John A Lawrence III
47 - Photo-disruption of charged poly(thiophene) layer-by-layer films
Conjugated polymers (CPs) have been extensively investigated in the past few decades due to their attractive opto-electronic properties. These materials have become the focus of research in the growing field of organic electronics because of their conductive nature and the relative ease of their modification using organic synthesis. Poly(thiophene) (PT) and its derivatives represent an important class of CPs that form some of the most environmentally and thermally stable materials used as electrical conductors, polymer LEDs, antistatic coatings, and sensors. However, poly(thiophene) is intrinsically insoluble. Thus, finding novel ways to process and assemble PT derivatives into thin film devices in order to exploit the polymer€s electronic properties is of considerable interest. By using a simple dipping technique, poly(electrolyte) multilayer (PEM) films containing PT with charged moieties can be fabricated by layer-by-layer (LbL) self-assembly. LbL involves the sequential adsorption of poly(anions) and poly(cations) on a charged surface such as plasma-cleaned quartz slides. This method provides easy control over thickness, and charged moieties lend themselves to aqueous processing. By including stimuli-responsive groups in the polymer structure, the application of stimuli such as pH, temperature, and light can be used to change the solubility of the LbL films by disrupting the electrostatic interactions. The aim of our research is to incorporate the photo-reactive o-nitrobenzyl ester functional group into cationic and anionic PT derivatives in PEM films assembled using LbL self-assembly. Integrating a photo-responsive moiety into the PT derivative allows for light to be used to disrupt the electrostatic interactions in the film, resulting in solubility. The fabrication of these photo-responsive PT films is sought after in hopes of creating an organic semiconductor that is its own photoresist, meaning it is amenable to patterning using photochemical processes such as photolithography.