surface-accessible blocked isocyanates with amino- or hydroxyl-functional compounds.
• Surface characterization using Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy, ellipsometry, and contact-angle measurements.

Main Results:

• Successfully prepared hyperbranched polyurea coatings with covalent substrate attachment.
• Demonstrated storage-stable yet heat-modifiable blocked isocyanates on the coating surface.
• Achieved tunable surface properties including hydrophilicity (polyethylene glycol), hydrophobicity (perfluoro-1-decanol), and high surface charge (polyethylenimine immobilization and quaternization).

Conclusions:

• Postfunctionalizable hyperbranched polyurea coatings can be synthesized with controlled surface properties.
• The developed coatings offer a versatile platform for creating tailored surfaces for diverse applications.
• The method allows for straightforward modification of surface chemistry through accessible reactive groups.