Interpretation of the chain structures of PMMAs, PANs and PAAms obtained by using Ce(IV) and KMnO4 in combination with NTA and DTPA as initiator systems by FTIR spectroscopic analysis

Polyacrylamides (PAAms), polyacrylonitriles (PANs) and poly(methyl methacry late)s (PMMAs) were synthesized by using Ce(NH4)(2)(NO3)(6), Ce(SO4)(2). 4H (2)O and KMnO4 in combination with nitrilotriacetic acid (NTA) and diethyle netriamine pentaacetic acid (DTPA), which have strong chelating properties, as redox initiators. Polymerizations were carried out in the aqueous acidi c solutions at 25 degrees C and 55 degrees C in the presence of air. The ch ain structures of the resulting products were studied by Fourier-transform infrared (FTIR) spectroscopic measurements. From the comparison of the spec troscopic results with gravimetric and viscometric data it was concluded th at both the differences between the solubility behaviour in aqueous solutio ns of MMA, AN, AAm and their polymers, and catalyst-activator-monomer combi nations were important parameters effecting the polymerization mechanisms, conversions and the structures of the polymers. The FTIR and viscosity resu lts indicated that PAAms obtained in our experimental conditions formed cro sslinked structures with sulphated complexes of Ce(III) and MnSO4 produced by the redox reactions between catalysts (MnO4- and Ce(IV)), NTA and AAm. F urther, it was observed that PAN chains were terminated by hydrated and sul phated complexes of Ce(III) while the termination of PMMA radicals took pla ce by primary radicals because PMMAs were formed by emulsion polymerization kinetics. (C) 1999 Elsevier Science Ltd. All rights reserved.