[(3-Methacryloxy)propyl]silsesquioxanes (MSSO) were prepared from the hydrolytic condensation of [(3-methacryloxy)propyl]trimethoxysilane (MPMS) in the presence of an acid catalyst (HCOOH). The proposed MSSO structures were characterized with Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) (1H, 13C and 29Si), and were assigned by ultraviolet laser matrix-assisted desorption/ionization time-of-flight mass spectrometry (UV-MALDI-TOF MS). The large organic group connected to silicon was simplified for the quantum chemical calculation (QCC), and the correlation of the calculated total energies (ET) before and after simplification was analyzed by multiple linear regression, verifying no significant influence on the final conclusions of the research of structural formulas by a correlation coefficient (r). The geometric parameters (Si-O bond length and Si-O-Si, O-Si-O bond angles) and ET of the simplified MSSO were calculated by QCC to determine the relative stability of various MSSO structures. The structural geometry (silicon ring), the fraction of intramolecular cycles (f) and the number of the silicon rings (F) were also employed to qualitatively determine the relative stability. The results of the calculation showed that almost all of the cage structures had a lower ET than the isomeric ladder structures; therefore, most MSSO structures are of the cage type.

Structure of POSS with large organic group characterized by UV-MALDI-TOF mass spectrometry and quantum chemical calculation

244th National Meeting (2012)

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