|Krohn, F.; Neuber, C.; Rössler, E.A.; Schmidt, H.-W.: Organic Glasses of High Glass Transition Temperatures Due To Substitution with Nitrile Groups, Journal of Physical Chemistry B, 123, 10286−93 (2019) -- DOI: 10.1021/acs.jpcb.9b08792|
The glass transition temperature (Tg) of a molecular glass depends on its molar mass. However, the nature of intermolecular interactions also plays a major role in both the glass transition temperature and its glass-forming ability. In this context, we report on novel molecular glasses containing nitrile groups and investigate the influence of this highly polar group on Tg and the glass-forming ability. As reference compounds, we studied the thermal properties of synthesized molecular glasses with C−C-bonded phenyl rings. The molar mass of the studied compounds ranges from 341 to 568 g/mol. Despite their relatively low molar mass, glass transition temperatures from 347 K (74 °C) to 471 K (198 °C) were observed. Most of the compounds possess high Tg/Tmratios between 0.7 and 0.8. By introducing highly interacting nitrile groups, the dependence of the molar mass on Tg could be increased by a factor of 2−3.