Photofabrication of surface relief grating on films of azobenzene polymer with different dye functionalization

Abstract

Photofabrication of surface relief grating (SRG) on very high-Tg and lower-Tg azobenzene functionalized polymers was investigated. Polymers with different degrees of functionalization were designed and synthesized to understand the chemical and physical intricacies involved at the molecular level in the photofabrication of SRG. The systematic study examined the influence of three important parameters: the degree of azo functionalization, the irradiating light intensity, and the initial film thickness. From the experimental results, we establish that the writing behavior of photofabricated SRG depends on the degree of azo functionalization. The effective critical intensity of the irradiating light was found to be independent of the degree of functionalization. Threshold behavior for the deformation process as a function of the degree of functionalization was established. The observed film thickness dependence of the SRG formation is discussed within the framework of existing fluid mechanics model. The thermal properties of the photofabricated SRG were also investigated.