Particle-Induced X-ray Emission (PIXE) of silicate coatings on high impact resistance polycarbonates

Particle-Induced X-ray Emission (PIXE) analysis was employed to characterize hydroxypropyl methylcellulose (HPMC) C₃₂ H₆₀ O₁₉ polymer film via areal density measurement on silicon-based substrates utilizing the differential PIXE concept, and compared with Rutherford backscattering spectrometry (RBS) results. It is demonstrated in this paper that PIXE and RBS measurements both yield comparable results for areal densities ranging from 10¹⁸ atom/cm² to several 10¹⁹ atom/cm². A collection of techniques including PIXE, RBS, tapping mode atomic force microscopy (TMAFM), and contact angle analysis were used to compute surface free energy, analyze surface topography and roughness parameters, determine surface composition and areal density, and to predict the water affinity and condensation behaviors of silicates and other compounds used for high impact resistance vision ware coatings. The visor surface under study is slightly hydrophilic, with root mean square of surface roughness on the order of one nm, and surface wavelength between 200 nm and 300 nm. Water condensation can be controlled on such surfaces via polymers adsorption. HPMC polymer areal density measurement supports the analysis of the surface water affinity and topography and the subsequent control of condensation behavior. HPMC film between 10¹⁸ atom/cm² and 10¹⁹ atom/cm ² was found to effectively alter the water condensation pattern and prevents fogging by forming a wetting layer during condensation.