Papers by Author: Paolo Cosoli

Abstract: Transport and surface interactions of proteins in nanopore membranes play a key role in many processes of biomedical importance. Although the use of porous materials provides a large surface-to-volume ratio, the efficiency of the operations is often determined by transport behavior, and this is complicated by the fact that transport paths (i.e., the pores) are frequently of molecular dimensions. Under these conditions, wall effects become significant, with the mobility of molecules being affected by hydrodynamic interactions between protein molecules and the wall. Modeling of transport in pores is normally carried out at the continuum level, making use of such parameters as hindrance coefficients; these in turn are typically estimated using continuum methods applied at the level of individual diffusing particles. In this work we coupled experimental evidences to manyscale molecular simulations for the analysis of hen egg-white lysozyme adsorption/diffusion through a microfabricated silicon membrane, having pores of nanometric size in only one dimension. Our joint efforts allowed us a) to elucidate the specific mechanisms of interaction between the biopolymer and the silicon surface, and b) to derive molecular energetic and structural parameters to be employed in the formulation of a mathematical model of diffusion, thus filling the gap between the nano- and the macroscale.

Abstract: Industrial scraps cannot be reused in an advantageous way, mainly because of their degradation. When possible, rejects are added to the virgin material for new molding, although the amount of recycled block copolymer cannot exceed 15% of moldable material to obtain good final performances. The remaining amount of scraps then follows three different routes: i) employment in very poor applications, ii) land filling, and iii) thermal treatment. For this reason, post industrial rejects constitute a major problem both from the standpoint of the European legislation and policy, and from the economic side where enterprises are concerned. In this work we have applied a multiscale simulation approach to study the nanostructured equilibrium morphology of blends consisting of mainly recycled block copolymers of special interest in the automotive industry. The main goal was the definition of the possible causes leading to incompatibility due to non virgin materials. In particular, starting from atomistic-based simulations we derived a procedure to 1) describe in appropriate fashion the polymer chains in terms of the relevant Gaussian models, and 2) determine the relevant Flory-Huggins interaction parameters. Finally, we coupled mesoscale model with finite elements codes to obtain a quantified structure-property relationship for mechanical modulus and coefficient of thermal expansion.