Photoresponsive polymers are smart polymers whose structure and properties can be altered in response to light of suitable wavelength. In the present work, we develop a photoresponsive polymer azo-polyurea (azo-PU) by covalently linking the photo-moiety azobenzene to the main chain of polyurea. Azo-PU undergoes a reversible isomerisation from the more stable trans isomer to the cis isomer on irradiation with 365 nm UV light, and the reverse reaction occurs at 450 nm visible light. The isomerization causes changes in geometry, dipole moment, wettability, viscosity, solubility and spectroscopic properties of the material. The present study is focussed on the property modulations and applications of photoresponsive azo-PU by blending with functional polymers.


First, we illustrate light assisted pattern formation in thin films of azo-PU using self-organization and dewetting, and the ordered (10 nm – 1 μm) patterns were used as templates for protein patterning. Further, an interfacial hydrodynamic model is discussed to explain the dynamics of pattern formation from a fluid mechanical perspective, and process parameters required for ideal templating were determined. The development of visible light responsive polymers by blending azo-PU with polystyrene (PS) is reported, based on the red-shift and electronic transitional overlap observed in these blends. Comparing the properties of azo-PU in solution and solid state shows changes in electronic excitation energy of the transition band, H-bonding interactions and aggregate formation of azo-PU in presence of a polar solvent. Finally, a semiconductive, photoresponsive thin film was developed by blending azo-PU with PEDOT:PSS exhibiting conductivity changes on UV exposure making it a prospective candidate for UV sensors.