Microspheres based on funcionalized polystyrene are used as supports for immunological reactions. New styrene/Bocaminostyrene (St/BocAmSt) copolymers and the corresponding styrene-aminostyrene (St/AmSt) copolymers obtained as microspheres under dispersion polymerization conditions and successive deblocking reaction respectively, were characterized by thermogravimetry (TG) and differential scanning calorimetry (DSC). Thermal stability was found to be dependent on copolymer molecular weight and composition. The St/AmSt copolymers were more stable than St/BocAmSt copolymers and showed a direct relationship with AmSt content. Glass transition temperature as a function of copolymer composition obeyed the Fox equation in good approximation. For low molecular weight copolymers the glass transition temperature was between 91 degrees C [T-g poly(styrene)] and 151 degrees C [T-g poly(Boc-aminostyrene).