Photo-activated Polymers

hyPIRTM Imaging of Photo-activated Polymer Functionalization

azobenzene pifm work hyPIR

These 10 μm images (AFM topography and PiFM) are being acquired as azobenzene surface is being modified via UV light illumination over a 15-hour period. The PiFM image at 1100 cm-1 shows that as the surface roughens, the magnitude of this peak is growing smaller. At the same time, PiFM signal at 1693 cm-1 is getting stronger at some regions of the sample, especially at the lower regions of the surface features.

The azobenzene was exposed to our top objective’s illumination LED for 15 hours while a slow hyPIRTM image was being acquired. The CCD pictures below are after 15 hours of exposure to LED light:

azobenzene pifm work hyPIR 2

azobenzene pifm work hyPIR 3

The three spectra (colored red, green, black) are spectra obtained by averaging the spectra defined by the masks of the same color in the grayscale image next to the spectra.  Looking at the spectra, it is clear that the peaks at ~1100, 1270, and 1520 cm-1 have gotten smaller with exposure while the broad peak between 1660 to 1750 cm-1 has grown significantly.  By combining the red image (PiFM intensity map at ~ 1100 cm-1) and the green image (PiFM intensity map at 1660 to 1750 cm-1), the combined image shows the progression graphically. By combining the PiFM intensity map at 1660 to 1750 cm-1 with 3D AFM topography, we can also see what topographical features are associated with the new peak.