Ultrastrong hydrogel adhesives that can carry greater than 50kgs of weight and yet can be rendered reversible. 

The current limit for the strength of reversible and reworkdable dry adhesives is in the range of 10-100 N/m². This range is not enough to carry large weights greater than 50kgs.

The current invention reports ultrastrong hydrogel patches made from poly(hydroxyethylmethacrylate) (PHEMA) that exhibit one order of magnitude higher adhesive strength of up to 892 N/m² in the dry state and yet can be rendered reversible by moisturizing the patch with water to release it effortlessly. The hydrogel system can change its elastic modulus from 200kPa (in the wet state) to a few GPa (in the dry state), which helps in “locking” the patch to the target.

This invention was inspired by the epiphragm of snails, that is by the drying of the mucus that helps lock shells to targets. This PHEMA hydrogel system can change its elastic modulus from 200kPa (in the wet state) to GPa (in the dry state). When the wet gel patch is loaded onto the target, the softened gel conforms to the target and make a good contact. Upon drying, its modulus increases significantly while remaining to be conformally contacted with the target such that it gets “locked” to the rough surface, leading to a high pull-off strength of 223N and 1058N with 0.25 cm² and 2 cm², respectively. When rewet, the patch is softened again, the adhesion stress is released and the patch is peeled off easily.

• The hydrogel system can change its elastic modulus from 200kPa (in the wet state) to a few GPa (in the dry state), which helps in “locking” the patch to the target conformally
• Produces a high pull-off strength of 223N and 1058N with patch area of 0.25 cm² and 2 cm², respectively
• When rewet, the patch is softened, the adhesion stress is released and the patch is peeled off easily, hence is reversible
• Ultrastrong patches that exhibit one order of magnitude higher adhesive strength of up to 892 N/m², comparable or superior than that of the superglue, which is a liquid based adhesive
• Can carry large weights of greater than 50kgs
• The patch can be reusable