Pg. Brown et K. Fujimori, A MECHANISTIC STUDY OF THE RADICAL COPOLYMERIZATION OF P-METHOXYSTYRENE WITH CITRACONIC ANHYDRIDE VIA C-13 NMR-SPECTROSCOPY, Die Makromolekulare Chemie, 194(7), 1993, pp. 2001-2015
The composition and monomer unit sequence distribution of copolymers o
f p-methoxystyrene (p-MST) with citraconic anhydride (CA) prepared in
methyl ethyl ketone (MEK) at 50,0 +/- 0,1-degrees-C were determined ov
er a range of comonomer feed mole fractions using C-13 NMR spectroscop
y. The monomer units in these copolymers were found to display an incr
easingly strong tendency to alternate as the mole fraction of CA in th
e feed increases. The existence of a 1 : 1 charge-transfer complex for
med between p-MST and CA in the feed was confirmed via UV spectroscopy
and the equilibrium constant for complex formation was determined. Th
e terminal, penultimate and complex-participation models were tested f
or applicability to the mechanism of copolymerisation for this comonom
er system. On the basis of copolymer composition data, the penultimate
and complex-participation models were found to provide each an adequa
te description of the mechanism of copolymerisation in the comonomer s
ystem via non-linear least squares methods. The inadequacies of the te
rminal and penultimate models in describing the copolymers were expose
d more explicitly through an analysis of their comonomer unit sequence
distributions using reactivity ratio related test functions.