Physical and chemical control of interface stability in porous si–eumelanin hybrids

The organic/inorganic interface in thin nanosized porous structures has a key role in determining the final properties of the composite materials. By using the porous silicon/eumelanin hybrids as a case study, the role of this interface was investigated by experimental and computational methods. Our results show that an increased polymer density close to the hybrid interface strongly modifies the diffusion of the chemical species within the polymer molecule, affecting then the oxidation level of the pores inner Si surface. We observed a greater stability induced by increased pore diameter, a behavior that with computational and chemical arguments we attributed to a modified diffusion of the hydrogen peroxide towards the Si/eumelanin interface. Our results show that the overall behavior of a polymer when inserted in a tiny nanoscale structure must be taken into account for a correct understanding and control of the hybrids properties, and that the formation of the interface alone may not be sufficient.