Multistimuli Responsive Polymer Nanoparticles On the basis of the Amphiphilic Azobenzene-Contained Hyperbranched Poly(ether amine) (hPEA-AZO)

We here reported the multistimuli responsive behavior of polymer nanoparticles, which was formed through direct dispersion of the amphiphilic azobenzene-contained hyperbranched poly(ether amine) (hPEA AZO) in water A series of hPEA-AZO were synthesized by introduction of azobenzene moieties into the periphery of hyperbranched poly(ether amine) (hPEA), which was developed by our group recently The obtained polymer nanoparticles of hPEA AZO which were revealed by dynamic light scattering (DLS) and transmission electron microscopy (TEM), exhibited the sharp stimuli-response to temperature, pH, and ionic strength with tunable cloud point (CP) from 25 to 100 degrees C CP of the obtained hPEA AZO nanoparticles in aqueous solution decreased with the increase of azobenzene content, pH value and ionic strength, and represented a linear relationship with the azobenzene content and ionic strength The hPEA-AZO nanoparticles also showed a light controlled CP and size After UV irradiation (365 nm), we observed lower value of CF and larger size for hPEA-AZO nanoparticles The CF difference of hPEA AZO nanoparucles in aqueous solution between before (CPT, trans form) and after (CPC, cis from) UV irradiation (365 nm) increased linearly upon the azobenzene content up to 5 degrees C