Hardening of smooth pulsed laser deposited PMMA films by heating

Abstract

Smooth poly(methyl methacrylate) (PMMA) films without any droplets were pulsed laser deposited at a wavelength of 248 nm and a laser fluence of 125 mJ/cm 2 . After deposition at room temperature, the films possess low universal hardness of only 3 N/mm 2 . Thermal treatments up to 200°C, either during deposition or afterwards, lead to film hardening up to values of 200 N/mm 2 . Using a combination of complementary methods, two main mechanisms could be made responsible for this temperature induced hardening effect well above the glass transition temperature of 102°C. The first process is induced by the evaporation of chain fragments and low molecular mass material, which are present in the film due to the ablation process, leading to an increase of the average molecular mass and thus to hardening. The second mechanism can be seen in partial cross-linking of the polymer film as soon as chain scission occurs at higher temperatures and the mobility and reactivity of the polymer material is high enough.

Confinement of phonon propagation in laser deposited tungsten/polycarbonate multilayers

“…Independent of the laser fluence used during deposition, all curves show the absorption maxima typical for the different bondings in PC [29]. The small deviations from bulk PC concerning the intensity of the peaks are explainable by the process of incubation at the target [30].…”

MoS2/Polymer Heterostructures Enabling Stable Resistive Switching and Multistate Randomness

“…We note that the temperature of the substrate during the transfer plays a crucial role for the subsequent polymerization. At temperatures above 170 °C, continuous polymer layers were formed in between MoS 2 layers during the transfer process, while there were no obvious polymer residues observed when the transfer was conducted at 150 °C (see Figure S5, Supporting Information) [ 14 ] We speculate that the PMMA wetting on the sputter‐grown MoS 2 facilitates the formation of polymer layers. This is likely caused by PMMA adsorption at the grain boundaries of the nano‐sized crystalline domains, similar to previously reported absorption of molecules at the grain boundaries of MoS 2 .…”

Applications of Compact Laser-Driven EUV/XUV Plasma Sources

“…In Figure 12, a measured NEXAFS spectrum of Polyimide is displayed, demonstrating the possibilities of this principle. Other applications are the determination of chemical changes in UV/EUV irradiated polymers [41] or the investigation of the transient electronic structure of PCMO.…”