End groups in anionically polymerized standard poly(methyl
methacrylate)s (PMMAs) in
the range of number average molecular weight
(M
n) = 2.0 × 104 to 1.3 ×
106 with narrow molecular
weight distribution were determined by pyrolysis−gas chromatography
(Py-GC). The characteristic
fragments reflecting the end groups on the pyrogram of the PMMAs were
identified by comparison with
those of a radically polymerized PMMA together with the mass spectra of
the characteristic peaks on the
resulting pyrograms taken by a gas chromatograph−mass spectrometer
(GC-MS) system. Concentrations
of the end groups determined from their relative peak intensities were
interpreted in terms of M
n and
then compared with their reference values from the manufactures and
those estimated by 1H-NMR. By
this method, direct determination of the end groups was possible even
for PMMA with M
n ≑ 106
without
using any standard polymer samples.
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