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Selective Area Modification of Silicon Surface Wettability by Pulsed UV Laser Irradiation in Liquid Environment
Published on: November 9, 2015
Creating responsive surfaces with tailored wettability switching kinetics and reconstruction reversibility
1Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27695-7905, USA.
Journal of the American Chemical Society
|December 15, 2005
Summary
Responsive elastomer surfaces were created by modifying poly(vinylmethylsiloxane) networks. These surfaces exhibit tunable water-induced restructuring, with faster kinetics for shorter methylene spacers, enabling durable, low-hysteresis wettability switching.
Area of Science:
- Materials Science
- Polymer Chemistry
- Surface Science
Background:
- Responsive materials offer dynamic control over surface properties.
- Elastomers with tunable surface reconstruction are valuable for advanced applications.
- Controlling surface reorganization kinetics and hysteresis is crucial for material performance.
Purpose of the Study:
- To develop responsive surfaces with tailorable surface reconstruction kinetics and switching hysteresis.
- To investigate the effect of mercaptoalkanol chain length on surface behavior.
- To understand the mechanisms governing surface reorganization and wettability switching.
Main Methods:
- Thiolene radical addition of mercaptoalkanols to poly(vinylmethylsiloxane) networks.
- Fabrication of elastomer surfaces with varying methylene spacer lengths (n).
- Water contact angle measurements to quantify wettability changes and kinetics.
- Infrared (IR) spectroscopy to detect structural changes like semicrystalline region formation.
Main Results:
- Surface reconstruction kinetics decreased with increasing methylene spacers (n).
- Fast response kinetics (e.g., ~2 degrees/s for n=3) observed for n=2 and n=6.
- Materials demonstrated switching longevity over 10 cycles with minimal hysteresis.
- Increased n (n=11) led to dramatically decreased surface reorganization and eventual surface freezing.
- Formation of semicrystalline regions correlated with sluggish kinetics and surface freezing.
Conclusions:
- Tailorable surface reconstruction kinetics and hysteresis achieved through controlled mercaptoalkanol chain length.
- Siloxane backbone flexibility ensures switching longevity and low hysteresis.
- Surface freezing due to semicrystalline regions limits responsiveness for longer chain lengths.
- These findings enable the design of advanced responsive materials with predictable surface behavior.
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