Dynamics of Water Absorption in Polymer Skin Adhesives

Skin adhesives are used to attach medical devices to the body and are required to adhere to the skin also during challenging conditions such as exposure to moisture and sweat. In order to maintain good skin-adhesive contact in these situations, the adhesives should be able to absorb water and remove fluids from the skin-adhesive interface. Consequently, the water absorption properties and distribution of water in the adhesives influence the overall adhesive properties. Understanding how the material composition impacts the absorption and distribution of water in these adhesives is required for rational formulation of skin adhesives. Here, we probe the dynamic water absorption in different skin adhesives using time-resolved impedance measurements and gravimetric analysis. Skin adhesive formulations consisting of soft, hydrophobic polymers providing stickiness, rigid block copolymers enhancing the structure, and hydrogel particles allowing for water uptake were designed. The hydrogel particle content and polymer matrix rigidity were varied, and the adhesives were systematically investigated to link the material composition and water absorption functionality.