Synthesis of a photostrictive azobenzene polymer thread

Photostrictive polymers are a shape memory material that actuates between two mechanical states due to application of different wavelengths of light. Photostrictive materials often exhibit large strains during this process. In this work a novel photostrictive polymer was synthesized using a similar procedure to the synthesis of nylon threads. A monomer containing azobenzene, a photoreactive switch, was synthesized. The novel monomer was polymerized into a material with similar properties to that of nylon where the photoswitch replaces some of the alkyl units created by the adipoyl chloride monomer. This creates a new photostrictive thread alternative to flat sheets for artificial muscle applications. Additionally, the photoactive monomer and the original nylon monomer, adipoyl chloride, were used concurrently to produce a copolymer with varying degrees of the photoactive unit. Utilizing a copolymer methodology allows the innovative thread-like material to be tunable, by varying the amount of photoactive units embedded into the polymer strand. Ratios of the photoswitch unit to adipoyl chloride of 1:5, 1:10, 1:25, and 1:50 were synthesized. The synthesized polymer strands were dissolved in formic acid so that the incorporation of the photoactive units could be measured using Ultra Violet-Visible (UV-Vis) spectroscopy. The absorbance at varying wavelengths was determined and compared to the base polymer, nylon. All azobenzene samples exhibited a direct correlation to an absorption band at 345 nm and the concentration of the photoswitch unit.