Structural characterization of pulsed laser deposited poly(methylmethacrylate) thin films

Cross-linking content and polymerization degree of poly(methylmethacrylate) PMMA thin films have been investigated by means of Fourier transform infrared and micro-Raman spectroscopic techniques. The samples were deposited by means of pulsed laser ablation of a PMMA target at room temperature. The laser fluence was varied from 0.5 J/cm(2) up to 4 J/cm(2). Experimental results show that it is possible to deposit PMMA thin films with a very low monomer content (smaller than 3%) and to modulate the cross-linking occurrence upon tuning the laser fluence. Moreover, the effect of the post-deposition thermal treatment on the polymerization degree has been exploited. Then, we estimated the value of the polymerization enthalpy, which is comparable to the value at which the complete conversion of monomers in polymer is reached.