Pore size profile and thermal degradation of collagen-based porous material used in hemostasis

Hemopatch™ Sealing Hemostat is a NHS-PEG-coated collagen pad and hemostatic agent designed to help stop or limit bleeding during surgery. It is a Baxter product, available on the market, yet no information regarding its manufacturing or structure are made available by the external manufacturers. This thesis presents a quantified characterization of the collagen pad's porosity, as well as an investigation into the pad’s thermal degradation. The collagen scaffold proved to be a highly porous material, with an estimated relative density between 1 and 3 %. It is quite isotropic, but presents a slight fiber preferential direction in the plane parallel to the pad’s surface. Most pores have a diameter superior to 10 μm and present a low interconnectivity. When heated, the collagen pad denatures at ∼ 75 °C, and, above 200 °C, it shrinks isotropically. When it has reached a maximum shrinking, its relative density has increased to ∼ 46 %, which makes it stiffer by almost three orders of magnitude. The pore size also decreases but most pores retain a diameter superior to 5 μm. Finally, by heating the pad with a pre-heated grid, this thesis also demonstrates the possibility to degrade the collagen pad only partially. This offers a possibility to adjust the pad’s structure after its manufacturing in order to improve its hemostatic properties, which could further be explored.