Dependence of ultraviolet nanosecond laser polymer ablation on polymer molecular weight: Poly(methyl methacrylate) at 248 nm

摘要: We rely on a methodology demonstrated previously for assessing the temperature evolution and polymer viscosity changes in 248nm irradiation of poly(methyl methacrylate)s (PMMAs) with molecular weights (Mw) ranging from 2.5to996kDa. Briefly, this [G. Bounos et al., J. Appl. Phys. 98, 084317 (2005)] relies monitoring formation aryl products doped iodonaphthalene or iodophenanthrene. The results demonstrate that higher temperatures are attained increasing Mw. surface at corresponding ablation thresholds estimated to be ∼850–900K Mw⩾120kDa vs ∼600K 2.5kDa PMMA. In addition, all Mw’s, melting is (viscosity values ≈101Pas), but it lasts longer high Mw PMMAs. ascribe these differences fact low PMMAs dissociate efficiently desorbing monomers/oligomers, thereby resulting more efficient energy removal. Even so, threshold h...