Photoswitchable Polysiloxane Self-Assembled Monolayer

Abstract

An azobenzene-spaced polysiloxane polymer was synthesized and characterized, and its isomerization was studied in solution and as a thin film by UV-Vis spectroscopy. The self-assembled monolayers (SAMs) on the silicon surface permit reversible molecular photoswitching. Contact angle results showed the hydrophilic nature of the trans-isomer compared to the cis-isomer. This was supported by the dipole moment calculation from density functional theory (DFT), which showed a higher value for the trans-isomer, thereby confirming its hydrophilic nature. The AFM study revealed polymeric brush-like structure on the silicon surface and confirmed its isomerization upon exposure to UV-Vis light.