A: Butyl acrylate (BA) contributes to the formation of graft copolymers by reacting with the radicals generated from triethylborane (TEB). It forms a copolymer with vinyl butyl ether (VBE) in an alternating structure, which is then grafted onto the collagen macromolecules. This grafting process enhances the mechanical stability and biocompatibility of the resulting copolymer.