The review presents recent developments in the area of polymeric systems modified with bulky derivatives of tris(trimethylsilyl)methane (T_Si). These nonpolar and chemically stable moieties provide a steric hindrance effect comparable to that of octahedral silsesquioxanes and severely restrict the movement of polymer segments. It leads to a significant increase of glass transition temperature and a tremendous improvement of the thermostability of polymeric systems. The studies were focused on the physiochemical properties of simple, linear polymers and more elaborate hybrid systems of specific physiochemical properties. Several areas of possible application of these materials are outlined.