Evaluation of Local Mechanical and Chemical Properties via AFM as a Tool for Understanding the Formation Mechanism of Pulsed UV Laser-Nanoinduced Patterns on Azo-Naphthalene-Based Polyimide Films

Abstract

Aromatic polyimides containing side azo-naphthalene groups have been investigated regarding their capacity of generating surface relief gratings (SRGs) under pulsed UV laser irradiation through phase masks, using different fluencies and pulse numbers. The process of the material photo-fluidization and the supramolecular re-organization of the surface were investigated using atomic force microscopy (AFM). At first, an AFM nanoscale topographical analysis of the induced SRGs was performed in terms of morphology and tridimensional amplitude, spatial, hybrid, and functional parameters. Afterward, a nanomechanical characterization of SRGs using an advanced method, namely, AFM PinPoint mode, was performed, where the quantitative nanomechanical properties (i.e., modulus, adhesion, deformation) of the nanostructured azo-polyimide surfaces were acquired with a highly correlated topographic registration. This method proved to be very effective in understanding the formation mechanism of the surface modulations during pulsed UV laser irradiation. Additionally to AFM investigations, confocal Raman measurements and molecular simulations were performed to provide information about structured azo-polyimide chemical composition and macromolecular conformation induced by laser irradiation.

Improvement of thermo‐mechanical and fatigue crack growth resistance of tire sidewall compound by introducing syndiotactic polybutadiene

“…The higher positive values of the kurtosis (S k > 3) also suggest leptokurtic surfaces. 30 In this study, scanned height ranging from (À) 100 to 300 nm for reference, qualitatively imply a rougher surface for reference. 31 For V21, V22 & V72 scanned heights ranges from (À) 150 to 200 nm, and for V72 it was again (À) 100 to 300 nm.…”

“…The use of these two 3D topographic parameters allowed us to measure the departure from a Gaussian distribution of surface heights, emphasizing on one hand the degree of symmetry of the surface heights reported to the mean plane ( S sk ), and on another hand the spread of the newly created structures in relation with the whole surface morphology ( S k ). The higher positive values of the kurtosis ( S k > 3) also suggest leptokurtic surfaces 30 …”

Dynamic self-stabilization in the electronic and nanomechanical properties of an organic polymer semiconductor

“…The microscale topography, stiffness, adhesion, and elastic modulus of the stabilized film were acquired using Park System’s PinPoint Nanomechanical measurement mode on an NX20 AFM with a cantilever tip radius of 10 nm. The technique extracts the various nanomechanical properties using the captured force curves which map the interaction between the AFM tip and the sample surface on approach and on retraction 58 – 62 . The films have a smooth texture, with the average modulus quantified to be around 2 GPa.…”

New Strategy for Inducing Surface Anisotropy in Polyimide Films for Nematics Orientation in Display Applications

“…The minimized cells (10 −4 kcal/mol energy convergence) were subjected to NPT dynamics (conserved amount of substance (N), pressure (P) and temperature (T)) at p = 1 atm, T = 298 K, using a Berendsen thermostat and barostat, for 1 ns. The stable values for the temperature and density indicated the reach to the equilibrium [34]. Another NVT dynamic (conserved amount of substance (N), volume (V), and temperature (T)) for 1 ns provides the elimination of every possible unfavorable interaction from the system.…”