Abstract:

The PNIPAM/PAphe interpenetrating nanogels which were responsive to temperature and pH were synthesized. The chemical structure, morphology, particle size and dispersity, temperature-and pH-response, structural color tunability, photonic crystal self-assembly, and sol-gel transition behavior of the interpenetrating nanogels were studied in detail by infrared spectroscopy, scanning electron microscopy （SEM）, dynamic light scattering, and optical fiber spectrometry. According to the infrared spectrum and SEM image, the effective interpenetration and good monodispersity of the two networks were confirmed. The analysis of particle size and polydispersity index （PDI） indicated that, with the increase of PAphe content, the particle size of the interpenetrating nanogels correspondingly increased, but the monodispersity remained good. The temperature-and pH-sensitivity experiments proved the responsiveness of the interpenetrating nanogels, which showed that the particle size was significantly decreased when the temperature was increased or the pH value was decreased. Combined with the optical fiber spectrum, it was further found that the interpenetrating nanogel could achieve controllable structural colors by adjusting the particle size. More importantly, they possessed the ability of transition from sol to gel above T_p （32 ℃） by the method of test tube inversion. These characteristics showed their potential applications in highly controllable optical materials and the biomedical field.

Key words: interpenetrating nanogel, dual-responsive, gelation, structural color