Glass Network Interaction with Water

It follows from the fit presented in Fig. 46 that Eb energies for all porous glass samples are about the same value of 33 kJ mol-1. However, for sample B the value of Eh is about 10% less than those for samples A and C. This fact can most likely be explained by the additional chemical treatment of sample B with KOH, which removes the silica gel from the inner surfaces of the pore networks. It is reasonable to assume that the defects generally form at the water interfaces, and only then penetrate into the water layer. Thus, it seems that the KOH treatment decreases the interaction between the water and inner pore surfaces and, consequently, decreases the defect formation energy Eb. 

The role of water in the conformation, the activity and the stability of proteins has been investigated with many experimental and theoretical approaches. Because of its importance it has been coined as the 21 amino acid . There is now sufficient experimental evidence for the fact that dry proteins do not unfold by increased temperature or pressure [21]. Low levels of hydration give rise to a glassy state and the temperature of the glass transition depends on the amount of water as observed for synthetic polymers. Water can therefore be considered as a plasticizer of the protein conformation. Whereas hydrophobic interactions have dominated the interpretation of the data, hydrogen bond networks of water may also play a predominant role in water-mediated interactions [48,49]. 

Moisture is a well-known plasticizer for macromolecules (14). Specifically, water penetrates into an epoxy network and can lower the glass temperature of the resin (15). In this report, moisture has for the first time been utilized as a probe to characterize denslfIcatlon process during epoxy aging. Also, using the same rationale, heavy water diffused Into the epoxy resin Is used to study the Interactions of moisture with the aging polymer by hydrogen-2 (deuterium) NMR spectroscopy. 

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