Quantitative measurement of the polydispersity in the extent of functionalization of glass-forming calix[4]resorcinarenes.
The polydispersity in the degree of functionalization for two calix[4]resorcinarenes was determined by measuring quantitatively their molecular mass distribution with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. A mathematical method for polydisperse materials is described that creates a calibration curve to correct the ion signal intensities in the mass spectrum to give a more reliable molecular mass distribution. Correction is required due to various sample preparation and instrumental effects that may produce a systematic mass bias in the number of oligomers measured. This method employs gravimetric mixtures of analytes with different degrees of functionalization. One calix[4]resorcinarene was found to give accurate molecular mass distributions with little correction, while another, having a very similar molecular structure, was found to exhibit strong over-counting of the oligomers having a high degree of functionalization.
Wallace
W E
WE
Polymers Division, National Institute of Standards and Technology, Gaithersburg, MD 20899-8541, USA. William.Wallace@nist.gov
Flynn
K M
KM
Guttman
C M
CM
VanderHart
D L
DL
Prabhu
V M
VM
De Silva
A
A
Felix
N M
NM
Ober
C K
CK