Nanocomposite Polymer Hydrogels Reinforced by Carbon Dots and Hectorite Clay

Herein, two nanoparticles with different dimensions, spherical carbon dots (C-dots) and sheetlike hectorite clay, were used as physical crosslinkers to fabricate C-dots-clay-poly(N-isopropylacrylamide) nanocomposite hydrogels (coded as C-dots-clay-PNIPAm hydrogels). The mechanical properties, fluorescence features and thermal-responsive properties of the C-dots-clay-PNIPAm hydrogels were evaluated. The experimental results indicate that synergistic effects of C-dots and hectorite clay nanoparticles are able to significantly enhance mechanical properties of the hydrogels. The hydrogels can be stretched up to 1730% with strength as high as 250 kPa when the C-dots concentration is 0.1wt% and the clay concentration is 6wt%. The hydrogels exhibit complete self-healing through autonomic reconstruction of crosslinked network a damaged interface. The hydrogels show favorable thermal-responsive properties with the volume phase transition around 34 °C. In addition, the hydrogels are endowed with fluorescence features that are associated with C-dots in the hydrogels. It can be expected that the as-fabricated C-dots-clay-PNIPAm hydrogels are promising for applications in sensors, biomedical carriers and tissue engineering.