Solvent effects on the thermal and mechanical properties of poly(methyl methacrylate) casted from concentrated solutions

The thermal, mechanical, and structural properties of poly(methyl methacrylate) (PMMA) samples casted from solutions of chloroform, toluene, and N , N ‐dimethylformamide (DMF) were investigated by means of differential scanning calorimetry, nanoindentation, and Fourier transform infrared spectroscopy, respectively. The thermal analysis showed that for PMMA prepared from chloroform and toluene solutions the glass transition temperature was quite lower than for bulk PMMA, whereas for PMMA prepared from the DMF solution it was higher. The mechanical analysis showed higher reduced modulus and lower creep effect for PMMA prepared from the DMF solution than for PMMA prepared from the chloroform and toluene solutions. The spectroscopic analysis pointed out the formation of a strong bond between the polymer carbonyl group and the solvent amide group for the PMMA prepared from the DMF solution and a significant distortion of the polymer chain for the PMMA prepared from the chloroform and toluene solutions. Therefore, the observed thermal and mechanical behavior is ascribed to the different hydrogen bonding contributions, the rotation of the end group, and the distortion of the polymer chain.