Molecular Structure Analysis of Aminophenyl Silsesquioxane (Preprint)
Abstract
The molecular structures of aminophenyl substituted silsesquioxanes, prepared by two different approaches, have been investigated using 29Si NMR spectroscopy. Aminophenyl silsesquioxane prepared by nitration/reduction of octaphenyl POSS(Registered), exhibits broad resonances in the 29Si NMR spectrum, whereas aminophenyl silsesquioxanes prepared directly from aminophenyltrimethoxysilane exhibit very narrow line widths. Wide-angle X-ray diffraction of the products from the direct synthesis show a diffraction peak with a d-spacing value similar to the 101 hkl reflection peak of the rhombohedral lattice seen in several other crystalline POSS(Registered) octamers, whereas the products from the nitration/reduction exhibit no diffraction peaks. Our analysis suggests that aminophenyl silsesquioxane prepared by the nitration/reduction of octaphenyl POSS(Registered) no longer retains the Si-O structure of the starting octaphenyl POSS(Registered), while the aminophenyl silsesquioxanes prepared by the direct synthesis have significant Si-O cage structure. Thermogravimetric analysis on both products indicates that the aminophenyl silsesquioxanes from the direct synthesis have better thermal and thermo-oxidative stability (TOS). Furthermore, this improved thermal stability is extended to highly crosslinked resins prepared from the phenylethynyl phthalimide derivatives of the aminophenyl silsesquioxanes. The thermal analysis suggests that the discrete Si-O frameworks found in POSS(Registered) monomers play an important role in maximizing the thermal and thermal-oxidative stability of the materials in which they are incorporated.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 31, 2006
- Accession Number
- ADA467753
Entities
People
- Andre Lee
- Joseph J. Schwab
- Timothy S. Haddad
- Yi Zhong An
Organizations
- Michigan State University