(327a) Engineering Photoresponsive "Smart" Materials Using Pamam Dendrimer Chemistry

A photoresponsive ?smart? material was made by incorporating a photochromic azobenzene compound into a side chained dendritic polyester. Upon irradiation at a specific wavelength of light, the azobenzene compound undergoes changes in its overall structure and properties that can be used to produce physical property changes in the polymer. The development of smart materials that can reversibly change shape or properties by simple photoirradiation, could allow for components that are lighter and capable of responding faster than current adaptive materials. One important factor is that the material must be strong enough to be formed and retain physical strength. This requires a bulkier azobenzene, which poses a difficult dilemma. The nitrogen double bond on the azobenzene isomerizes from its stable trans to its less stable cis conformation during photoirradiation. Adding bulky substituents to the aromatic group of the azobenzenes can hinder this process and reduce the photoresponsiveness of the material. Polyamidoamine (PAMAM) dendrimer wedges allow a large unit to be readily added to a single linear chain. The resulting functionalized macromolecule was reacted with an azobenzene to form a photoresponsive side chain dendritic polyester (SCDPE). In this work PAMAM dendrimers were incorporated into photoresponsive polymers with the goal of increasing stability without losing the photoefficiency of the polymer. Further work, will focus on enhancing the PAMAM dendrimer design by implementing additional photoresponsive groups onto the peripherals of the dendrimer wedges. The incorporation of these dendrimer wedges to the linear polymer will be used to increase the photoefficiency of the polymer. Thin films of the polymer will be cast onto a flexible substrate that will aid in converting the light energy provided upon irradiation into a mechanical response, resulting in a reversible deformation of the ?smart? material.