Crystallization hydrophilic glasses

On evaporation the solvent often creeps up the walls of a glass vessel, because the silicate OH-groups make glass hydrophilic. Therefore nucleation occurs outside the solution this never gives good crystals and can be avoided by using polypropylene or Teflon vessels. 

Differential scanning calorimetry (DSC) is a suitable technique to monitor temperature-depen-dent enthalpic changes in a system related to phase transition. It is well known that PDMS polymer shows a glass transition temperature at about -120°C, and also phase transitions of crystallization and melting. Solid state H-NMR [4] revealed a marked shift in its Tg, to about 0°C, when a PDMS polymer is adsorbed strongly on a silica surface. In this study we investigated the use of DSC to monitor the mobility of the PDMS chains on hydrophilic and silylated silica surfaces. 

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