Thermoresponsive nanocomposite hydrogels with improved properties based on poly(N-vinylcaprolactam)

[Display omitted] •Poly(N-vinylcaprolactam) hydrogels by a photochemical method using a divinylacetal crosslinker.•Nanogels as fillers (0.3 wt%) of hydrogels increase Young modulus up to 278 %.•Nanoclays as fillers (1 wt%) of hydrogels increase Young modulus up to 128 %.•Reversible shrinkage (50 %) by heating from 25 °C to 37 °C while modulus increase 2.1 times.•Poly(N-vinylcaprolactam) hydrogels (4% crosslinker) stable to acid hydrolysis at pH 5 up to 15 days. In this work poly(N-vinylcaprolactam)(PNVCL) hydrogels were filled with nanogels as soft fillers and with nanoclays as hard fillers to yield reinforced materials. They were prepared by radical photopolymerization with nanoparticle loads of up to 1 wt%, adding a chemical crosslinker. The effect of the fillers and crosslinker in the thermal, swelling and mechanical properties is described. Results show that Young’s moduli of swelled hydrogels are between 170–4500 KPa by mechanical compression tests, the higher values obtained by using nanogel fillers. On the other side the thermal shrinkage of the hydrogels by heating from room temperature to 37 °C is up to 50 %, while the Young modulus increases 2.1 times. The title nanocomposite hydrogels show potential application as responsive biomaterials.