Thermal Studies of Metal Poly (Styrene-co-Ethyl Methacrylates) Part XVIII

Abstract

Metal poly(styrene-co-ethyl methacrylates) copolymers were obtained by radical polymerization with benzoyl peroxide (BPO) and azodiisobutironitrile (AIBN). The monomers were cocondensed with the metals: Pd, Cu, Ag, Au. Zn, Cd, Ga, In, Ge, Sn, Sb and Bi at 77 K. The metals were evaporated toproduce atoms and with the monomers they can generate a matrix on the reactor walls at low temperature. During the warm up process, metal-co-monomer colliods can be obtained. The colloids were polymrized with BPO at 65°C for 3.5h and with AIBN at 65°C for 3.4h. From different initiator conentrations (0.1, 0.2, 0.5 and 1.0 mol%) were used. The yields are fairly low and the viscosimetric molecular weight range from 104–105 g/mol. The higher Mv are Cd, Pd, Ag and Au-poly(styrene-co-ethyl methacrylates) for AIBN series and Ag, Pd, Au and Zn-SEMA for BPO series. The thermal stabilities of these metal polymers have been studied by thermogravimetry (TG) between 25 and 550°C under nitrogen flow. The decomposition temperatures were obtained from the first deverative from TG curve. The kinetic parameters of the thermal decomposition were determined by the Arrhenius equation. All these copolymers degrade in a single step process around 300°C. The kinetic data thus obtained show the thermostabilities decrease in the order: In-SEMA > Bi-SEMA > Sn-SEMA > Ga-SEMA > Zn-SEMA > Au-SEMA > Cd-SEMA > Pd-SEMA > Ge-SEMA > Cu-SEMA > Sb-SEMA > Ag-SEMA for AIBN and Cd-SEMA > Sn-SEMA > Pd-SEMA > Ag-SEMA > Bi-SEMA > Ge-SEMA > Au-SEMA > Zn-SEMA > Sb-SEMA > In-SEMA > Cu-SEMA > Ga-SEMA for BPO. The thermal stability is depending upon the metal incoroporated in the polymer matrix. The decomposition reaction order is zero either for AIBN or BPO series of metal copolymers. The pre-exponential factor and the activation energy of the decomposition reaction for all the copolymers have been determined.