Spiropyran Functionalized Surfaces
Spiropyran Functionalized Surfaces Zoey Y. Sowinski1, Martha E. Grady2,3, Nancy R. Sottos1,3 1Department
of Materials Science and Engineering 2Department of Mechanical Science and Engineering 3Frederick Seitz Materials Research Laboratory, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign
Objectives
Results: Raman Spectroscopy
Method
• Functionalize a dielectric substrate using self-assembled monolayers (SAMs) • Characterize the activation of spiropyran using water contact angle goniometry and Raman spectroscopy • Determine photosensitivity of spiropyran functionalized surfaces
Piranha Clean Substrate
SAM Bath: 1 hour
Sonicate, Rinse, Dry
Background
Active SP
Spiropyran Functionalization
[∗]
Bath Preparation
SP Bath: 24 hours
Sonicate, Rinse, Dry
APS + TBDS
Surface Characterization
platform for
• Spiropyran (SP) is a mechanophore -- molecular unit which reacts to a change in the mechanical state of a material • When activated, breaks spiro bond [∗] and “opens” structure to form merocyanine (MC)
APS only
Amine-terminated SAM Functionalization
Surface Characterization
Surface Characterization
Force, heat, UV
Monolayer Thickness Measurements
Visible light
Surface Roughness Measurements
Mono SP
• MC is highly colorful, fluorescent, more hydrophilic than spiropyran
Materials Active Interfacial SP
• Fluorescent peaks indicate activation of spiropyran • Addition of TBDS resulted in higher peaks
Monofunctional Interfacial SP
Conclusions • Schematic of Ideal Surface Functionalization • Left: Ellipsometry (left) quantifies the thickness of the SAM platform and the additional spiropyran layer • Right: Atomic Force Microscopy (AFM) measurements indicate a smooth, uniform surface is maintained
Results: Water Contact Angle (APS)
Si/TBDS+APS/SP (46.5°)
Si/TBDS+APS/SP (54.8°)
(TBDS)
UV exposure
SAM platform
scale bars are 100 μm
• Active spiropyran shows a decrease in water contact angle of about 8°, indicating the surface is more hydrophilic
• Spiropyran-functionalization resulted in a 7 Å increase in thickness and a consistent, smooth surface • UV-induced activation of spiropyran resulted in a decrease in water contact and a fluorescent peak in the Raman spectra • Side groups off the spiropyran molecule affected reactivity • Proximity of nearest neighboring SP molecules can prevent efficient conversion to MC form
Future Directions
• Demonstrate mechanical activation of spiropyran-functionalized surfaces • Investigate SP interfacial monolayers as marker for film delamination
Acknowledgements Beckman Institute, Frederick Seitz Materials Research Laboratory, Semiconductor Research Corporation, National Science Foundation
of Materials Science and Engineering 2Department of Mechanical Science and Engineering 3Frederick Seitz Materials Research Laboratory, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign
Objectives
Results: Raman Spectroscopy
Method
• Functionalize a dielectric substrate using self-assembled monolayers (SAMs) • Characterize the activation of spiropyran using water contact angle goniometry and Raman spectroscopy • Determine photosensitivity of spiropyran functionalized surfaces
Piranha Clean Substrate
SAM Bath: 1 hour
Sonicate, Rinse, Dry
Background
Active SP
Spiropyran Functionalization
[∗]
Bath Preparation
SP Bath: 24 hours
Sonicate, Rinse, Dry
APS + TBDS
Surface Characterization
platform for
• Spiropyran (SP) is a mechanophore -- molecular unit which reacts to a change in the mechanical state of a material • When activated, breaks spiro bond [∗] and “opens” structure to form merocyanine (MC)
APS only
Amine-terminated SAM Functionalization
Surface Characterization
Surface Characterization
Force, heat, UV
Monolayer Thickness Measurements
Visible light
Surface Roughness Measurements
Mono SP
• MC is highly colorful, fluorescent, more hydrophilic than spiropyran
Materials Active Interfacial SP
• Fluorescent peaks indicate activation of spiropyran • Addition of TBDS resulted in higher peaks
Monofunctional Interfacial SP
Conclusions • Schematic of Ideal Surface Functionalization • Left: Ellipsometry (left) quantifies the thickness of the SAM platform and the additional spiropyran layer • Right: Atomic Force Microscopy (AFM) measurements indicate a smooth, uniform surface is maintained
Results: Water Contact Angle (APS)
Si/TBDS+APS/SP (46.5°)
Si/TBDS+APS/SP (54.8°)
(TBDS)
UV exposure
SAM platform
scale bars are 100 μm
• Active spiropyran shows a decrease in water contact angle of about 8°, indicating the surface is more hydrophilic
• Spiropyran-functionalization resulted in a 7 Å increase in thickness and a consistent, smooth surface • UV-induced activation of spiropyran resulted in a decrease in water contact and a fluorescent peak in the Raman spectra • Side groups off the spiropyran molecule affected reactivity • Proximity of nearest neighboring SP molecules can prevent efficient conversion to MC form
Future Directions
• Demonstrate mechanical activation of spiropyran-functionalized surfaces • Investigate SP interfacial monolayers as marker for film delamination
Acknowledgements Beckman Institute, Frederick Seitz Materials Research Laboratory, Semiconductor Research Corporation, National Science Foundation
