Layered shape and swelling behavior of silk sericin/Poly (NIPAm-LMSH) nano composite hydrogels

The silk sericin/Poly(isopropylacrylamide-lithium magnesium silicate hydrate) (SS/Poly(NIPAm-LMSH)) nano composite hydrogels with high swelling ratios and rapid responsibility, via semi-interpenetrating network and in-situ radical polymerization, were prepared by introducing SS with good bio-compatibility and high water absorption into Poly(NIPAm-LMSH) nano composite hydrogel network. The effects of SS content on the pore morphology, swelling behavior, crystal structure, compatibility and stability of the resulting hydrogels were investigated. The results show that the SS/Poly(NIPAm-LMSH) hydrogels after freeze-drying present porous structure with large pore size 20-30 μm and thinner pore walls 1-4 μm. With increasing SS content, the pore shape turns to elongated and layered structure from polyhedral structure. Compared to pure Poly(NIPAm-LMSH) hydrogels in equilibrium swelling state, the addition of SS increases the swelling ratios, belonging to non-Fickian diffusion at the beginning of swelling process, and water was expelled 90% from the hydrogel matrix within 10 min at 37 ℃. The sericin in the hydrogels shows good compatibility and T_g at 141-144 ℃. The maximum thermal decomposition temperature of SS/Poly(NIPAm-LMSH) nanocomposite hydrogels is 365-373 ℃, and the mass remaining ratios increase with the addition of sericin content.