Effect of solvents on the dynamic viscoelastic behavior of poly(methyl methacrylate) film prepared by solvent casting

Poly(methyl methacrylate) films were prepared by dissolving the polymer in chloroform, toluene and tetrahydrofuran, with identical concentrations of 200 mg/mL, and drop casting the solutions on Teflon surface at room temperature. The thermal, thermomechanical and structural properties have been investigated by differential scanning calorimetry, dynamic mechanical analyzer, and Fourier transform infrared spectroscopy, respectively. The dynamic mechanical behavior of the films has been measured over a temperature range of 30–150 °C, using sinusoidal stress with a frequency of 2 Hz. The samples prepared from tetrahydrofuran showed the highest storage modulus, indicating a higher polymer chain entanglement in that solvent, whereas the samples prepared from chloroform showed the lowest storage modulus. The samples prepared from chloroform, which showed the weakest mechanical properties, also showed the lowest glass transition temperature, which is evidence of the plasticization and solvent retention mechanism of chloroform. The spectroscopic analysis confirmed the solvent-polymer interactions giving rise to the above mentioned effects.