Study on thermal degradation mechanisms of comb polyacrylates containing long fluorocarbon side chains by TG/FTIR

Abstract

Thermal degradation of two series of polyacrylates containing long fluorocarbon chains [abbr.: PF n A (HCF 2 (CF 2 ) n-1 -CH 2 O-C(=O)-, n = 4, 6, 8, 10) and abbr.: PFF n EA (CF 3 (CF 2 ) n-1 -CH 2 CH 2 -O-C(=O)-, n = 6, 8, 10)] was investigated by TG /FTIR. Thermal degradation behavior of polymers changed depending on the type of tie groups, which link the fluorocarbon chains to the main chain, and also on the length of fluorocarbon chains. It was clarified that the apparent activation energies (ΔE α ) of PF n A series obtained by Ozawa's method varied in the order of PF 4 A > PF 6 A > PF 8 A > PF 10 A, while those of PFF n EA series having tie group of -CH 2 -CH 2 -O-C(=O)- were almost constant. The results for PF n A series (tie group: -CH 2 -O-C(=O)-) are attributable to the shield effect of long fluorocarbon chains on the back-biting reaction in the thermal degradation of comb polymers rather than the change of C-C bond dissociation energy in the main chain. It was found that TG curves of PFF n EA series were shifted to the lower temperature region than those of PF n A. This result can be attributable to the scission of side groups followed by the evaporation of fluorocarbon compounds and carbon dioxide.