ISSN:
0887-624X
Keywords:
radical polymerization
;
radical copolymerization
;
effect of LiClO4
;
ESR spectrum
;
propagation rate constant
;
termination rate constant
;
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The effect of LiClO4 on the polymerization of di-2-[2-(2-methoxyethoxy)ethoxy]ethyl itaconate (DMEI) with dimethyl 2,2′-azobisisobutyrate (MAIB) was investigated in methyl ethyl ketone (MEK) kinetically and by ESR. The polymerization rate (Rp) at 50°C, where the concentrations of DMEI and MAIB were 1.00 and 5.00 × 10-2 mol/L, increased with increasing [LiClO4]. Marked acceleration was observed at higher [LiClO4]s than 1.0 mol/L. The molecular weight of resulting polymer (ca. 10,000) was relatively insensitive to [LiClO4], indicating occurrence of chain transfer. IR analysis of mixtures of LiClO4/DMEI and LiClO4/poly(DMEI) indicated complexation of LiClO4 with DMEI and its polymer. The rate constants of propagation (kp) and termination (kt) were determined by ESR. kp (1.7-10.5 L/mol s at 50°C) increased with [LiClO4]. kt (5.2-1.0 × 104 L/mol s at 50°C) showed remarkable decrease at higher [LiClO4]s than 1.0 mol/L. Rp of polymerization of equimolar complex of LiClO4/DMEI with MAIB at 50°C in MEK was expressed by Rp = k[MAIB]0.5[DMEI]2.4. kp increased and kt decreased with [DMEI]. The activation energies of overall polymerization, propagation and termination were estimated to be 34.5, 8.0, and 59.4 kJ/mol. Copolymerization of DMEI with styrene was also profoundly affected by the presence of LiClO4. Such large effects of LiClO4 on the homo- and copolymerization of DMEI are explicable in term of association of LiClO4-complexed DMEI monomers. © 1997 John Wiley & Sons, Inc.
Additional Material:
11 Ill.
Type of Medium:
Electronic Resource
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