Effect of previous thermal history on physical aging of amorphous poly (ethylene terephthalate)

Physical aging of amorphous PET, at aging temperatures (T_a) of 40 and 60°C and different aging times (t_a), has been studied by DSC using two kinds of samples with different thermal history: Liquid-Nitrogen-Quenched samples (LNQ) and DSC cooled samples at a controlled cooling rate of 60 K/min (CC). At T_a = 40°C, a sub-T_g peak appears in LNQ samples but is not clearly observed in the CC samples. At T_g = 60°C, a superposed peak to T_g is observed in both kinds of samples. This different behaviour can be explained considering the distribution of relaxation times in the polymer.     

Site-selective multi-emitter gold-silver metallopolymers: A novel class of self-assembled materials

New luminescent heterometallopolymers [(Au-C₆F₅)_m(AgOSO₂CF₃)_n (PVP)] with different Au:Ag molar ratios were synthesized. The luminescent emissions of these polymers are strongly dependent on the temperature, excitation wavelengths, and the Au(I):Ag(I) molar ratio. The incorporation of a precise amount of Ag(I) atoms in the backbone of [(Au-C₆F₅)_m(PVP)] metallopolymer allows a controlled tuning of the emission energy in the green-blue range.