This EArly-Concept Grant for Exploratory Research (EAGER) award will fund the development of polymers that are dually photo-crosslinkable and photolabile. A series of functional terpolymers will be synthesized that can be photo-crosslinked at long UV wavelengths and photo-chemically modified at short UV wavelengths. The terpolymers will be synthesized from three types of units: A structural unit, a photo-crosslinkable unit, and an acid unit with a photo-cleavable protecting group. The photo-crosslinking unit permits structural patterning of the polymer, and the photo-cleavable unit permits region-selective development of acidic regions in the pattern. The structural units to be tested include methylmethacrylate, N-isopropylacrylamide, and N,N-dimethylmethacrylamide. The kinetics of polymerization will be studied to establish the controllability of the final composition. Moreover, the efficiency of cross-linking and deprotection will be studied in thin film configurations.
If successful, the results of this research will provide polymers that are both structurally definable and photo-addressable. A major goal is to then combine conventional photolithography with assembly-based methods for the heterogeneous integration of nanoparticles into MEMS devices. Through the use of two different wavelengths of light, the photo-crosslinkable and photolabile polymers can be incorporated into MEMS devices and subsequently acid patterned through conventional photolithography. The regions of acidity, in turn, can direct the assembly of nanoparticles from solution to nanomanufacture multi-functional structures and surfaces.
This EAGER grant funded the development of polymers that are dually photo-crosslinkable and photolabile. A series of functional terpolymers were synthesized that can be photo-crosslinked at long UV wavelengths and photo-chemically modified at short UV wavelengths. The terpolymers were synthesized from three types of units: 1. A structural unit; 2. A photo-crosslinkable unit; and 3. An acid unit with a photo-cleavable protecting group. The photo-crosslinkable units are benzophenone derivatives that are capable of crosslinking at 365 nm. The photolabile units are p-methoxyphenacyl protected acid groups, which are photocleavable at 275 nm. P-methoxyphenacyl protected groups do not adsorb above 310 nm, which allows deprotection and cross-linking independently of one another. The structural unit is N-isopropylacrylamide. The photo-crosslinking unit permits structural patterning of the polymer, and the photo-cleavable unit permits region-selective development of acidic regions in the pattern. The kinetics of polymerization were established to control of the final composition. Moreover, the efficiency of cross-linking and deprotection was studied in thin coating configurations. A major goal was to combine conventional photolithography patterning with assembly-based methods for the heterogeneous integration of nanoparticles into MEMS polymer structures. The results of this research establish polymers that are both structurally definable and photo-addressable. Through the use of two different wavelengths of light, the polymers can be incorporated into MEMS devices and subsequently acid patterned through conventional photolithography. The regions of acidity can then direct the assembly of nanoparticles to the polymer matrix to nanomanufacture multi-functional structures and surfaces. Broader impacts included the training of a Hispanic male PhD student in polymer synthesis and thin film characterization techniques. The student is currently in Germany on a Fulbright fellowship studying how to integrate the polymers synthesized in this study in microfluidic devices. Moreover, the results of this research have been incorporated into an undergraduate course entitled "Smart Materials" taught at the University of South Florida.
