Local Surface Chemistry Dynamically Monitored by Quantitative Phase Microscopy

Area of Science:

• Materials Science
• Surface Chemistry
• Optical Physics

Background:

• Surface modification via photografting is crucial for creating functional surfaces.
• Quantitative monitoring of photografting processes, especially in real-time, remains a challenge for precision applications.
• Existing methods often lack the sensitivity or operando capabilities required for detailed kinetic analysis.

Purpose of the Study:

• To present a novel, label-free, and cost-effective all-optical method for real-time monitoring of surface photografting.
• To enable quantitative tracking of grafted layer evolution with high sensitivity and resolution.
• To provide insights into photografting kinetics and optimize functionalization strategies.

Main Methods:

• Utilized wavefront sensing with a simple diffuser placed near a camera for label-free monitoring.
• Achieved sub-nanometric thickness sensitivity and diffraction-limited lateral resolution.
• Performed in-depth kinetic analysis of aryldiazonium salt photografting on glass substrates.

Main Results:

• Demonstrated quantitative real-time monitoring of both focused and widefield photografting.
• Characterized different growth regimes and estimated key parameters like grafting efficiency, density, and refractive index distribution.
• Validated the method's capability for precise surface micro- and submicro-structuration.

Conclusions:

• The proposed wavefront sensing technique offers a sensitive, flexible, and cost-effective solution for monitoring photografting.
• This method provides valuable data for optimizing surface functionalization and achieving precise control over grafted layers.
• The approach makes advanced surface micro-structuration accessible to a wider range of laboratories.