Dielectric behaviour of polymethacryloyl chloride

Abstract

The dielectric properties of polymers are of great importance from the point of view of their potential use in a number of electronic and optical devices [15]. Dielectric properties of polymers are sensitive to the structure of their molecular chain [6]. These properties are determined by the mobility of the individual groups or of whole parts of macromolecules, reflecting changes in the aggregate state or state of phase. In polymers, an alteration of the acting electric field corresponds to a retarded reaction of the charge displacement. The extent of the displacement depends on the nature of the electric field and of the restoring forces, hindering displacement. The existence of hindering forces acting on bound charges displaced from equilibrium positions by the acting electric field gives polymers the ability to store electrical energy as potential energy. Because viscous or friction-like forces oppose the displacement of charge in the polymer, the charges are unable to follow the changes in the applied electric field immediately. The extent to which they lag behind the field is the measure of friction-type energy losses in polymers. The electrical energy stored per cycle is proportional to the dielectric constant (e') and the energy lost per cycle is proportional to the dielectric loss (e"). Both e' and e" depend on temperature and the frequency of the electric field. In order to elucidate molecular mechanisms, many researchers have carried out dielectric studies on a great number of polymers [6]. The study, reported here was concerned with the dielectric behaviour of polymethacryloyl chloride (PMAC1). The polymer was synthesized as 40 ml of methacryloyl chloride (Fluka) and 40ml of toluene (Riedel de Haen) were distilled on a vacuum line into a dilatometer, containing 160 mg azobisisobutyronitrile (E. Merck). The dilatometer was sealed under vacuum (10-4torr; 1 torr= 1.333 x 102Pa) and placed in a stirred water bath at 60 °C for 4 h. The contents of the dilatometer were then poured slowly in constantly stirred diethyl ether (dry). White precipitates of PMAC1 were separated out and dried under vacuum for 24 h. A tentative reaction for the preparation of PMACi is shown below: