Experiments were conducted to evaluate the effect of polydisperse tethered chains on the toughness of an impenetrable interface. The results indicate that tethered chains improved the toughness of such interfaces - an improvement that we attribute to an interaction between the tethered chains and the matrix free chains. An increase in the tethered chain length relative to the free chain length, plus the natural polydispersity of the tethered chains, appears to underlie this beneficial interaction.