Preparation and controlled properties of temperature/photo dual sensitive polymers by facile Ugi reaction

In this investigation, we described a facile preparation of temperature/photo dual sensitive polymers (PGABs) by Ugi four-component polymerization (Ugi-4CP) at room temperature in “one-pot” method using glutaraldehyde, 4-amido-azobenzene, t-butyl isocyanide and carboxyl-end-capped polyethylene glycols (S-PEG) as monomers. PGABs were found to be reversibly sensitive to the temperature in salt solution, and their lower critical solution temperatures (LCST) can be tuned to the range of 17.2–68.4 °C by changing the structure of PGABs, sort and concentration of salt. The configuration transition of PGABs between cis-form and trans-form was reversibly induced by the alternating radiation at 365 and 254 nm. The rate and conversion of isomerization showed a remarkable dependence on the chemical structure of PGAB. By the photosensitivity, the LCST of PGAB-800 is further regulated in 1.0 °C change because of the hydrophilicity difference of cis-trans-azobenzene moiety. Through the combination of the thermosensitivity and photosensitivity, the particles of PGABs with nano/μm dimension were successfully controlled by the light radiation and temperature change.