1 research outputs found
Characterization of 3‑Aminopropyl Oligosilsesquioxane
The synthesis routes in the production
of polysilsesquioxanes have
largely relied upon <i>in situ</i> formations. This perspective
often leads to polymers in which their basic structures including
molecular weight and functionality are unknown [Lichtenhan, J. D.; et al. Silsesquioxane-siloxane copolymers
from polyhedral silsesquioxanes Macromolecules, 1993, 26, 2141−2142, http://dx.doi.org/10.1021/ma0060a053]. For a better understanding of the polysilsesquioxane properties
and applications, there is a need to develop more techniques to enable
their chemical characterization. An innovative method was developed
to determine the molecular weight distribution (MWD) of an oligosilsesquioxane
synthesized in-house from (3-aminopropyl)Âtriethoxysilane. This method,
which can be applied to other silsesquioxanes, siloxanes, and similar
oligomers and polymers, involved separation using high performance
liquid chromatography (HPLC) and detection using mass spectrometry
(MS) with electrospray ionization (ESI). The novelty of the method
lies on the unique determination of the absolute concentrations of
the individual homologues present in the sample formulation. The use
of absolute concentrations is necessary in estimating the MWD of the
formulation when relative percentage, which is based solely on mass
spectral ion intensities, becomes irrelevant due to the disproportionate
response factors of the homologues. Determination of absolute concentration
requires the use of single-homologue calibration standards. Because
of commercial unavailability, these standards were prepared by efficient
fractionation of the original formulation