Melt crystallization kinetics of polyhedral oligomeric silsesquioxane under non-isothermal conditions

• T8 POSS structures have similar melt enthalpies.
• The electronegative atom in POSS pendent group changes the temperature of melting/crystallization.
• The melt crystallization of the POSS structures depends on the symmetry of the cubic structure.
• The self-assembly phenomenon of POSS structures is closely related to its symmetry and type of pendant group.

Melt crystallization of polyhedral oligomeric silsesquioxane (POSS) was studied by differential scanning calorimeter (DSC), X-ray diffraction (XRD), Fourier transformed infra-red spectroscopy (FTIR) and scanning electron microscopy (SEM). The SEM analysis showed that POSS samples are aggregated in micrometric size. Additionally, FTIR spectra confirmed intermolecular interactions among carbonyl groups. All samples showed that the Ozawa exponent ranged from 1 to 2.6 and the Ozawa crystallization rate constant was found to decrease with increasing temperature and reduction of average X(T). This suggests that these POSS crystallized slower as the temperature increased. The ∆EX(T) values for isobutyl POSS increased monotonically until X(T) = 0.4, and for the methacryl isobutyl POSS the ∆EX(T) values decreased. After this point ∆EX(T) showed similar values for both POSS samples. The presence of the methacryl radical in POSS cages interfered in the crystallization process due to the hysteric hindrance among POSS–POSS cages.