*3.2. Thermal Analysis*

Thermogravimetric analysis of the polymers carried out under ambient atmosphere revealed an onset of thermal decomposition at about 380 and 400 ◦C respectively for PPM containing 13.4% mol/mol and 6.1% mol/mol of repeat units with alkoxy side chains, respectively, while the maximum decomposition rates were observed at 482 ◦C (for 13.4%) and 508 ◦C for (for 6.1%), compared to 510–515 ◦C for PPM itself [5,18].

Differential scanning calorimetry (DSC) performed with the copolymers revealed in each case only a single glass transition temperature (Table 2). The glass transition temperature (Tg) of the copolymers decreases as the fraction of the octyloxy side chains along the polymeric backbone increases. The pure PPM of *M*n = 2400 g mol−<sup>1</sup> features Tg≈ 55 ◦C [2] while the PPM derivative containing 6.1% and 13.4% mol/mol of octyloxy side-chains exhibited Tg values of 48 and 31 ◦C, respectively (Table 2). This is likely due to the relative difference in mobility of the polymer chains, whose motion is progressively enhanced with the increase of the concentration of octyloxy substituents, leading to the corresponding decrease of Tg [20]. Moreover, the lack of any thermal transition beyond the glass transition temperature indicates that the copolymers are amorphous like PPM itself [6].

**Table 2.** Glass transition


fference between the

temperature

 T applied

temperatures

 (Tg) and the di

