3.2. Effect polyol incorporation on metal dispersion
The non-uniform dispersion of MNPs must be due to the heterogeneous density of the small amount of hydroxyl groups belonging to the incorporated H20 poly dendrimer on the CT surface. Incorporation of polyol appears to act as the main dispersing agent of MNP, favoring complete metal entrapping by surrounding OH groups. This must take place through stronger Polyol-HO:Metal interaction that consumes all available OH groups of the inserted dendrimer at the expense of H20@CT surface association. This explains the presence of Polyol:MNP composite scales unstuck on the CT surface (Fig. 1.b ). Similar observations can be made with Ag-modified materials, except the fact that metal salt needles apparently occur in much higher density. This corresponds to a relatively higher amount of residual unreduced Ag salt, i.e. less Ag0 compared to copper-loaded materials. This lower reduction level of Ag+ cations suggests a lower amount of Ag0 atoms. This could explain somehow the paradoxically weaker antibacterial activity of Ag-based materials as compared to their Cu counterparts, given that silver is expected to display higher performance in this regard. A partial explanation resides in the stronger capacity of copper to undergo oxidative processes as compared to silver. The involvement of the OH groups in metal stabilization can be explained by changes in the hydrophilic character and basicity of the host materials. Deeper insights in this regard were achieved through TPD measurements.